Anesthesia Protocols for Surgery during Neuromonitoring Anesthesiology, University of Colorado Denver: [email protected] April 1, 2009

A variety of anesthesia methods can be used during surgery where intraoperative neurophysiological monitoring is used. Clearly the anesthesia must be titrated to each patient to adjust for the various comorbidities, including the degree of neural compromise that may impact monitoring, as well as searching to find an anesthetic that allows an adequate monitoring signal while keeping the patient adequately anesthetized. In general, with respect to monitoring, the choice of anesthesia depends on the particular monitoring modalities being used. The major limitations are when techniques are sensitive to inhalational agents (IH) and when they are sensitive to neuromuscular blocking agents (NMB). Some modalities are insensitive to both (e.g. ABR), others are sensitive to muscle relaxants only (e.g. EMG), or inhalational agents only (e.g. cortical SSEP), and some are sensitive to both inhalational agents and muscle relaxants (e.g. transcranial motor evoked potentials (MEP)). The most restrictive techniques among the techniques used for a specific surgery define the overall anesthetic approach and the protocols below are the protocols which I usually start with for various types of monitoring. I have also mentioned some alternatives to the approach I use. These protocols are for adults; children may require different doses or approaches.

Monitoring During Posterior Fossa Surgery

When surgery in the posterior fossa involves only the Auditory Brainstem Response (ABR), there are no anesthetic considerations since this is neither sensitive to inhalational agents or muscle relaxants; any anesthetic technique is fine with respect to monitoring and should be guided to the patient and surgery. In the unlikely event that the Eustacean tube is blocked then Nitrous Oxide could cause a middle ear tension that would make its use a problem.

Anesthesia for ABR (techniques insensitive to IH or NMB) Induction as usual Maintenance as usual (IH and NMB as desired)

The most common addition to ABR is monitoring using EMG of various cranial nerves, especially the facial nerve. As such the monitoring then becomes sensitive to muscle relaxants. For some EMG techniques where the nervous system is stimulated (e.g. MEP, Pedicle screws), partial muscle relaxation is often acceptable (see below), but when monitoring is designed to be sensitive to mechanical stimulation of the nerves (as is usually the case with cranial nerves) muscle relaxants reduce the EMG amplitude and make the monitoring less sensitive to impending neural injury. For this reason I try to avoid muscle relaxation during the case. In surgeries where ABR is combined with EMG, since there is no inhalational agent restriction, I usually use a balanced anesthetic (e.g. some opioids and inhalational agents) and allow the muscle relaxants that were used with intubation to wear off. Since higher doses of inhalational agents can be used, this anesthetic works fine. The situation gets a bit more complex when the SSEP is used as in cortical surgery.

Anesthesia for ABR with EMG (insensitive to IH sensitive to NMB) Induction as usual Maintenance as usual (IH as desired) Let NMB wear off after induction

Monitoring the Cerebral Cortex

A variety of procedures involve monitoring for potential neural compromise to the cerebral cortex. A good example is Carotid Endarterectomy. If the only monitoring modality is EEG, the anesthesia is made rather easy since it is insensitive to muscle relaxants and only sensitive to high doses of inhalational agents. Hence the choice of anesthesia is usually designed to produce a rhythmic EEG in the alpha range (8‐12 Hz) that is associated with light to moderate anesthesia with inhalational agents. Higher doses will produce burst suppression or electrical silence which impairs monitoring so inhalational doses in the 1 MAC or lower range is usually fine and can be titrated to the EEG. This usually produces excellent anesthesia provided that additional opioids are used to supplement the analgesia (with the inhalational agents producing amnesia and sedation). A processed EEG monitor may be used to help insure adequate sedation in most patients if the IH dose is low (less than ½ MAC). The opioids have the additional advantage of slowing the heart rate and blunting hypertensive episodes which are important in reducing the cardiac risk in these patients. This technique also allows maintenance of the blood pressure in the patient’s usual range and is excellent for TCD monitoring. For this reason I usually load these patients with 1 ug/kg or more of fentanyl (or a similar dose of another opioid) with induction and run a balanced anesthetic with inhalational agents.

Anesthesia for EEG (moderately sensitive to IH insensitive to NMB) Induction as usual Balanced Maintenance (6% Des ~ 1 MAC) Opioids and NMB as needed

Anesthesia comes a bit more difficult if SSEP is used with the EEG for cortical monitoring as would be done in intracranial aneurysm surgery. Here the inhalational agent must be kept low enough to keep the cortical SSEP responses monitorable. In general, cortical SSEP amplitudes will be acceptable with inhalational agent concentrations between ½ and 1 MAC, however the effect is non‐linear; there is usually a concentration “threshold” in that range above which the cortical SSEP response is markedly reduced in amplitude. The problem is that each patient may have a different threshold so the inhalational agent must be titrated to effect. My approach is to plan a balanced anesthetic with some opioid, muscle relaxants as needed, and adjust the inhalational agent, observing the response. I use Desflurane or Sevoflurane when possible because their insolubility allows rapid increase and decrease of effect. For young, healthy patients with minimal neurological debility I usually start at 1 MAC and titrate down, and for older and neurologically compromised patients I start at ½ MAC and titrate up. Recall that inhalational doses in excess of 1 MAC may produce brain swelling from increased cerebrovascular arterial volume (as well as amplitude depression of the SSEP) so I don’t go above 1 MAC with intracranial cases. If the dose of inhalational agents must be kept low to allow monitoring, I often will add a propofol infusion to insure adequate sedation and opioids as needed. A processed EEG monitor is often helpful with this, provided the electrode contacts with the brain are not altered by the craniotomy and the brain does not move away from the frontal bone. For intracranial surgery this additional infusion of propofol to prevent awareness and sedation is often not necessary (it something about operating on the brain), but there is a high possibility of this in spinal surgery where SSEP is used since awareness appears to be more common.

Anesthesia for Cortical Surgery with SSEP (sensitive to IH insensitive to NMB) Induction as usual, preferably Propofol Balanced Maintenance (3‐6% Des ½‐1 MAC) Opioids and NMB as needed Propofol infusion if needed by EEG

Monitoring during Spinal Surgery using the SSEP

When I am providing anesthesia for spinal surgery where only the SSEP is used (such as spinal corrective surgery below L2), I approach the choice as above – a balanced anesthetic using opioids and muscle relaxation as needed and ½ to 1 MAC inhalational agent (Des) as acceptable to acquire a cortical response (titrating as described above). As opposed to intracranial surgery, I find I usually need a supplemental infusion of propofol and usually use an infusion of opioid. The propofol usually runs at 60‐ 120 ug/kg/min (often titrated with the help of a processed EEG). For the opioid I usually use sufentanil (unless it’s an elderly frail patient where I bolus fentanyl to effect). Sufentanil infusions usually run 0.15‐0.3 ug/kg/hr, but can be higher depending on the patient’s tolerance from preoperative analgesic use. Note the sufentanil infusion needs to be turned off about 30 minutes before ending. Note that fentanyl (infusion 4‐5 ug/kg/hr) can be used as can remifentanil (0.2‐0.5 ug/kg/min). Fortunately the inhalational agents help a lot with the anesthetic.

Anesthesia for Spinal Surgery with SSEP (sensitive to IH insensitive to NMB) Induction as usual (preferable Propofol) Balanced Maintenance (3‐6% Des ½‐1 MAC) Opioids – sufentanil bolus as needed than 0.15‐0.3 ug/kg/hr turn off 30 minutes before end Propofol infusion guided by EEG (60‐120 ug/kg/min) NMB as needed if EMG not monitored

An alternative approach here is to use dexmeditomidine instead of, or supplementary to the propofol. Some individuals use Dex infusions of 0.2‐0.5 ug/kg/hr. I usually don’t load the Dex (which cuts the cost) if it’s started at the beginning of the case. The infusion of Propofol will be a lower dose due to the sedation from the Dex. Because the mechanism of action is not opioid like (it’s a central alpha2 stimulant), it appears to be helpful in opioid tolerant patients.

Alternate anesthesia for Spinal Surgery with SSEP (sensitive to IH insensitive to NMB) Induction as usual (preferable Propofol) Balanced Maintenance (3‐6% Des ½‐1 MAC) Opioids – sufentanil bolus as needed than 0.15‐0.3 ug/kg/hr turn off 30 minutes before end Dexmeditomidine (0.2‐0.5 ug/kg/hr) Propofol infusion (60‐100 ug/kg/min) NMB as needed if no EMG

If EMG is also monitored with the SSEP (which is usually the case with our surgeries), the muscle relaxants must be restricted. I prefer to let the muscle relaxants wear off after the beginning of surgery. After the baseline recordings are done, sometimes we will use some relaxation for the opening of a large spinal surgery to reduce the muscle activity or assist in the exposure of an anterior abdominal case. Although I prefer to use no relaxation during the monitoring portion of the procedure, acceptable EMG monitoring can be done with 2 twitches in a train of four, optimally using a titrated infusion of an intermediate acting drug such as rocuronium (5‐10 ug/kg/min) or vecuronium (0.5‐0.8 ug/kg/min). Data suggests that a deeper block (only 1 twitch), may artificially increase the pedicle screw threshold which could reduce the ability to signal the need for repositioning of the screws. In addition, the detection of nerve root compromise from mechanical means might be reduced similar to facial nerve monitoring above, such that no relaxation is desirable. In general, since the sensitivity of muscle groups to muscle relaxants varies, where the TOF is monitored is important. Since distal muscles are most sensitive (and frequently where monitoring is done), if we monitor the TOF using the ulnar nerve and hand response is probably best since more proximal muscles (such as on the face) may underestimate the effect in the periphery. The best neuromuscular monitoring of TOF will be done by the monitoring team in the muscles they are monitoring (note they need to use the same technique as anesthesia with a TOF at 2 Hz).

Anesthesia for Spinal Surgery with SSEP & EMG (sensitive to IH & NMB) Induction as usual (preferable Propofol) Balanced Maintenance (3‐6% Des ½‐1 MAC) Opioids – sufentanil bolus as needed than 0.15‐0.3 ug/kg/hr turn off 30 minutes before end Propofol infusion guided by EEG (50‐150 ug/kg/min) NMB as needed for induction, possibly for muscle dissection then none (acceptable 2+/4 twitches in TOF in muscles monitored for monitoring nerve stimulation)

Monitoring the SSEP when a Reduction or Elimination of the Inhalational Agents is Needed

In general, the ability to use inhalational agents and partial muscle relaxation is very helpful in anesthetizing the spine surgery patients (particularly if they are opioid tolerant). The situation becomes much more difficult when the responses are so poor that the inhalational agent must be reduced or eliminated. In this case the anesthesia becomes a total intravenous anesthetic (TIVA) with the sedation being provided by propofol (75‐150 ug/kg/min, usually titrated to processed EEG) with an opioid infusion (e.g. sufentanil 0.3‐0.5 ug/kg/hr). If the SSEP remains too small for monitoring, an infusion of etomidate (0.6 mg/kg/hr) can be used instead of the propofol (as etomidate enhances the cortical SSEP at low doses). Alternatively a ketamine infusion (1‐2 mg/kg/hr) can be used with the opioid infusion (see below for our approach to ketamine) since ketamine also increases the cortical SSEP response. Since our spine surgeries most often use transcranial motor evoked responses when we need to eliminate the inhalational agents, we take the TIVA approach described below when low dose of inhalational agents are not acceptable for MEP.

Monitoring when Motor evoked Potentials are used

The most challenging anesthetic is required during monitoring of surgery when motor evoked potentials are being used because both the inhalational agents and neuromuscular blocking agents must be severely restricted or not used. With these cases SSEP and EMG are also usually being monitored, but the MEP defines the major restrictions. For a medically healthy patient who is without marked neurological problems (i.e. usually presents with severe pain that prompts surgery), I usually start with a TIVA technique supplemented with ½ MAC of inhalational agent (e.g. 3% Des). Some folks start with pure TIVA, but frequently a small amount of Des or Sevo is acceptable and I believe it is helpful, especially with patients who are opioid tolerant. Hence, after a standard induction with propofol and a short or intermediate acting muscle relaxant (which I let wear off), I will use 3% Des, a sufentanil infusion (0.3‐0.5 ug/kg/hr) and a propofol infusion (75‐150 ug/kg/min titrated to processed EEG). Note that some individuals would prefer to use 50‐60% nitrous oxide instead of the Des (but not both IH and N2O together at the same time since they are synergistic and the effect is usually too much). This works similarly but I prefer to not have my FiO2 restricted by nitrous oxide and that when turning the nitrous off in a time of concern may cause an abrupt change in anesthesia and monitoring. This technique usually works well, but occasionally the MEP responses are too small which necessitates turning off the Des and adjusting the Propofol and sufentanil infusions as needed. It’s important to note that moderate doses of benzodiazepines and barbiturates have been reported to reduce the MEP response and that this may last a long time (much longer than the drug duration of action). It is not clear how this pertains to the modern multipulse technique; however, small doses of midazolam appear quite acceptable such as those that are customarily used for preinduction or occasionally during the case.

Anesthesia for Spinal Surgery with MEP & EMG (very sensitive to IH & NMB) Induction as usual (preferable Propofol) Low dose IH (3% Des) Opioids – sufentanil bolus as needed than 0.15‐0.3 ug/kg/hr turn off 30 minutes before end Propofol infusion guided by EEG (75‐150 ug/kg/min) NMB as needed for induction, possibly for muscle dissection then none (acceptable 2+/4 twitches in TOF in muscles monitored for monitoring nerve stimulation)

Monitoring MEP with Opioid Tolerant Patients or Who have Significant Neurological Disability

In patients who are not young and healthy or have moderate neural disability or where turning off the Des is required in the above technique, I usually use pure TIVA using propofol and sufentanil.

Anesthesia for Spinal Surgery with MEP & EMG (very sensitive to IH & NMB) Induction as usual (preferable Propofol) Pure TIVA – no IH Opioids – sufentanil bolus as needed than 0.15‐0.3 ug/kg/hr turn off 30 minutes before end Propofol infusion guided by EEG (75‐175 ug/kg/min) NMB as needed for induction, possibly for muscle dissection then none (acceptable 2+/4 twitches in TOF in muscles monitored for monitoring nerve stimulation)

If this isn’t sufficient to allow monitoring, or in patients who are very opioid tolerant or who have significant neurological debility where the responses are likely to be poor I use TIVA enhanced with ketamine. In this case I use ketamine to supplement the analgesia (recall it has NMDA action that the opioids do not). It also supplements the sedation which allows a reduction in the propofol infusion rate (and a reduction in the depressant effect of the propofol). The notable thing about ketamine is that it is metabolized slower than propofol so that the infusion must be turned down earlier than the propofol. One approach is to run a separate infusion of ketamine (1‐2 mg/kg/hr), but since we currently titrate the sedation to the processed EEG, it’s more convenient to mix the ketamine with the propofol. As such, we mix ketamine in the propofol for an initial infusion that has 2 mg of ketamine in each cc of propofol (e.g. 100 mg ketamine in a 50 cc syringe of propofol). This infusion is titrated to the EEG (since ketamine can increase the numeric value of the processed EEG, I titrate to the high end of the acceptable processed EEG range). This concentration of ketamine is reduced with each subsequent 50 cc syringe of propofol. For a shorter case I usually go 2, then 1.5, then 1, then 0.5 mg of ketamine per cc and use no ketamine in the final syringes. For a much longer case I taper more slowly. Note that the ketamine will increase the SSEP amplitude so you may see a slow decline in SSEP amplitude over the case (often to 50%) and this is expected and must be differentiated from a pathologic change.

Anesthesia for Spinal Surgery with MEP & EMG (very sensitive to IH & NMB) Induction as usual (preferable Propofol) Pure TIVA – no IH Opioids – sufentanil bolus as needed than 0.3‐0.5 ug/kg/hr turn off 30 minutes before end Propofol infusion guided by EEG (75‐175 ug/kg/min) Ketamine mixed in the Propofol (initial 2 mg/cc) and tapered to off NMB as needed for induction, possibly for muscle dissection then none (acceptable 2+/4 twitches in TOF in muscles monitored for monitoring nerve stimulation)

The major alternative to this is to use dexmeditomidine as described above. Hence some individuals use <0.5 ug/kg/hr Dexmeditomidine instead of the propofol (or with a small dose of Propofol 50‐60 ug/kg/min). However, I must note that many individuals report that MEP are difficult to obtain with Dex. As such the use of Dex is evolving.

Anesthesia for Spinal Surgery with MEP & EMG (very sensitive to IH & NMB) Induction as usual (preferable Propofol) Pure TIVA – no IH Opioids – sufentanil bolus as needed than 0.3‐0.5 ug/kg/hr turn off 30 minutes before end Propofol infusion guided by EEG (60‐100 ug/kg/min) Dexmeditomidine (0.3‐0.5 ug/kg/hr) NMB as needed for induction, possibly for muscle dissection then none (acceptable 2+/4 twitches in TOF in muscles monitored for monitoring nerve stimulation)

Dexmeditomidine would also be an acceptable alternative in patients where propofol is contraindicated (such as allergy to soy or eggs or a history of propofol infusion syndrome). Similarly, etomidate could be used. Low dose IH or nitrous oxide might also be acceptable as long as the depressant effect was not excessive. It is also worth mentioning that in patients where an intravenous line is not available for induction a mask induction with sevoflurane with or without nitrous oxide works fine. Usually these can be eliminated after transition to intravenous techniques in time for the need for intraoperative monitoring.

Conclusion

In general, I pick the initial anesthetic technique based on the patient comorbidities (choice of anesthesia drugs independent to monitoring), patient tolerance to analgesics used preoperatively, the degree of patient neural disabilities, the actual surgery to be performed, and the specific monitoring modalities to be used. As such the doses above are only approximate and should be verified as appropriate and adjusted for each individual patient. My goal is to get the maintenance anesthetic on board and see how the monitoring responses are doing, making required changes in the technique as rapidly as possible so that I can have a steady state anesthetic effect during the period of the surgery when monitoring needs to focus on changes that might be the result of surgical or physiological changes (hence infusions are extremely valuable). I uniformly use the processed EEG to titrate/insure sedation (BIS, Sedline, SNAP, etc.), relying on blood pressure and heart rate to guide adequate analgesia. Although I recognize that these devices will not always insure adequate sedation or anmesia, especially when ketamine is present since it increases the processed indices. However, if recall was to occur, I can say in good faith that I did what might be helpful. I most often use sufentanil with bolus doses around induction and then by infusion. Fentanyl and remifentanil work fine when used in a similar fashion. I favor Desflurane because its insolubility allows rapid changes, however Isoflurane, Sevoflurane and Nitrous Oxide will also work. If a mask induction is used then Sevoflurane is preferable. I also prefer propofol for induction so that the patient is loaded for an infusion (ketamine and dexmeditomidine are described as needing loading doses, but do not appear to need them when used as above). Obviously substitutions may be necessary for individual drug sensitivities and some individuals express concern with propofol in children (propofol infusion syndrome). I also favor no muscle relaxation when the technique is sensitive (especially spontaneous EMG). I recognize that there is ample literature showing partial relaxation is acceptable, however, I am concerned about regulating the degree of relaxation leading to an iatrogenic loss of response. Usually these protocols work quite well, although I occasionally have a patient a couple times a year who I just can’t keep down. My approach is usually to add inhalational agents so that we maintain the SSEP and EMG monitoring, sacrificing the MEP rather than using NMB and losing the EMG and MEP.

“Clinical topic reviews” are an effort to update and inform the practice. In general, the topics pertain to the overall practice of anesthesiology. On occasion, they specifically address departmental education surrounding new or current clinical circumstances in our workplace at Saint John’s. They may serve as a means of demonstrating compliance with regulatory standards or practice awareness of current standards and guidelines. It may also serve as evidence for participation in FFPE (focused professional practice evaluation). FFPE is a requirement for MOCA (Maintenance of Certification in Anesthesiology).

An individual’s participation is voluntary. Your input is valued and encouraged. If you identify, in your element of the practice, a clinical topic that you think warrants increased departmental awareness then you are encouraged to submit ideas for a “clinical topic review.” Forward your ideas to the current VP of Clinical Affairs on the Board of Directors of Western Anesthesiology. Please provide explicit information (eg. Video link, journal article, medical or regulatory website). Chosen topics will be distributed via email. Your attestation that you have participated will be documented with the use of “Survey Monkey.” The frequency of distributions of clinical topics will occur regularly or according to necessity.

THIS SESSION'S CLINICAL TOPIC REVIEW IS: "SAFE INJECTION PRACTICES FROM THE JOINT COMMISSION". To view the video, click or paste the below link into your web browser. NEXT, press the arrow in the black screen.

http://www.oneandonlycampaign.org/videos/Default.aspx

After you are done watching the video, click the survey link and give us your input on this months topic. https://www.surveymonkey.com/s.aspx?sm=bPkVYe52YyvKg9oRyNj8qWwpeuhh9vP6R_2fcCTwMG 0Lw_3d

Thank you.

Respectfully,

Andrew M. Barnett, MD

SPECIAL ARTICLES

Anesthesiology 2009; 110:459–79 Copyright © 2009, the American Society of Anesthesiologists, Inc. Lippincott Williams & Wilkins, Inc. Practice Advisory on Anesthetic Care for Magnetic Resonance Imaging A Report by the American Society of Anesthesiologists Task Force on Anesthetic Care for Magnetic Resonance Imaging*

PRACTICE advisories are systematically developed re- netic field. Secondary dangers of these energy sources ports that are intended to assist decision making in include high-level acoustic noise, systemic and localized areas of patient care. Advisories are based on a syn- heating, and accidental projectiles. There may be signif- thesis of scientific literature and analysis of expert and icant challenges to anesthetic administration and moni- practitioner opinion, clinical feasibility data, open fo- toring capabilities due to static and dynamic magnetic rum commentary, and consensus surveys. Advisories fields as well as radiofrequency energy emissions. Direct developed by the American Society of Anesthesiolo- patient observation may be compromised by noise, dark- gists (ASA) are not intended as standards, guidelines, ened environment, obstructed line of sight, and other or absolute requirements. They may be adopted, mod- characteristics unique to this environment (e.g., distrac- ified, or rejected according to clinical needs and con- tions). Unlike a conventional operating room, the MRI straints. environment frequently requires the anesthesiologist to The use of practice advisories cannot guarantee any assume broader responsibility for immediate patient care specific outcome. Practice advisories summarize the decisions. state of the literature, and report opinions obtained from expert consultants and ASA members. Practice adviso- Methodology ries are not supported by scientific literature to the same degree as standards or guidelines because of the lack of A. Definition of Anesthetic Care for MRI and High- sufficient numbers of adequately controlled studies. risk Imaging Practice advisories are subject to periodic revision as This Advisory defines anesthetic care for MRI as mod- warranted by the evolution of medical knowledge, tech- erate sedation, deep sedation, monitored anesthesia nology, and practice. care, general anesthesia, or ventilatory and critical care The magnetic resonance imaging (MRI) suite is a haz- support. High-risk imaging refers to imaging in patients ardous location because of the presence of a strong with medical or health-related risks; imaging with equip- static magnetic field, high-frequency electromagnetic ment-related risks; and procedure-related risks, such as (radiofrequency) waves, and a time-varied (pulsed) mag- MRI-guided surgery, minimally invasive procedures (e.g., focused ultrasound, radiofrequency ablation), or cardiac and airway imaging studies. Supplemental digital content is available for this article. Direct  URL citations appear in the printed text and are available in both the HTML and PDF versions of this article. Links to the B. Purpose digital files are provided in the HTML text of this article on the The purposes of this Advisory are to (1) promote Journal’s Web site (www.anesthesiology.org). patient and staff safety in the MRI environment, (2) prevent the occurrence of MRI-associated accidents, (3) promote optimal patient management and reduce ad- * Developed by the American Society of Anesthesiologists Task Force on Anes- verse patient outcomes associated with MRI, (4) identify thetic Care for Magnetic Resonance Imaging: Jan Ehrenwerth, M.D. (Co-chair), Madison, Connecticut; Mark A. Singleton, M.D., San Jose, California (Co-chair); potential equipment-related hazards in the MRI environ- Charlotte Bell, M.D., Milford, Connecticut, Jeffrey A. Brown, D.O., Cleveland, Ohio; ment, (5) identify limitations of physiologic monitoring Randall M. Clark, M.D., Denver, Colorado; Richard T. Connis, Ph.D., Woodinville, Washington; Robert Herfkens, M.D., Stanford, California; Lawrence Litt, M.D., Ph.D., capabilities in the MRI environment, and (6) identify San Francisco, California; Keira P. Mason, M.D., Wellesley Hills, Massachusetts; Craig potential health hazards (e.g., high decibel levels) of the D. McClain, M.D., Brookline, Massachusetts; David G. Nickinovich, Ph.D., Bellevue, Washington; Susan M. Ryan, M.D., Ph.D., San Francisco, California; and Warren S. MRI environment. Sandberg, M.D., Ph.D., Boston, Massachusetts. Submitted for publication October 24, 2008. Accepted for publication Octo- C. Focus ber 24, 2008. Supported by the American Society of Anesthesiologists under the direction of James F. Arens, M.D., Chair, Committee on Standards and Practice This Advisory focuses on MRI settings where anes- Parameters. Approved by the House of Delegates on October 22, 2008. A thetic care is provided, specifically facilities that are complete list of references used to develop this Advisory is available by writing to the American Society of Anesthesiologists. designated as level II or III (appendix 1). Level II Address reprint requests to the American Society of Anesthesiologists: 520 refers to facilities that image patients requiring moni- North Northwest Highway, Park Ridge, Illinois 60068-2573. This Practice Advi- sory, as well as all published ASA Practice Parameters, may be obtained at no cost toring or life support. Level III refers to facilities that through the Journal Web site, www.anesthesiology.org. are designed for operative procedures. This Advisory

Anesthesiology, V 110, No 3, Mar 2009 459 460 PRACTICE ADVISORY

Table 1. Zone Definitions1

Zone I This region includes all areas that are freely accessible to the general public. This area is typically outside the MR environment itself and is the area through which patients, healthcare personnel, and other employees of the MR site access the MR environment. Zone II This area is the interface between the publicly accessible uncontrolled zone I and the strictly controlled zone III (see below). Typically, the patients are greeted in zone II and are not free to move throughout zone II at will, but rather are under the supervision of MR personnel. It is in zone II that patient histories, answers to medical insurance questions, and answers to magnetic resonance imaging screening questions are typically obtained. Zone III This area is the region in which free access by unscreened non-MR personnel or ferromagnetic objects or equipment can result in serious injury or death as a result of interactions between the individuals or equipment and the MR scanner’s particular environment. These interactions include, but are not limited to, those with the MR scanner’s static and time- varying magnetic fields. All access to zone III is to be strictly restricted, with access to regions within it (including zone IV; see below) controlled by, and entirely under the supervision of, MR personnel. Zone IV This area is the MR scanner magnet room. Zone IV, by definition, will always be located within zone III because it is the MR magnet and its associated magnetic field, which generates the existence of zone III.

MR ϭ magnetic resonance. does not apply to level I facilities, where no anesthetic ing methodologists from the ASA Committee on Stan- care is provided. dards and Practice Parameters. Four zones within the MRI suite have been identified, The Task Force developed the Advisory by means of with ascending designations indicating increased hazard a seven-step process. First, they reached consensus on areas.1,2 These areas within the MRI suite are categorized the criteria for evidence. Second, a systematic review as zones I–IV (table 1). and evaluation was performed on original published research studies from peer-reviewed journals relevant D. Application to MRI safety. Third, a panel of expert consultants was This Advisory is intended for use by anesthesiolo- asked to (1) participate in opinion surveys on the gists or other individuals working under the supervi- effectiveness of various MRI safety strategies and (2) sion of an anesthesiologist, and applies to anesthetic review and comment on a draft of the Advisory devel- care performed, supervised, or medically directed by oped by the Task Force. Fourth, opinions about the anesthesiologists, or to moderate sedation care super- Advisory were solicited from a random sample of vised by other physicians. Because the safe conduct of active members of the ASA. Fifth, the Task Force held MRI procedures requires close collaboration and an open forum at two major national meetings† to prompt coordination between anesthesiologists, radi- solicit input on its draft recommendations. Sixth, the ologists, MRI technologists, and nurses, some respon- consultants were surveyed to assess their opinions on sibilities are shared among the disciplines. When the feasibility of implementing this Advisory. Seventh, shared responsibilities are described in this Advisory, all available information was used to build consensus the intent is to give the anesthesiologist a starting within the Task Force to create the final document, as point for participating in the allocation and under- summarized in appendix 2. standing of shared responsibilities. The Advisory may also serve as a resource for other physicians and healthcare professionals (e.g., technologists, nurses, F. Availability and Strength of Evidence safety officers, hospital administrators, biomedical en- Preparation of this Advisory followed a rigorous meth- gineers, and industry representatives). odologic process (appendix 3). Evidence was obtained This Advisory does not address specific anesthetic from two principal sources: scientific evidence and opin- drug choices and does not apply to patients who receive ion-based evidence. minimal sedation (anxiolysis) to complete the scan or Scientific Evidence. Study findings from published procedure safely and comfortably. scientific literature were aggregated and are reported in summary form by evidence category, as described below. All literature (e.g., randomized controlled tri- E. Task Force Members and Consultants als, observational studies, case reports) relevant to The ASA appointed a Task Force of 13 members. each topic was considered when evaluating the find- These individuals included 10 anesthesiologists in pri- ings. For reporting purposes in this document, the vate and academic practice from various geographic highest level of evidence (i.e., level 1, 2, or 3 identified areas of the United States, 1 radiologist, and 2 consult- below) within each category (i.e., A, B, or C) is indi- cated in the summary. † 82nd Clinical and Scientific Congress of the International Anesthesia Re- Category A: Supportive Literature. Randomized con- search Society, San Francisco, California, March 30, 2008, and Annual Meeting of the Society for Pediatric Anesthesia, San Diego, California, April 5, 2008. trolled trials report statistically significant (P Ͻ 0.01)

Anesthesiology, V 110, No 3, Mar 2009 PRACTICE ADVISORY 461 differences among clinical interventions for a specified Opinion-based Evidence. All opinion-based evi- clinical outcome. dence relevant to each topic (e.g., survey data, open- Level 1: The literature contains multiple randomized forum testimony, Internet-based comments, letters, edi- controlled trials, and the aggregated findings are sup- torials) is considered in the development of this ported by meta-analysis.‡ Advisory. However, only the findings obtained from for- Level 2: The literature contains multiple randomized mal surveys are reported. controlled trials, but there is an insufficient number of Opinion surveys were developed by the Task Force to studies to conduct a viable meta-analysis for the purpose address each clinical intervention identified in the doc- of this Advisory. ument. Identical surveys were distributed to two groups Level 3: The literature contains a single randomized of respondents: expert consultants and ASA members. controlled trial. Category A: Expert Opinion. Survey responses from Category B: Suggestive Literature. Information from Task Force–appointed expert consultants are reported observational studies permits inference of beneficial or in summary form in the text. A complete listing of harmful relations among clinical interventions and clini- consultant survey responses is reported in table 2 in cal outcomes. appendix 3. Level 1: The literature contains observational compar- Category B: Membership Opinion. Survey responses isons (e.g., cohort, case–control research designs) of two from a random sample of members of the ASA are re- or more clinical interventions or conditions and indi- ported in summary form in the text. A complete listing of cates statistically significant differences between clinical ASA member survey responses is reported in table 3 in interventions for a specified clinical outcome. appendix 3. Level 2: The literature contains noncomparative obser- Survey responses are recorded using a 5-point scale vational studies with associative (e.g., relative risk, cor- and summarized based on median values.§ relation) or descriptive statistics. Level 3: The literature contains case reports. Strongly agree: median score of 5 (at least 50% of the Category C: Equivocal Literature. The literature can- responses are 5) not determine whether there are beneficial or harmful Agree: median score of 4 (at least 50% of the responses are relations among clinical interventions and clinical out- 4 or 4 and 5) comes. Equivocal: median score of 3 (at least 50% of the responses Level 1: Meta-analysis did not find significant differ- are 3, or no other response category or combination of ences among groups or conditions. similar categories contain at least 50% of the responses) Level 2: There is an insufficient number of studies to Disagree: median score of 2 (at least 50% of the responses conduct meta-analysis and (1) randomized controlled are 2 or 1 and 2) trials have not found significant differences among Strongly disagree: median score of 1 (at least 50% of groups or conditions or (2) randomized controlled trials the responses are 1) report inconsistent findings. Category C: Informal Opinion. Open-forum testi- Level 3: Observational studies report inconsistent find- mony, Internet-based comments, letters, and editorials ings or do not permit inference of beneficial or harmful are all informally evaluated and discussed during the relations. development of the Advisory. When warranted, the Task Category D: Insufficient Evidence from Literature. Force may add educational information or cautionary The lack of scientific evidence in the literature is de- notes based on this information. scribed by the following terms. Silent: No identified studies address the specified rela- tions among interventions and outcomes. Advisories Inadequate: The available literature cannot be used to assess relations among clinical interventions and clinical I. Education outcomes. The literature either does not meet the crite- MRI safety education includes, but is not limited to, ria for content as defined in the “Focus” of the Advisory topics addressing: (1) MRI magnet hazards in zones III and or does not permit a clear interpretation of findings IV, (2) challenges and limitations of monitoring, and (3) long- because of methodologic concerns (e.g., confounding in term health hazards. study design or implementation). There is insufficient published evidence to evaluate the effect of education regarding magnet hazards, mon- itoring limitations, or long-term health hazards associ- ‡ All meta-analyses are conducted by the ASA methodology group. Meta- analyses from other sources are reviewed but not included as evidence in this ated with MRI. [Category D evidence] One observational document. study examined the potential long-term health hazards of § When an equal number of categorically distinct responses is obtained, the median value is determined by calculating the arithmetic mean of the two middle pregnant MRI workers and pregnant non-MRI workers, values. Ties are calculated by a predetermined formula. and found no significant difference in the relative risk of

Anesthesiology, V 110, No 3, Mar 2009 462 PRACTICE ADVISORY early delivery, low birth weight, or spontaneous abor- Advisory Statements. The anesthesiologist should tions.3 [Category C evidence] work in collaboration with the MRI medical director or The consultants and ASA members strongly agree that designee (e.g., safety officer) to ensure that all anesthesia all anesthesiologists should have general safety educa- team personnel entering zone III or IV have been tion on the unique physical environment of the MRI screened for the presence of ferromagnetic materials, scanner. The ASA members agree and the consultants foreign bodies, or implanted devices. strongly agree that all anesthesiologists should have spe- cific education regarding the features of individual scan- III. Patient Screening ners within their institution. The ASA members agree Patient screening consists of determining patient and and the consultants strongly agree that anesthesiologists equipment-related risks for adverse outcomes associated should work in collaboration with radiologists, technol- with MRI procedures. ogists, and physicists within their institutions to develop Patient-related Risks: Risks related to the patient may safety training programs. include age-related risks, health-related risks, and risks Advisory Statements. All anesthesiologists should from foreign bodies located in or on the patient or have general safety education on the unique physical implanted ferromagnetic items. Age-related risks apply environment of the MRI scanner and specific education to neonates or premature infants, and elderly patients. regarding the specific features of individual scanners Health-related risks include, but are not limited to, (1) within their institution. Education should emphasize the need for intensive or critical care; (2) impaired re- safety for entering zones III and IV, with special empha- spiratory function (e.g., tonsillar hypertrophy, sleep ap- sis on hazards in this environment and effects on moni- nea); (3) changes in level of sedation, muscle relaxation, toring capabilities. Education should address potential or ventilation; (4) hemodynamic instability and vasoac- health hazards (e.g., high decibel levels and high-inten- tive infusion requirements; and (5) comorbidities that sity magnetic fields) and necessary precautions to deal may contribute to adverse MRI effects (e.g., burns or with the specific field strength and the safety of the MRI temperature increases in patients with obesity or periph- scanners within their institutions. Education should in- eral vascular disease). Risks from foreign bodies include clude information regarding ferromagnetic items (e.g., nonmedical ferromagnetic items imbedded in the pa- stethoscopes, pens, wallets, watches, hair clips, name tient (e.g., eyeliner tattoos, metallic intraocular frag- tags, pagers, cell phones, credit cards, batteries) and ments) or attached to the patient (e.g., pierced jewelry, implantable devices (e.g., spinal cord stimulators, im- magnetic dental keepers). Risk from implanted ferro- planted objects) that should not be brought into zone magnetic items may include such items as aneurysm III or IV of the MRI suite or should be brought in with clips, prosthetic heart valves, or coronary arterial stents. caution. Anesthesiologists should work in collabora- One comparative study reports that neonates undergoing tion with radiologists, technologists, and physicists MRI demonstrate increased fluctuations in heart rate, blood within their institutions to ensure that the above top- pressure, and oxygen saturation levels compared with ne- ics are included in their safety training programs. onates not undergoing MRI.4 [Category B1 evidence] Two Finally, education should include how to safely re- observational studies report that premature neonates can spond to code blue situations in zones III and IV, and experience heart rate fluctuations, decreases in oxygen this information should be integrated into protocols saturation, and increases in temperature during MRI.5,6 for the designated code blue team. [Category B2 evidence] One case report indicates that a child with a history of previous cardiac arrest experienced II. Screening of Anesthetic Care Providers and a cardiac arrest during MRI.7 [Category B3 evidence] Four Ancillary Support Personnel observational studies8–11 and two case reports12,13 indicate The MRI medical director or designated technologist is that patients with impaired renal function are at risk of responsible for access to zones III and IV. Screening of nephrogenic systemic fibrosis after gadolinium adminis- all individuals entering zone III is necessary to prevent tered for MRI. [Category B2 evidence] accidental incursions of ferromagnetic materials or inad- Case reports indicate that exposure of iron filings to the vertent exposure of personnel with foreign bodies or magnetic field may result in hemorrhage,7,14 and exposure implanted ferromagnetic items. of eyeliner tattoos may result in image artifacts, burns, The literature is silent regarding whether the screening swelling, or puffiness.7,15–17 [Category B3 evidence] Nu- of anesthesia care providers and ancillary support per- merous observational studies and case reports indicate in- sonnel improves safety in the MRI suite. [Category D teractions with the magnetic field (e.g., movements, dis- evidence] The ASA members agree and the consultants placements, image artifacts) and increases in temperature strongly agree that the anesthesiologist should work in during MRI for ferromagnetic items such as aneurysm clips, collaboration with the MRI medical director or designee surgical clips, prosthetic heart valves, intravenous infusion to ensure that all anesthesia team personnel entering pumps, coronary arterial stents, and implanted dental mag- zone III or IV have been properly screened. net keepers.18–43 [Category B2 evidence]

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Both the consultants and the ASA members strongly Both the consultants and the ASA members agree that, agree that, for every case, the anesthesiologist should for every case, the anesthesiologist should communicate communicate with the patient and radiologist or refer- with the radiologist or referring physician to determine ring physician to determine whether the patient has a whether the patient requires equipment that may pose a high-risk medical condition. In addition, they both risk during the scan. In addition, they agree that anes- strongly agree that if the patient presents with a high-risk thesiologists should determine the safety and effective- medical condition, the anesthesiologist should collabo- ness of the equipment needed by the patient during the rate with all participants, including the referring physi- procedure for each MRI location. Further, the consult- cian, radiologist, and technologist, to determine how the ants and ASA members strongly agree that anesthesiolo- patient will be managed during the MRI procedure. Both gists should work with their institutions to properly the consultants and the ASA members agree that, for identify and label anesthesia-related equipment accord- patients with acute or severe renal insufficiency, the ing to convention for each MRI scanner. The ASA mem- anesthesiologist should not administer gadolinium be- bers agree and the consultants strongly agree that care cause of the increased risk of nephrogenic systemic should be taken to ensure that anesthesia equipment fibrosis. does not interfere with image acquisition or quality. Equipment-related Risks: Patient equipment-related Both the consultants and the ASA members agree that, in risks include, but are not limited to, (1) physiologic general, MRI should not be performed on patients with monitors; (2) invasive monitors (e.g., intravascular cath- implanted electronic devices. Finally, both the consult- eters); (3) intubation equipment; (4) oxygenation and ants and the ASA members strongly agree that, when ventilation equipment; and (5) pacemakers, implanted MRI is considered essential by the referring physician cardiodefibrillators, and other implanted devices (e.g., and consulting radiologist, a plan for managing patients deep brain stimulators, vagal or phrenic nerve stimula- with implanted electronic devices during the scan tors, middle-ear or cochlear implants). should be developed in collaboration with the referring One case report notes that cardiac monitor leads inter- physician, medical director or on-site radiologist, and fered with an MRI scan.7 [Category B3 evidence] One other appropriate consultants. observational study and one case report indicate that fire Advisory Statements for Patient and Equipment- or burns occurred beneath or near cardiac monitor elec- related Risks. For every case, the anesthesiologist trodes.44,45 [Category B2 evidence] Five case reports should communicate with the patient, referring physi- note that burns occurred from the looping of a temper- cian, and radiologist to determine whether the patient ature probe or pulse oximetry cables.46–50 [Category B3 (1) presents with a high-risk medical condition (e.g., evidence] One observational study reports ferromag- neonatal status or prematurity, intensive or critical care netic components in ventilators51 [category B2 evi- status, impaired respiratory function, hemodynamic in- dence], and three case reports describe projectile ni- stability and vasoactive infusion requirements, comor- trous oxide or oxygen tanks52–54 [category B3 evidence]. bidities such as obesity and peripheral vascular disease); Additional observational studies and case reports indi- (2) requires equipment (e.g., physiologic or invasive cate interactions of pacemakers or implanted cardio- monitors; intubation, oxygenation, or ventilation equip- verter–defibrillators with MRI scanning, including, but ment); (3) has implanted devices (e.g., pacemakers, car- not limited to, pacing artifacts, reed switch closure, dioverter–defibrillators, nerve stimulators); (4) has been generator movement or displacement, alterations of pac- screened for the presence of implanted ferromagnetic ing rate, and temperature increases.7,55–84 [Category B2 items (e.g., surgical clips, prosthetic heart valves); and (5) evidence] Two observational studies report palpitations, has been screened for the presence of imbedded foreign rapid heart rate, and discomfort at the pacemaker pocket bodies (e.g., orbital iron filings, eyeliner tattoos). Finally, the after MRI.75,85 [Category B2 evidence] Finally, two cases anesthesiologist should communicate with the technolo- of cardiac arrest are reported in patients with pacemak- gist to ensure that the patient has been screened for the ers during or after an MRI scan; in one case, the patient presence of foreign bodies on the patient (e.g., pierced died.7,57 [Category B3 evidence] jewelry, rings) before entering zone III. Two observational studies report image artifacts when If a patient presents with a high-risk medical condition, MRI is performed in patients with neurostimulators, infu- the anesthesiologist should collaborate with all partici- sion pumps, or implantable spinal fusion stimulators.86,87 pants, including the referring physician, radiologist, and Six observational studies report increased temperatures in technologist, to determine how the patient will be man- patients with deep brain stimulators, neurostimulators, or aged during the MRI procedure. Anticipated changes in spinal cord stimulators,88–93 and three report displacement level of sedation, muscle relaxation, or ventilation may of leads, pulse generators, or other components of deep also place a patient in a high-risk situation. brain stimulators or middle ear prostheses during MRI For patients with acute or severe renal insufficiency, scans.94–96 [Category B2 evidence] the anesthesiologist should not administer gadolinium

Anesthesiology, V 110, No 3, Mar 2009 464 PRACTICE ADVISORY because of the increased risk of nephrogenic systemic equipment and personnel in the MRI suite during the fibrosis. procedure. Anesthesiologists should work with their institutions to The literature is insufficient to determine whether ac- properly identify and label anesthesia-related equipment tive preparation or pre-MRI planning reduces the fre- according to convention (safe, unsafe, or conditional) for quency of adverse events. [Category D evidence] One each MRI scanner.# For each MRI location, anesthesiolo- case report indicates that misinformation about the type gists should determine the safety and effectiveness of the of aneurysm clip resulted in intracerebral hemorrhage equipment needed by the patient during the procedure. In and death,31 and a second case report indicates that a addition, care should be taken to ensure that equipment lack of communication among physicians caring for a does not interfere with image acquisition or quality. pacemaker patient resulted in the death of the patient.97 The Task Force believes that cardiac pacemakers [Category B3 evidence] and implantable cardioverter–defibrillators are generally Both the consultants and the ASA members strongly contraindicated for MRI. These devices pose an extreme agree that, for every case, the anesthesiologist should hazard in this environment and may be life-threatening prepare, with support personnel, a plan for providing within the 5 gauss line. When MRI is considered essen- optimal anesthetic care within the special environment tial by the referring physician and consulting radiologist, of the MRI suite. They both strongly agree that the a plan for managing these patients during the scan anesthesiologist should communicate with the radiology should be developed in collaboration with the ordering personnel to determine the requirements of the scan. The physician, medical director or on-site radiologist, and ASA members agree and the consultants strongly agree that other appropriate consultants (e.g., the patient’s pace- the anesthesiologist should collaborate with the magnetic maker specialist or cardiologist, the diagnostic radiolo- resonance (MR) technologist and/or facility biomedical en- gist, the device manufacturer).** gineer to determine and demarcate the optimal and safe Other implanted electronic devices also pose a hazard location of movable equipment in relation to the gauss lines in the MRI environment. These devices and associated within the MRI suite. They both strongly agree that, be- wiring may transfer energy during the MRI scan, causing cause line of sight within the bore will vary depending on tissue damage, malfunction of the device, image arti- the facility, the anesthesiologist should choose a location or facts, and device displacement. MRI may be performed position for optimal patient observation and vigilance dur- on a limited basis for patients with certain implanted ing delivery of care, whether in zone III or IV. Finally, they electronic devices (e.g., deep brain stimulators, vagal both strongly agree that the anesthesiologist should pre- nerve stimulators, phrenic nerve stimulators, wire-con- pare a plan for rapidly summoning additional personnel in taining thermodilution catheters, cochlear implants). In the event of an emergency. consultation with the referring physician, the radiologist Advisory Statements. For every case, the anesthesiol- responsible for the procedure, and the neurosurgeon, ogist should prepare, with support personnel, a plan for the anesthesiologist should ensure that the presence of providing optimal anesthetic care within the special envi- the device has been noted and determined to be MRI ronment of the MRI suite. In addition to addressing the safe/conditional before imaging of these patients. medical needs of the patient, features of the plan should include (1) requirements of the scan and personnel needs, (2) IV. Preparation positioning of equipment, (3) special requirements or unique Preparation consists of determining and implement- issues of patient or imaging study, (4) positioning of the anes- ing an individualized anesthetic plan before the MRI thesiologist and the patient, and (5) planning for emergencies. procedure begins. In addition to the anesthetic plan, 1. The anesthesiologist should communicate with the preparation includes a plan for optimal positioning of radiology personnel to determine the requirements for the scan (e.g., duration of the scan, position of the See US Food and Drug Administration alert. Available at: http://www.fda.gov/ patient or area of the body in the scanner, positioning CDER/Drug/InfoSheets/HCP/gcca_200705.htm. Accessed October 17, 2008. of receiver coils, need for periods of paused respira- # Equipment is categorized as safe, unsafe, or conditional for use in the MRI environment. MRI safe equipment is identified by the American Society for tion). The anesthesiologist should communicate with Testing and Materials as having no ferromagnetic parts or radiofrequency inter- other anesthesia team members regarding individual ference. MRI unsafe equipment is identified as having ferromagnetic parts or being affected by radiofrequency interference. MRI conditional equipment may be safe in roles for anesthetic care. certain locations of the suite depending on gauss line locations, but cannot be 2. The anesthesiologist should collaborate with the MR identified as having no ferromagnetic parts (see American Society for Testing and Materials Practice Standards F2503, F2119, and F2052, www.astm.org). In the past, technologist and/or facility biomedical engineer to equipment was described as MRI compatible, but because the safety of this equip- determine and demarcate the optimal and safe loca- ment depended on the particular MRI environment, the word conditional now applies. tion of movable equipment in relation to the gauss ** American Society of Anesthesiologists: Practice advisory for the periopera- lines within the MRI suite. tive management of patients with cardiac rhythm management devices: Pace- 3. Because line of sight within the bore will vary de- makers and implantable cardioverter–defibrillators. ANESTHESIOLOGY 2005; 103: 186–98. pending on the facility, the anesthesiologist should

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choose a location or position for optimal patient in zone IV are safe/conditional for the scan, and (3) a observation and vigilance during delivery of care, monitor should be available to view vital signs from zone whether in zone III or IV. In particular, anesthesiolo- III when the anesthesia care provider is not in zone IV. gists should have (1) a clear line of sight of the patient Advisory Statements. MRI patients should be moni- and physiologic monitors, whether by direct observa- tored in a manner consistent with the ASA Standards for tion or by video camera; (2) anesthetic delivery equip- Basic Anesthetic Monitoring. Anesthesiologists should ment located for optimal control of anesthetic depth be familiar with the expected limitations of available and rapid intervention; and (3) access to hospital monitoring equipment. The Task Force notes that infor- information systems integral to patient care. In pre- mation from electrocardiograms may be limited because paring for positioning, the anesthesiologist should of superimposed voltages from blood flow in the high take into account potential electromagnetic and au- magnetic field (e.g., ST-segment interpretation may be ditory hazards. unreliable, even with highly filtered monitors). The an- 4. Anesthesiologists should prepare a plan for rapidly esthesiologist should make sure that all monitors used in summoning additional personnel in the event of an zone IV are safe/conditional for the scan. A monitor emergency. Because the MRI suite is frequently lo- should be available to view vital signs from zone III cated in an isolated area of the facility, the anesthesi- when the anesthesia care provider is not in zone IV. ologist should ensure that (1) emergency equipment Additional care should be taken in positioning electro- and drugs are immediately accessible; (2) emergency cardiographic and other monitor leads to eliminate communication (e.g., phone or code button) is imme- burns, even with nonferromagnetic leads. diately available; and (3) an evacuation plan is in Anesthetic Care. Observational studies report a high place, including an appropriate location outside the rate of success in imaging of sedated patients or patients to scan room (zone IV) for resuscitation. This location whom light anesthesia is administered.107–112 However, should be complete with physiologic monitors, oxy- motion artifacts may still occur.113–115 [Category B2 evi- gen, suction, and other appropriate resuscitation dence] Observational studies and case reports also indicate equipment. Monitoring requirements, airway man- that sedation or light anesthesia may be associated with agement, and emergency preparedness are additional respiratory depression, oxygen desaturation, bronchos- features that should be included in the preparation pasm, drowsiness, agitation, and vomiting.99,108–113,116–128 and planning for an MRI scan, and are addressed in [Category B2 evidence] The Task Force believes that auto- section V below. mated apnea monitoring (by detection of exhaled carbon dioxide or other means) may decrease risks during both V. Patient Management during MRI moderate and deep sedation. Features of safe patient management during MRI proce- Both the consultants and the ASA members strongly dures include (1) monitoring, (2) anesthetic care, (3) air- agree that, in general, because MRI is a nonpainful pro- way management, and (4) management of emergencies. cedure, lighter levels of anesthesia may be appropriate, Monitoring. Safe monitoring conditions include (1) recognizing that institutional circumstances, patient the use of MRI-safe/conditional monitors, (2) remote characteristics, and anesthesiologist preference may monitoring, and (3) compliance with ASA standards.98 warrant more aggressive airway management and deeper Three observational studies indicate that the use of anesthetic levels. They both strongly agree that anesthe- MRI-compatible monitoring equipment resulted in no siologists should ensure that patients who receive mod- radiofrequency interference, interruptions in scanning, erate or deep sedation are monitored in a manner con- or artifacts.99–101 [Category B2 evidence] Five observa- sistent with their institution’s protocol for monitoring tional studies demonstrate that remote monitoring for similarly sedated patients elsewhere in the facility. In heart rate, blood pressure, auscultation, respiration, and addition, they both strongly agree that equipment and chest wall movement can be performed safely and effec- drugs for anesthetic care in the MRI suite should mirror tively.100,102–105 [Category B2 evidence] One observa- what is available in the operating room. Both the con- tional study reported that compliance with the ASA Stan- sultants and the ASA members are equivocal that, when dards for Basic Anesthetic Monitoring can be obtained, an MRI-safe/conditional anesthesia machine is not avail- provided that the monitoring equipment is properly able, inhalation anesthetics may be administered from an tested before MRI.106 [Category B2 evidence] anesthesia machine inside zone III via an elongated The consultants and ASA members both strongly agree circuit through a wave guide. Finally, both the consult- that MRI patients should be monitored in a manner ants and the ASA members agree that, if total intravenous consistent with the ASA Standards for Basic Anesthetic anesthesia is used, it should be administered by using (1) Monitoring. In addition, they both strongly agree that (1) MRI-safe/conditional pumps in zone IV, (2) traditional anesthesiologists should be familiar with the expected (i.e., MRI-unsafe) pumps in zone III with intravenous limitations of available monitoring equipment, (2) the tubing passed through a wave guide, or (3) periodic anesthesiologist should make sure that all monitors used bolus injections in zone III or IV.

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Advisory Statements. Although lighter levels of an- Alternatively, if total intravenous anesthesia is used, it esthesia may be appropriate during an MRI scan, the should be administered by using (1) MRI-safe/conditional anesthesiologist should be aware that these lighter levels pumps in zone IV, (2) traditional (i.e., MRI unsafe) pumps may result in airway complications (e.g., laryngospasm, in zone III with intravenous tubing passed through a wave coughing, other airway compromise) that may necessi- guide, or (3) periodic bolus injections in zone III or IV. tate interruption of the scan for urgent treatment and alter- Although an anesthesia machine may not be required for ation of anesthetic depth. Institutional circumstances, pa- the administration of total intravenous anesthesia, there tient characteristics, and anesthesiologist preference may must be equipment immediately available for the adminis- warrant more aggressive airway management and deeper tration of positive-pressure ventilation with oxygen. anesthetic levels. Airway Management. Unique features of airway man- Anesthesiologists should ensure that patients who re- agement during an MRI scan include (1) the limited ceive moderate or deep sedation are monitored in a accessibility of the patient’s airway and (2) the difficulty manner consistent with their institution’s protocol for of conducting visual and auditory assessments of the monitoring similarly sedated patients elsewhere in the patient. The literature is silent regarding the management facility. Monitoring of exhaled carbon dioxide should be of airway problems (e.g., obstruction, secretions, laryngo- spasm, apnea and hypoventilation) during an MR scan. considered for all patients receiving deep sedation and [Category D evidence] In addition, the literature is silent for patients whose ventilation cannot be directly ob- regarding whether the use of an endotracheal tube or served during moderate sedation.†† The Task Force cau- laryngeal mask airway improves outcomes for patients at tions that, because ventilation and oxygenation are sep- risk of airway compromise during MRI. [Category D evi- arate though related physiologic processes, monitoring dence] oxygenation by pulse oximetry is not a substitute for Both the consultants and the ASA members strongly monitoring ventilatory function. agree that the anesthesiologist should have an advance Equipment and drugs for anesthetic care in the MRI plan in place to deal with instrumentation of the airway suite should mirror what is available in other anesthetiz- and common airway problems when patients are in an ing locations, including (1) an integrated anesthesia ma- MRI environment. Both the consultants and the ASA chine, medical gases, and waste anesthesia gas disposal members strongly agree that, if the patient is at risk for or gas scavenging, when inhalational anesthesia is ad- airway compromise, more aggressive airway manage- ministered; (2) suction; (3) adequate electrical outlets ment should be instituted because the patient’s airway and lighting; and (4) storage areas for equipment and may be less accessible when the patient is in the scan- drugs. The Task Force recognizes that physical plant ner. Both the consultants and the ASA members strongly variability exists among institutions.‡‡ Equipment used agree that (1) complex airway management (e.g., fiber- in the MRI suite should be appropriate for the age and optic intubation) should be performed in a controlled size of the patient. environment outside of zone IV, (2) alternative airway Magnetic resonance imaging–safe/conditional anesthe- devices should be immediately available in the MRI suite, sia machines are always preferred for use in an MRI and (3) suction equipment should be immediately acces- facility.§§ However, when an MRI-safe/conditional anes- sible to the patient’s airway at all times. thesia machine is not available, inhalational anesthetics Advisory Statements. The anesthesiologist should can be administered from an anesthesia machine inside have an advance plan in place to deal with instrumenta- zone III via an elongated circuit through a wave guide. tion of the airway and common airway problems (e.g., Although this method of anesthetic delivery was com- obstruction, secretions, laryngospasm, apnea and hy- monplace before the commercial manufacture of MRI- poventilation) when patients are in an MRI environment. safe/conditional anesthesia machines, this practice is in- If the patient is at risk for airway compromise, more herently cumbersome and may be prone to more aggressive airway management (e.g., use of a endotra- possibilities for mishaps than the use of an anesthesia cheal tube or laryngeal mask airway) should be instituted machine specifically designed for the MRI environment. because the patient’s airway may be less accessible when the patient is in the scanner. Complex airway management (e.g., fiberoptic intubation) should be per- †† American Society of Anesthesiologists: Practice guidelines for sedation and analgesia by non-anesthesiologists: An updated report. ANESTHESIOLOGY 2002; 96: formed in a controlled environment outside of zone IV. 1004–17. Alternative MRI-safe/conditional airway devices should ‡‡ When remodeling or building a new facility, input from the anesthesiologist be immediately available in the MRI suite. Suction equip- is critical. ment should be immediately accessible to the patient’s §§ An MRI facility that is newly built or that undergoes a major renovation should have an MRI-safe/conditional anesthesia machine. airway at all times. A wave guide is a copper-lined conduit with a specific length and diameter Management of Emergencies. Emergencies in the that maintains radiofrequency isolation of the magnet room installed during construction of the MRI suite. Wires or conducting material act as an antenna and MR suite include (1) medical emergencies (e.g., cardio- should not be passed through a wave guide. pulmonary arrest) and (2) environmental emergencies (e.g.,

Anesthesiology, V 110, No 3, Mar 2009 PRACTICE ADVISORY 467 quench, fire, projectiles). The remote location of the scan- When a fire occurs in the MRI suite, team members ner within the facility may delay response of support per- should perform their preassigned fire management task sonnel or availability of equipment during an emergency. as quickly as possible, in accordance with the ASA Prac- The literature is insufficient regarding the manage- tice Advisory for the Prevention and Management of ment of medical emergencies (e.g., cardiopulmonary Operating Room Fires. If a team member cannot rapidly arrest) or quench in the MR suite. [Category D evi- perform his or her task in the predetermined order, dence] One case report indicates that a fire occurring other team members should perform their tasks without on the patient was managed by extinguishing the waiting. When a team member has completed a preas- flames, discontinuing the scan, and immediately re- signed task, he or she should help other members per- moving the patient from the bore.45 Two case reports form tasks that are not yet complete. of projectile nitrous oxide or oxygen tanks indicate In the case of projectile emergencies, team members that the emergency was managed by removing pa- should perform their institution’s protocol in reaction tients from zone IV and instituting a controlled to this occurrence. If possible, immediately remove the quench.53,54 [Category B3 evidence] patient from zone IV and discontinue the scan. If the Both the consultants and the ASA members strongly patient is injured, proceed with medical emergency man- agree that when a patient has a medical emergency in agement as indicated above. A controlled quench may be the MRI scanner, the following should occur: (1) initiate necessary to remove the patient from the bore. cardiopulmonary resuscitation, when needed, while im- A quench occurs when a superconducting magnet mediately removing the patient from zone IV; (2) call for turns resistive and catastrophically releases all of the help; and (3) transport the patient to a previously des- stored energy as heat, boiling off the stored cryogens as ignated safe location in proximity to the MRI suite. In gas. The most common cause of quench is an intentional addition, they both strongly agree that the designated shutdown of the magnet for a life-threatening emergency. safe location should contain the following resuscitation Quench may also be the consequence of an unintentional equipment: (1) a defibrillator; (2) vital signs monitors; shutdown. If not properly vented, a quench can result in and (3) a code cart that includes resuscitation drugs, the complete dissipation of oxygen in zone IV, risking airway equipment, oxygen, and suction. The consultants hypoxia to the patient and MRI personnel. In addition, and ASA members both strongly agree that when a fire entrance to zone IV may not be possible because of high occurs in the MRI suite, team members should perform pressure caused by escaping gases, making it impossible to their preassigned fire management tasks as quickly as open the door into zone IV. When a quench occurs, team possible, in accordance with the ASA Practice Advisory members should perform their institution’s protocol in for the Prevention and Management of Operating Room reaction to this occurrence. If possible, (1) immediately Fires.129 The ASA members agree and the consultants remove the patient from zone IV and (2) immediately strongly agree that, when a quench occurs, team mem- administer oxygen to the patient. bers should perform their institution’s protocol in reac- Powerful static magnetic fields may persist after a tion to this occurrence. In addition, the ASA members quench, and therefore the usual precautions apply when agree and the consultants strongly agree that, when a entering zone IV. Emergency response personnel should quench occurs, if possible, (1) the patient should be be restricted from entering zone IV during any environ- removed from zone IV immediately and (2) oxygen mental emergency because of the persistent magnetic field. should be administered to the patient immediately. Fi- nally, both the consultants and the ASA members agree VI. Postprocedure Care that, because powerful static magnetic fields may persist The literature is insufficient to determine whether after a quench or fire, emergency response personnel postprocedure care consistent with that provided for should be restricted from entering zone IV. other areas of the institution reduces the frequency of Advisory Statements. Medical emergencies may be adverse events. [Category D evidence] difficult to manage while the patient is in the MRI scanner. The ASA members agree and the consultants strongly When a patient has a medical emergency (e.g., cardiopul- agree that the anesthesiologist should collaborate with monary arrest) in the MRI scanner, the following should the radiologist and other staff in the postanesthetic care occur: (1) immediately remove the patient from zone IV of the patient. Finally, both the consultants and the ASA while initiating cardiopulmonary resuscitation, if indicated; members strongly agree that (1) patients receiving seda- (2) call for help; and (3) transport the patient to a previ- tion or anesthesia within the MRI suite should have ously designated safe area for resuscitation that is not in access to postanesthetic care consistent with that pro- zone IV. This location should be as close to zone IV as vided in other areas of the institution; (2) in all situations, possible so as not to delay resuscitation efforts, and should intensive care and recovery areas should include access contain the following resuscitation equipment: a defibrilla- to vital signs monitors, oxygen, suction, and trained tor; vital signs monitors; and a code cart that includes personnel; and (3) patients should be given written dis- resuscitation drugs, airway equipment, oxygen, and suction. charge instructions.

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109. Manuli MA, Davies L: Rectal methohexital for sedation of children during Appendix 1: Facility Levels for MRI Suites imaging procedures. AJR Am J Roentgenol 1993; 160:577–80 110. Slovis TL, Parks C, Reneau D, Becker CJ, Hersch J, Carver CD, Ross RD, Tech K, Towbin RB: Pediatric sedation: Short-term effects. Pediatr Radiol 1993; This Advisory categorizes MRI facilities into three general levels accord- 23:345–8 ing to the anticipated level of patient care required. These levels describe 111. Volle E, Park W, Kaufman HJ: MRI examination and monitoring of the physical plant, technical infrastructure, and resources needed to de- pediatric patients under sedation. Pediatr Radiol 1996; 26:280–1 112. Shorrab AA, Demain AD, Atallah MM: Multidrug intravenous anesthesia liver patient care according to standards already established by the ASA for children undergoing MRI: A comparison with general anesthesia. 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Bloomfield EL, Masaryk TJ, Caplin A, Obuchowski NA, Schubert A, medical support personnel on site, although some level 1 facilities may Hayden J, Ebrahim ZY, Ruggieri PM, Goske MJ, Ross JS: Intravenous sedation for provide such services or equipment. Level 1 facilities do not contain MR imaging of the brain and spine in children: Pentobarbital versus propofol. suitable equipment or infrastructure for the care of critical patients, Radiology 1993; 186:93–7 infants, emergency patients, patients needing anesthesia or sedation, 117. Bluemke DA, Breiter SN: Sedation procedures in MR imaging: Safety, effectiveness, and nursing effect on examinations. Radiology 2000; 216:645–52 or other patients with high-risk medical conditions. 118. Connor L, Burrows PE, Zurakowski D, Bucci K, Gagnon DA, Mason KP: Effects of IV pentobarbital with and without fentanyl on end-tidal carbon dioxide levels during deep sedation. AJR Am J Roentgenol 2003; 181:1691–4 Level II: Facilities That Image Patients Requiring 119. De Sanctis Briggs V: Magnetic resonance imaging under sedation in newborns and infants: A study of 640 cases using sevoflurane. Paediatr Anaesth Any Level of Anesthesia or Critical Care, Including 2005; 15:9–15 Noninvasive or Invasive Monitoring and Life 120. Malviya S, Voepel-Lewis T, Eldevik OP, Rockwell DT, Wong JH, Tait AR: Support Sedation and general anaesthesia in children undergoing MRI and CT: Adverse events and outcomes. Br J Anaesth 2000; 84:743–8 Facilities with this designation provide imaging for patients receiv- 121. Mason KP, Sanborn P, Zurakowski D, Karian VE, Connor L, Fontaine PJ, ing sedation or anesthesia; intensive care patients requiring continuous Burrows PE: Superiority of pentobarbital versus chloral hydrate for sedation in monitoring, drug infusions, or mechanical ventilation; and patients infants during imaging. Radiology 2004; 230:537–42 needing emergent scans. Non-MRI personnel (e.g., anesthesiologists, 122. Mason KP, Zurakowski D, Connor L, Karian VE, Fontaine PJ, Sanborn PA, Burrows PE: Infant sedation for MR imaging and CT: Oral versus intravenous emergency physicians, intensivists, house staff, nurses, nurse practitio- pentobarbital. Radiology 2004; 233:723–8 ners) are typically present to provide patient care. Patient monitoring 123. Merola C, Albarracin C, Lebowitz P, Bienkowski RS, Barst SM: An audit of systems designated as safe/conditional for zone IV are required in these adverse events in children sedated with chloral hydrate or propofol during facilities. Level II facilities provide medical gases (oxygen, nitrous imaging studies. Paediatr Anaesth 1995; 5:375–8 124. Pershad J, Wan J, Anghelescu DL: Comparison of propofol with pento- oxide, air), patient suction, and evacuation of anesthetic gases. Back up barbital/midazolam/fentanyl sedation for magnetic resonance imaging of the oxygen resources in nonferromagnetic (e.g., aluminum) canisters are brain in children. Pediatrics 2007; 120:e629–36 also available. Finally, oxygen and suction are readily available in zone 125. Sanborn PA, Michna E, Zurakowski D, Burrows PE, Fontaine PJ, Connor II or III for patients who need to be evacuated from zone IV for L, Mason KP: Adverse cardiovascular and respiratory events during sedation of pediatric patients for imaging examinations. Radiology 2005; 237:288–94 emergent resuscitation. 126. Sury MRJ, Harker H, Thyomas ML: Sevoflurane sedation in infants under- going MRI: A preliminary report. Paediatr Anaesth 2005; 15:16–22 127. Vade A, Sukhani R, Dolenga M, Habisohn-Schuck C: Chloral hydrate Level III: Facilities That Provide Imaging for sedation of children undergoing CT and MR imaging: Safety as judged by Amer- Operative Procedures ican Academy of Pediatrics guidelines. AJR Am J Roentgenol 1995; 165:905–9 Facilities with this designation contain all resources (i.e., physical 128. Woodthorpe C, Trigg A, Alison G, Sury M: Nurse led sedation for paedi- atric MRI: Progress and issues. Paediatr Nurs 2007; 19:14–8 plant and technical infrastructure) commensurate with level II facilities 129. American Society of Anesthesiologists: Practice advisory for the preven- and, in addition, provide an operative team of non-MRI personnel with tion and management of operating room fires. ANESTHESIOLOGY 2008; 108:786–801 the appropriate surgical tools and equipment (e.g., availability of addi- 130. American Society of Anesthesiologists: Standards for postanesthesia care, tional gases such as nitrogen to power surgical equipment). All legal ASA Standards, Guidelines and Statements. October 2007. Available at: http:// www.asahq.org/publicationsAndServices/standards/36.pdf. Accessed October codes and standards for operating rooms (such as air turnover and 17, 2008 ventilation) apply.

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Appendix 2: Primary Findings of the ● Anesthesiologists should work with their institutions to properly Advisory Task Force identify and label anesthesia-related equipment according to conven- tion (safe, unsafe, or conditional) for each MRI scanner.

● For each MRI location, anesthesiologists should determine the safety I. Education and effectiveness of the equipment needed by the patient during the ● All anesthesiologists should have general safety education on the procedure. unique physical environment of the MRI scanner, and specific edu- ؠ Care should be taken to ensure that the patient’s equipment does cation regarding the specific features of individual scanners within not interfere with image acquisition or quality. their institution. ● Cardiac pacemakers and implantable cardioverter–defibrillators are ؠ Education should emphasize safety for entering zones III and IV, with generally contraindicated for MRI. special emphasis on hazards in this environment and effects on mon- ؠ When MRI is considered essential by the referring physician and itoring capabilities. consulting radiologist, a plan for managing these patients during ؠ Education should address potential health hazards (e.g., high decibel the scan should be developed in collaboration with the ordering levels and high-intensity magnetic fields). physician, medical director or on-site radiologist, and other appro- ؠ Education should address necessary precautions to deal with the priate consultants (e.g., patient’s pacemaker specialist or cardiolo- specific field strength and the safety of the MRI scanners within their gist, diagnostic radiologist, device manufacturer). institutions. ● MRI may be performed on a limited basis for patients with certain ؠ Education should include information regarding ferromagnetic items implanted electronic devices (e.g., deep brain stimulators, vagal (e.g., stethoscopes, pens, wallets, watches, hair clips, name tags, pag- nerve stimulators, phrenic nerve stimulators, wire-containing ther- ers, cell phones, credit cards, batteries) and implantable devices (e.g., modilution catheters, cochlear implants). spinal cord stimulators, implanted objects) that should not be brought -ؠ In consultation with the referring physician, the radiologist respon into zone III or IV of the MRI suite or should be brought in with sible for the procedure, and the neurosurgeon, the anesthesiologist caution. should ensure that the presence of the device has been noted and ● Anesthesiologists should work in collaboration with radiologists, determined to be MRI safe/conditional before imaging of these technologists, and physicists within their institutions to ensure that patients. the above topics are included in their safety training programs.

● Education should include how to safely respond to code blue situa- tions in zones III and IV, and this information should be integrated IV. Preparation into protocols for the designated code blue team. ● For every case, the anesthesiologist should prepare, with support personnel, a plan for providing optimal anesthetic care within the II. Screening of Anesthesia Care Providers and special environment of the MRI suite. Ancillary Support Personnel ؠ In addition to addressing the medical needs of the patient, features ● The anesthesiologist should work in collaboration with the MRI of the plan should include (1) requirements of the scan and per- medical director or designee (e.g., safety officer) to ensure that all sonnel needs, (2) positioning of equipment, (3) special require- anesthesia team personnel entering zone III or IV have been screened ments or unique issues of patient or imaging study, (4) positioning for the presence of ferromagnetic materials, foreign bodies, and of the anesthesiologist and the patient, and (5) planning for emer- implanted devices. gencies.

● The anesthesiologist should communicate with the radiology personnel III. Patient Screening to determine the requirements for the scan (e.g., duration of the scan, ● For every case, the anesthesiologist should communicate with the position of the patient or area of the body in the scanner, positioning of patient, referring physician, and radiologist to determine whether the receiver coils, need for periods of paused respiration). patient: ● The anesthesiologist should communicate with other anesthesia .ؠ Presents with a high-risk medical condition (e.g., neonatal status or team members regarding individual roles for anesthetic care prematurity, intensive or critical care status, impaired respiratory ● The anesthesiologist should collaborate with the MR technologist function; hemodynamic instability and vasoactive infusion re- and/or facility biomedical engineer to determine and demarcate the quirements; comorbidities such as obesity and peripheral vascu- optimal and safe location of movable equipment in relation to the lar disease) gauss lines within the MRI suite. ؠ Requires equipment (e.g., physiologic or invasive monitors; in- ● The anesthesiologist should choose a location or position for optimal tubation, oxygenation, or ventilation equipment) patient observation and vigilance during delivery of care, whether in .ؠ Has been screened for implanted devices (e.g., pacemakers, cardio- zone III or IV verter–defibrillators, nerve stimulators) ؠ Anesthesiologists should have (1) a clear line of sight of the ؠ Has been screened for implanted ferromagnetic items (e.g., surgical patient and physiologic monitors, whether by direct observation clips, prosthetic heart valves) or by video camera; (2) anesthetic delivery equipment located ;ؠ Has been screened for the presence of imbedded foreign bodies (e.g., for optimal control of anesthetic depth and rapid intervention orbital iron filings, eyeliner tattoos) and (3) access to hospital information systems integral to patient

● The anesthesiologist should communicate with the technologist to en- care. sure that the patient has been screened for the presence of foreign bodies ؠ In preparing for positioning, the anesthesiologist should take on the patient (e.g., pierced jewelry, rings) before entering zone III. into account potential electromagnetic and auditory hazards.

● If a patient presents with a high-risk medical condition, the anesthe- ● Anesthesiologists should prepare a plan for rapidly summoning addi- siologist should collaborate with all participants, including the refer- tional personnel in the event of an emergency. ring physician, radiologist, and technologist, to determine how the ؠ The anesthesiologist should ensure that (1) emergency equipment and patient will be managed during the MRI procedure. drugs are immediately accessible; (2) emergency communication (e.g., ؠ Anticipated changes in level of sedation, muscle relaxation, or phone or code button) is immediately available; and (3) an evacuation ventilation may also place a patient in a high-risk situation. plan is in place, including an appropriate location outside the scan

● For patients with acute or severe renal insufficiency, the anesthesi- room (zone IV) for resuscitation. ologist should not administer gadolinium because of the increased - This location should be complete with physiologic monitors, oxy- risk of nephrogenic systemic fibrosis. gen, suction, and other appropriate resuscitation equipment.

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V. Patient Management during MRI (e.g., obstruction, secretions, laryngospasm, apnea and hypoventi- lation) when patients are in an MRI environment. ● Monitoring ؠ If the patient is at risk for airway compromise, more aggressive ؠ MRI patients should be monitored in a manner consistent with the airway management (e.g., use of a endotracheal tube or laryngeal ASA Standards for Basic Anesthetic Monitoring. mask airway), should be instituted because the patient’s airway ؠ The anesthesiologist should be familiar with the expected limitations may be less accessible when the patient is in the scanner. of available monitoring equipment. ؠ Complex airway management (e.g., fiberoptic intubation) should - Information from electrocardiograms may be limited due to super- be performed in a controlled environment outside of zone IV. imposed voltages from blood flow in the high magnetic field (e.g., ؠ Alternative airway devices should be immediately available in the ST-segment interpretation may be unreliable, even with highly fil- MRI suite. tered monitors). -ؠ Suction equipment should be immediately accessible to the pa ؠ The anesthesiologist should make sure that all monitors used in zone tient’s airway at all times. IV are safe/conditional for the scan. ؠ A monitor should be available to view vital signs from zone III when VI. Management of Emergencies the anesthesia care provider is not in zone IV. ● When a patient has a medical emergency (e.g., cardiopulmonary -ؠ Additional care should be taken in positioning electrocardiogram and arrest) in the MRI scanner, the following should occur: (1) Immedi other monitor leads to eliminate burns, even with nonferromagnetic ately remove the patient from zone IV while initiating cardiopulmo- leads. nary resuscitation, if indicated; (2) call for help; and (3) transport the ● Anesthetic care patient to a previously designated safe area for resuscitation that is .ؠ Although lighter levels of anesthesia may be appropriate during not in zone IV an MRI scan, the anesthesiologist should be aware that these ؠ This location should be as close to zone IV as possible so as not to lighter levels may result in airway complications (e.g., laryngo- delay resuscitation efforts, and should contain the following resus- spasm, coughing, or other airway compromise), which may citation equipment: a defibrillator, vital signs monitors, and a code necessitate interruption of the scan for urgent treatment and cart that includes resuscitation drugs, airway equipment, oxygen, alteration of anesthetic depth. and suction. - Institutional circumstances, patient characteristics, and anes- ● When a fire occurs in the MRI suite, team members should perform thesiologist preference may warrant more aggressive airway their preassigned fire management task as quickly as possible, in management and deeper anesthetic levels. accordance with the ASA Practice Advisory for the Prevention and .ؠ Anesthesiologists should ensure that patients who receive mod- Management of Operating Room Fires erate or deep sedation are monitored in a manner consistent ؠ If a team member cannot rapidly perform his or her task in the with their institution’s protocol for monitoring similarly sedated predetermined order, other team members should perform their patients elsewhere in the facility. tasks without waiting. ؠ Monitoring of exhaled carbon dioxide should be considered for ؠ When a team member has completed a preassigned task, he or all patients receiving deep sedation and for patients whose she should help other members perform tasks that are not yet ventilation cannot be directly observed during moderate seda- complete. tion. ● In the case of projectile emergencies, team members should perform .ؠ Monitoring oxygenation by pulse oximetry is not a substitute for their institution’s protocol in reaction to this occurrence ؠ monitoring ventilatory function. If possible, immediately remove the patient from zone IV and .ؠ Equipment and drugs for anesthetic care in the MRI suite should discontinue the scan ؠ mirror what is available in other anesthetizing locations, includ- If the patient is injured, proceed with medical emergency manage- ing (1) an integrated anesthesia machine, medical gases, and waste ment as indicated above. ؠ anesthesia gas disposal or gas scavenging, when inhalational anesthe- A controlled quench may be necessary to remove the patient from the bore. sia is administered; (2) suction; (3) adequate electrical outlets and ● When a quench occurs, team members should perform their institu- lighting; and (4) storage areas for equipment and drugs. tion’s protocol in reaction to this occurrence. If possible, (1) imme- ؠ Equipment used in the MRI suite should be appropriate for the age and diately remove the patient from zone IV and (2) immediately admin- size of the patient. ister oxygen to the patient. ؠ MRI-safe/conditional anesthesia machines are always preferred for use ؠ Powerful static magnetic fields may persist after a quench, and in an MRI facility. therefore the usual precautions apply when entering zone IV. - When an MRI-safe/conditional anesthesia machine is not available, ● Emergency response personnel should be restricted from entering inhalational anesthetics can be administered from an anesthesia zone IV during any environmental emergency because of the persis- machine inside zone III via an elongated circuit through a wave tent magnetic field. guide. - If total intravenous anesthesia is used, it should be administered by VII. Postprocedure Care using (1) MRI-safe/conditional pumps in zone IV, (2) traditional (i.e., ● The anesthesiologist should collaborate with the radiologist and MRI unsafe) pumps in zone III with intravenous tubing passed other staff in the postprocedure care of the patient.

through a wave guide, or (3) periodic bolus injections in zone III or ● Patients receiving sedation or anesthesia within the MRI suite should IV. have access to postanesthetic care consistent with that provided in ● Although an anesthesia machine may not be required for the admin- other areas of the institution, including transport to other recovery istration of total intravenous anesthesia, there must be equipment rooms, dedicated intensive care, or recovery areas within the MRI immediately available for the administration of positive pressure suite.

ventilation with oxygen. ● In all situations, intensive care and recovery areas should include access ● Airway management to vital sign monitors, oxygen, suction, resuscitation equipment, and .ؠ The anesthesiologist should have an advance plan in place to deal trained personnel

with instrumentation of the airway and common airway problems ● Patients should be given oral and written discharge instructions.

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Appendix 3: Methods and Analyses 1,200 citations were initially identified, yielding a total of 343 articles that addressed topics related to the evidence linkages and met our For this Advisory, a systematic review and evaluation of the literature criteria for inclusion. After review of the articles, 186 studies did not was conducted, and formal survey opinion data were obtained from provide direct evidence and were subsequently eliminated. A total of experts and ASA members. Informal opinion-based information from 157 articles contained direct linkage-related evidence (see Supplemen- other sources (e.g., open forums, Internet postings) was also used in tal Digital Content 1, which is a complete list of references used to the development of this document. Both the literature evaluation and develop this Advisory, http://links.lww.com/A623).††† No evidence the survey opinion data were based on evidence linkages, or state- linkage contained enough studies with well-defined experimental de- ments regarding potential relations between patient care interventions signs and statistical information to conduct a quantitative analysis (i.e., and safety outcomes in the MRI suite.*** The evidence linkage inter- meta-analysis). ventions are listed below. Interobserver agreement among Task Force members and two meth- odologists was established by interrater reliability testing. Agreement I. Education levels using a ␬ statistic for two-rater agreement pairs were as follows: 1. MRI education for magnet hazards (1) type of study design, ␬ ϭ 0.49–0.85; (2) type of analysis, ␬ ϭ 2. MRI education for monitoring limitations 0.54–0.93; (3) evidence linkage assignment, ␬ ϭ 0.77–1.00; and (4) 3. MRI education for long-term health hazards literature inclusion for database, ␬ ϭ 0.78–1.00. Three-rater chance- II. Screening of Anesthesia Care Providers and Ancillary Support corrected agreement values were (1) study design, Sav ϭ 0.65, Var Personnel (Sav) ϭ 0.009; (2) type of analysis, Sav ϭ 0.69, Var (Sav) ϭ 0.010; (3) 4. Mandatory screening of all personnel entering zone III or IV linkage assignment, Sav ϭ 0.85, Var (Sav) ϭ 0.004; and (4) literature database inclusion, Sav ϭ 0.85, Var (Sav) ϭ 0.013. These values III. Patient Screening represent moderate to high levels of agreement. 5. Patient-related risks for adverse outcomes related to MRI 6. Equipment-related risks for adverse outcomes related to MRI B. Consensus-based Evidence IV. Preparation Consensus was obtained from multiple sources, including (1) survey 7. Planning for the anesthetic care of the patient for the scan opinion from consultants who were selected based on their knowledge 8. Planning for rapidly summoning additional personnel in the or expertise in MRI, (2) survey opinions solicited from active members event of an emergency of the ASA, (3) testimony from attendees of a publicly held open forum V. Patient Management during MRI at two national anesthesia meetings, (4) Internet commentary, and (5) 9. Monitoring during MRI Task Force opinion and interpretation. The survey rate of return was 10. Anesthetic care during MRI 63% (n ϭ 50 of 79) for the consultants, and 989 surveys were received 11. Airway management during MRI from active ASA members. Results of the surveys are reported in tables 2 and 3 and are reported in summary form in the text of the Advisory. VI. Management of Emergencies The consultants were asked to indicate which, if any, of the evi- 12. Medical emergencies dence linkages would change their clinical practices if the Advisory 13. Environmental emergencies was instituted. The rate of return was 29% (n ϭ 23 of 79). The percent VII. Postprocedure Care of responding consultants expecting a change in their practice associ- 14. Postprocedure care consistent with that provided for other ated with each linkage topic was as follows: (1) education, 30%; (2) areas of the institution screening of anesthesia care providers and ancillary support personnel, 13%; (3) patient screening, 26%; (4) preparation,13%; (5) patient man- agement during MRI—monitoring, 4%; (6) patient management during A. State of the Literature MRI—anesthetic care, 0%; (7) patient management during MRI—air- For the literature review, potentially relevant studies were identified way, 0%; (8) patient management during MRI—emergencies, 13%; and via electronic and manual searches of the literature. The literature (9) postprocedure care, 9%. Seventy-four percent indicated that their search covered a 36-yr period from 1973 through 2008. More than clinical practice would not need new equipment, supplies, or training to implement the Practice Advisory. Eighty-five percent indicated that the Advisory would not require ongoing changes in their practice that *** Outcomes for the listed interventions refer to the occurrence of safety- would affect costs. Ninety-five percent of the respondents indicated that based outcomes. the Advisory would have no effect on the amount of time spent on a ††† A complete list of references used to develop this Advisory is also available typical case, and 5% indicated that there would be a 10-min increase in the by writing to the American Society of Anesthesiologists. amount spent on a typical case with the implementation of this Advisory.

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Table 2. Consultant Survey Responses

Percent Responding to Each Item

Strongly Strongly n Agree Agree Uncertain Disagree Disagree

Education 1. All anesthesiologists should have general safety education on the 50 90.0* 10.1 0.0 0.0 0.0 unique physical environment of the MRI scanner 2. All anesthesiologists should have specific education regarding the 50 58.0* 38.0* 2.0 2.0 0.0 features of individual scanners within their institutions 3. All anesthesiologists should work in collaboration with radiologists, 50 80.0* 16.0 2.0 2.0 0.0 technologists, and physicists within their institutions to develop safety training programs Screening of anesthesia care providers and ancillary support personnel 4. The anesthesiologist should work in collaboration with the MRI 50 60.0* 34.0 4.0 2.0 0.0 medical director or designee to ensure that all anesthesia team personnel entering zone III or IV have been properly screened Patient screening 5a. For every case, the anesthesiologist should communicate with the 58.0* 20.0 10.0 10.0 2.0 58.0* patient and radiologist or referring physician to determine whether the patient has a high-risk medical condition 5b. If the patient presents with a high-risk medical condition, the 50 58.0* 26.0 4.0 10.0 2.0 anesthesiologist should collaborate with all participants, including the referring physician, radiologist, and technologist, to determine how the patient will be managed during the MRI procedure 5c. For patients with acute or severe renal insufficiency, the 49 34.7 34.7* 26.5 4.1 0.0 anesthesiologist should not administer gadolinium because of the increased risk of nephrogenic systemic fibrosis 6a. For every case, the anesthesiologist should communicate with the 49 28.6 36.7* 18.4 14.3 2.0 radiologist or referring physician to determine whether the patient requires equipment that may pose a risk during the scan 6b. The anesthesiologist should determine the safety and effectiveness of 50 46.0 34.0* 10.0 10.0 0.0 the equipment needed by the patient during the procedure for each MRI location 6c. Anesthesiologists should work with their institutions to properly 50 74.0* 26.0 0.0 0.0 0.0 identify and label anesthesia-related equipment according to convention (safe, unsafe, or conditional) for each MRI scanner 6d. Care should be taken to ensure that anesthesia equipment does not 50 68.0* 30.0 2.0 0.0 0.0 interfere with image acquisition or quality 7a. In general, MRI should not be performed on patients with implanted 50 22.0 48.0* 14.0 14.0 2.0 electronic devices 7b. When MRI is considered essential by the referring physician and 50 72.0* 26.0 0.0 2.0 0.0 consulting radiologist, a plan for managing a patient with implanted electronic devices during the scan should be developed in collaboration with the referring physician, medical director, or on-site radiologist and other appropriate consultants Preparation 8. For every case, the anesthesiologist should prepare, with support 50 72.0* 26.0 0.0 2.0 0.0 personnel, a plan for providing optimal anesthetic care within the special environment of the MRI suite 9. The anesthesiologist should communicate with the radiology 50 68.0* 30.0 0.0 2.0 0.0 personnel to determine the requirements for the scan (e.g., duration of the scan, position of the patient or area of the body in the scanner, positioning of receiver coils, need for periods of paused respiration) 10. The anesthesiologist should collaborate with the MRI technologist 50 62.0* 34.0 2.0 0.0 2.0 and/or facility biomedical engineer to determine and demarcate the optimal and safe location of movable equipment in relation to the gauss lines within the MRI suite 11. Because line of sight within the bore will vary depending on the 50 64.0* 28.0 8.0 0.0 0.0 facility, the anesthesiologist should choose a location or position for optimal patient observation and vigilance during delivery of care, whether in zone III or IV 12. The anesthesiologist should prepare a plan for rapidly summoning 50 82.0* 18.0 0.0 0.0 0.0 additional personnel in the event of an emergency (continued)

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Table 2. Continued

Percent Responding to Each Item

Strongly Strongly n Agree Agree Uncertain Disagree Disagree

Patient management during MRI Monitoring 13. MRI patients should be monitored in a manner consistent with the 50 72.0* 26.0 2.0 0.0 0.0 ASA “Standards for Basic Anesthetic Monitoring” 14. Anesthesiologists should be familiar with the expected limitations of 50 84.0* 16.0 0.0 0.0 0.0 available monitoring equipment 15. The anesthesiologist should make sure that all monitors used in zone 50 82.0* 12.0 0.0 4.0 2.0 IV are safe/conditional for the scan 16. A monitor should be available to view vital signs from zone IV when 50 78.0* 16.0 6.0 0.0 0.0 the anesthesia care provider is not in zone IV Anesthetic care 17. In general, because MRI is a nonpainful procedure, lighter levels of 50 58.0* 34.0 2.0 6.0 0.0 anesthesia may be appropriate, recognizing that institutional circumstances, patient preference, and anesthesiologist preference may warrant more aggressive airway management and deeper anesthetic levels 18. Anesthesiologists should ensure that patients who receive moderate 50 82.0* 18.0 0.0 0.0 0.0 or deep sedation are monitored in a manner consistent with their institution’s protocol for monitoring similarly sedated patients elsewhere in the facility 19. Equipment and drugs for anesthetic care in the MRI suite should 50 76.0* 18.0 4.0 2.0 0.0 mirror what is available in the OR 20a. When an MRI-safe/conditional anesthesia machine is not available, 50 6.0 30.0 24.0* 34.0 6.0 inhalation anesthetics may be administered from an anesthesia machine inside zone III via an elongated circuit through a wave guide 20b. If total intravenous anesthesia is used, it should be administered by 50 30.0 58.0* 10.0 2.0 0.0 using (1) MRI-safe/conditional pumps in zone IV, (2) traditional (i.e ., MRI-unsafe) pumps in zone III with the intravenous tubing passed through a wave guide, or (3) periodic bolus injections in zone III or IV Airway management 21. The anesthesiologist should have an advance plan in place to deal 50 88.0* 12.0 0.0 0.0 0.0 with instrumentation of the airway and common airway problems when patients are in an MRI environment 22. If the patient is at risk for airway compromise, more aggressive 50 58.0* 34.0 6.0 2.0 0.0 airway management (e.g., use of a tracheal tube or LMA) should be instituted because the patient’s airway may be less accessible when the patient is in the scanner 23. Complex airway management (e.g., fiberoptic intubation) should be 50 76.6* 18.0 6.0 0.0 0.0 performed in a controlled environment outside of zone IV 24. Alternative airway devices should be immediately available in the MRI 50 78.0* 16.0 4.0 2.0 0.0 suite 25. Suction equipment should be immediately accessible to the patient’s 49 91.8* 6.1 0.0 2.1 0.0 airway at all times Management of emergencies 26a. When a patient has a medical emergency (e.g., cardiopulmonary 49 81.6* 18.4 0.0 0.0 0.0 arrest) in the MRI scanner, the following should occur: (1) Initiate CPR, when needed, while immediately removing the patient from zone IV; (2) call for help; and (3) transport the patient to a previously designated safe location in proximity to the MRI suite 26b. The designated safe location should contain the following 49 85.7* 14.3 0.0 0.0 0.0 resuscitation equipment: a defibrillator, vital signs monitors, and a code cart that includes resuscitation drugs, airway equipment, oxygen, and suction 27. When a fire occurs in the MRI suite, team members should perform 49 71.4* 14.3 14.3 0.0 0.0 their preassigned fire management task as quickly as possible, in accordance with the ASA “Practice Advisory for the Prevention and Management of Operating Room Fires” 28a. When a quench occurs, team members should perform their 49 65.3* 28.6 6.1 0.0 0.0 institution’s protocol in reaction to this occurrence (continued)

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Table 2. Continued

Percent Responding to Each Item

Strongly Strongly n Agree Agree Uncertain Disagree Disagree

28b. When a quench occurs, if possible, (1) immediately remove the 49 55.1* 22.5 20.4 2.0 0.0 patient from zone IV and (2) immediately administer oxygen to the patient 29. Because powerful static magnetic fields may persist after a quench or 49 44.9 26.5* 20.4 8.2 0.0 fire, emergency response personnel should be restricted from entering zone IV Postprocedure care 30. The anesthesiologist should collaborate with the radiologist and other 50 62.0* 28.0 0.0 10.0 0.0 staff in the postanesthetic care of the patient 31. Patients receiving sedation or anesthesia within the MRI suite should 50 82.0* 16.0 0.0 2.0 0.0 have access to postanesthetic care consistent with that provided in other areas of the institution 32. In all situations, intensive care and recovery areas should include 50 84.0* 14.0 2.0 0.0 0.0 access to vital sign monitors, oxygen, suction, and trained personnel 33. Patients should be given written discharge instructions 50 66.6* 32.0 2.0 0.0 0.0

* Median. ASA ϭ American Society of Anesthesiologists; CPR ϭ cardiopulmonary resuscitation; LMA ϭ laryngeal mask airway; MRI ϭ magnetic resonance imaging; n ϭ number of consultants who responded to each item; OR ϭ operating room.

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Table 3. American Society of Anesthesiologists Membership Survey Responses

Percent Responding to Each Item

Strongly Strongly n Agree Agree Uncertain Disagree Disagree

Education 1. All anesthesiologists should have general safety education on the 989 73.6* 25.0 1.0 0.2 0.2 unique physical environment of the MRI scanner 2. All anesthesiologists should have specific education regarding the 986 33.7 42.4* 18.4 5.1 0.5 features of individual scanners within their institutions 3. All anesthesiologists should work in collaboration with radiologists, 989 47.0 41.3* 8.1 3.4 0.2 technologists, and physicists within their institutions to develop safety training programs Screening of anesthesia care providers and ancillary support personnel 4. The anesthesiologist should work in collaboration with the MRI medical 988 43.5 45.5* 8.0 2.8 0.2 director or designee to ensure that all anesthesia team personnel entering zone III or IV have been properly screened Patient screening 5a. For every case, the anesthesiologist should communicate with the 988 54.7* 30.6 6.7 6.9 1.2 patient and radiologist or referring physician to determine whether the patient has a high-risk medical condition 5b. If the patient presents with a high-risk medical condition, the 983 53.8* 34.2 4.6 6.4 1.0 anesthesiologist should collaborate with all participants, including the referring physician, radiologist, and technologist, to determine how the patient will be managed during the MRI procedure 5c. For patients with acute or severe renal insufficiency, the 981 23.7 29.5* 42.9 3.7 0.3 anesthesiologist should not administer gadolinium because of the increased risk of nephrogenic systemic fibrosis 6a. For every case, the anesthesiologist should communicate with the 976 36.2 38.1* 10.5 12.9 2.4 radiologist or referring physician to determine whether the patient requires equipment that may pose a risk during the scan 6b. The anesthesiologist should determine the safety and effectiveness of 977 46.9 38.4* 6.7 6.4 1.7 the equipment needed by the patient during the procedure for each MRI location 6c. Anesthesiologists should work with their institutions to properly identify 981 56.6* 38.8 3.0 1.5 0.1 and label anesthesia-related equipment according to convention (safe, unsafe, or conditional) for each MRI scanner 6d. Care should be taken to ensure that anesthesia equipment does not 980 46.2 49.4 3.1 1.0 0.3 interfere with image acquisition or quality 7a. In general, MRI should not be performed on patients with implanted 982 27.8 42.9* 22.2 6.7 0.4 electronic devices 7b. When MRI is considered essential by the referring physician and 979 53.7* 41.6 2.8 1.3 0.6 consulting radiologist, a plan for managing a patient with implanted electronic devices during the scan should be developed in collaboration with the referring physician, medical director, or on-site radiologist and other appropriate consultants Preparation 8. For every case, the anesthesiologist should prepare, with support 977 63.2* 33.6 1.7 1.1 0.4 personnel, a plan for providing optimal anesthetic care within the special environment of the MRI suite 9. The anesthesiologist should communicate with the radiology personnel 980 64.5* 33.1 1.2 1.2 0.0 to determine the requirements for the scan (e.g., duration of the scan, position of the patient or area of the body in the scanner, positioning of receiver coils, need for periods of paused respiration) 10. The anesthesiologist should collaborate with the MRI technologist and/ 974 48.8 43.2* 6.7 1.2 0.1 or facility biomedical engineer to determine and demarcate the optimal and safe location of movable equipment in relation to the gauss lines within the MRI suite 11. Because line of sight within the bore will vary depending on the facility, 982 53.8* 39.3 5.1 1.3 0.5 the anesthesiologist should choose a location or position for optimal patient observation and vigilance during delivery of care, whether in zone III or IV 12. The anesthesiologist should prepare a plan for rapidly summoning 978 70.6* 28.0 1.0 0.4 0.0 additional personnel in the event of an emergency (continued)

Anesthesiology, V 110, No 3, Mar 2009 478 PRACTICE ADVISORY

Table 3. Continued

Percent Responding to Each Item

Strongly Strongly n Agree Agree Uncertain Disagree Disagree

Patient management during MRI Monitoring 13. MRI patients should be monitored in a manner consistent with the ASA 977 73.7* 22.5 1.4 1.8 0.5 “Standards for Basic Anesthetic Monitoring” 14. Anesthesiologists should be familiar with the expected limitations of 978 71.9* 27.8 0.2 0.0 0.1 available monitoring equipment 15. The anesthesiologist should make sure that all monitors used in zone 977 68.3* 27.7 2.4 1.3 0.3 IV are safe/conditional for the scan 16. A monitor should be available to view vital signs from zone IV when the 976 71.6* 24.7 3.5 0.1 0.1 anesthesia care provider is not in zone IV Anesthetic care 17. In general, because MRI is a nonpainful procedure, lighter levels of 976 53.3* 43.3 1.6 1.2 0.5 anesthesia may be appropriate, recognizing that institutional circumstances, patient preference, and anesthesiologist preference may warrant more aggressive airway management and deeper anesthetic levels 18. Anesthesiologists should ensure that patients who receive moderate or 976 66.9* 30.2 1.3 1.1 0.4 deep sedation are monitored in a manner consistent with their institution’s protocol for monitoring similarly sedated patients elsewhere in the facility 19. Equipment and drugs for anesthetic care in the MRI suite should mirror 980 61.4* 33.3 3.3 2.0 0.0 what is available in the OR 20a. When an MRI-safe/conditional anesthesia machine is not available, 975 10.3 22.8 31.0* 29.1 6.9 inhalation anesthetics may be administered from an anesthesia machine inside zone III via an elongated circuit through a wave guide 20b. If total intravenous anesthesia is used, it should be administered by 978 24.0 53.2* 12.0 8.7 2.2 using (1) MRI-safe/conditional pumps in zone IV, (2) traditional (i.e., MRI-unsafe) pumps in zone III with the intravenous tubing passed through a wave guide, or (3) periodic bolus injections in zone III or IV Airway management 21. The anesthesiologist should have an advance plan in place to deal with 979 79.6* 20.1 0.3 0.0 0.0 instrumentation of the airway and common airway problems when patients are in an MRI environment 22. If the patient is at risk for airway compromise, more aggressive airway 981 72.8* 23.0 2.6 1.6 0.0 management (e.g., use of a tracheal tube or LMA) should be instituted because the patient’s airway may be less accessible when the patient is in the scanner 23. Complex airway management (e.g., fiberoptic intubation) should be 981 71.9* 24.5 2.7 1.0 0.0 performed in a controlled environment outside of zone IV 24. Alternative airway devices should be immediately available in the MRI 981 70.2* 26.1 2.5 1.2 0.0 suite 25. Suction equipment should be immediately accessible to the patient’s 978 86.4* 12.8 0.7 0.1 0.0 airway at all times Management of emergencies 26a. When a patient has a medical emergency (e.g., cardiopulmonary arrest) 976 72.2* 25.7 1.8 0.2 0.0 in the MRI scanner, the following should occur: (1) Initiate CPR, when needed, while immediately removing the patient from zone IV; (2) call for help; and (3) transport the patient to a previously designated safe location in proximity to the MRI suite 26b. The designated safe location should contain the following resuscitation 978 79.4* 19.9 0.5 0.1 0.1 equipment: a defibrillator, vital signs monitors, and a code cart that includes resuscitation drugs, airway equipment, oxygen, and suction 27. When a fire occurs in the MRI suite, team members should perform 970 65.4* 30.4 4.5 0.0 0.1 their preassigned fire management task as quickly as possible, in accordance with the ASA “Practice Advisory for the Prevention and Management of Operating Room Fires” 28a. When a quench occurs, team members should perform their 967 49.1 29.7* 21.2 0.0 0.0 institution’s protocol in reaction to this occurrence 28b. When a quench occurs, if possible, (1) immediately remove the patient 963 49.0 27.6* 22.5 0.7 0.1 from zone IV and (2) immediately administer oxygen to the patient (continued)

Anesthesiology, V 110, No 3, Mar 2009 PRACTICE ADVISORY 479

Table 3. Continued

Percent Responding to Each Item

Strongly Strongly n Agree Agree Uncertain Disagree Disagree

29. Because powerful static magnetic fields may persist after a quench or 973 22.3 28.7* 41.0 7.2 0.8 fire, emergency response personnel should be restricted from entering zone IV Postprocedure care 30. The anesthesiologist should collaborate with the radiologist and other 979 41.5 41.5* 4.9 10.5 1.6 staff in the postanesthetic care of the patient 31. Patients receiving sedation or anesthesia within the MRI suite should 981 72.0* 27.1 0.5 0.4 0.0 have access to postanesthetic care consistent with that provided in other areas of the institution 32. In all situations, intensive care and recovery areas should include 977 77.7* 22.3 0.0 0.0 0.0 access to vital sign monitors, oxygen, suction, and trained personnel 33. Patients should be given written discharge instructions 981 53.1* 39.4 5.9 1.5 0.1

* Median. ASA ϭ American Society of Anesthesiologists; CPR ϭ cardiopulmonary resuscitation; LMA ϭ laryngeal mask airway; MRI ϭ magnetic resonance imaging; n ϭ number of American Society of Anesthesiology members who responded to each item; OR ϭ operating room.

Anesthesiology, V 110, No 3, Mar 2009