Anesthesia for Bronchoscopy

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Send Orders of Reprints at [email protected] 6314 Current Pharmaceutical Design, 2012, 18, 6314-6324

Basem B. Abdelmalak*, Thomas R. Gildea‡ and D. John Doyle†

*Associate Professor of Anesthesiology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University. Director, Anesthesia for Bronchoscopic Surgery, Departments of General Anesthesiology and OUTCOMES RESEARCH, Anesthesiology Institute, Cleveland Clinic, Cleveland, Ohio; ‡Staff, Department of Pulmonary, Allergy and Critical Care Medicine & Transplant Center, Head, Section of Bronchoscopy, Respiratory Institute, Cleveland Clinic, Cleveland, Ohio; †Professor of Anesthesiology, Cleveland Clinic Lerner College of Medicine of Case, Western Reserve University; Staff, Department of General Anesthesiology, Anesthesiology Institute, Cleveland Clinic, Cleveland, Ohio Abstract: Bronchoscopic procedures are at times intricate and the patients often very ill. These factors and an airway shared with the pulmonologist present a clear challenge to anesthesiologists. The key to success lies in the understanding of both the underlying pathology and procedure being performed combined with frequent two-way communication between the anesthesiologist and the pulmonologist. Above all, vigilance and preparedness are paramount. Topics discussed in this review include anesthesia for advanced diagnostic procedures as well as for interventional/ therapeutic procedures. The latter includes bronchoscopic tracheal balloon dilation, tracheobronchial stenting, endobronchial electrocautery, bronchoscopic cryotherapy and other techniques. Special situations, such as tracheoesophageal fistula and mediastinal masses, are also considered. Keywords: Airway management, airway lasers, anesthesia, bronchoscopic surgery, EBUS, ENB, metallic stents, silicone stents, bronchoscopy.

INTRODUCTION with the commonly used anesthetic techniques, and skilled in the There has been a recent proliferation in bronchoscopic interven- various airway management options for these often challenging tional procedures leading to an increasing demand for anesthesia patients. services for these often challenging procedures [1]. A number of FREQUENTLY PERFORMED PROCEDURES thoracic surgery procedures such as mediastinal staging, that were traditionally performed in the operating room with an inpatient stay Diagnostic Bronchoscopy, Including Brushings, Washings, and can now be done on an outpatient basis using minimally invasive Biopsies bronchoscopic methods[2]. As a result, a number of facilities have Bronchoscopic examination of the airway allows visual inspec- constructed specially equipped interventional pulmonology suites tion (look for lesions, areas of compression etc.) and diagnostic independent from the ORs. A development of which are the “Hy- procedures (brushings, washings, and biopsies of tracheal and/or brid ORs”, capable of accommodating both advanced diagnostic, bronchial lesions). These are accomplished through either a flexible interventional, and minimally invasive procedures as well as classi- bronchoscope or (less commonly) a rigid bronchoscope. cal open procedures. The intent is to establish centers of excellence To obtain bronchial brushings a brush is advanced to the lesion for these highly specialized procedures, using standardized proto- via the bronchoscope channel either using either direct visualization cols that nevertheless allow for individualized approaches that or (for distant peripheral lesions) fluoroscopy. The lesion is then match clinical conditions. gently brushed, the brush withdrawn, and the brushings transferred Patients presenting for interventional pulmonology procedures onto glass slides for cytological review. Sometimes a special brush often carry high anesthetic risk.[3] Anesthesia providers frequently sealed in a protective catheter is employed to obtain “protected have to deal with the combination of severe lung pathology with brushings” for microbiologic studies. additional multisystem comorbidities such as obesity, diabetes and To obtain bronchial washings, the bronchoscope is passed in the coronary heart disease. During bronchoscopic surgery anesthesiolo- usual manner while isotonic saline (0.9%) is instilled through the gists and pulmonologists must share the airway occasionally with bronchoscopic channel into the target area. Fluid is then aspirated conflicting clinical objectives. (For instance, the pulmonologists into a trap attached to the suction tubing, followed by cytological or may require a motionless operating field, whereas the anesthesiolo- other analysis. gist requires lung movement to maintain oxygenation and ventilation.) A clear method of communicating clinical needs in a respect- Finally, bronchoalveolar lavage (BAL) is commonly performed ful environment is essential. for diagnostic/therapeutic purposes. In BAL aliquots of approxi- mately 20 mL - 40 ml of isotonic saline are administered via the Finally, the challenge of contemporaneous record keeping ex- bronchoscope and then suctioned. An important therapeutic varia- ists due to the dynamic nature of bronchoscopic interventional pro- tion of BAL is therapeutic whole-lung lavage, which is usually cedures. Changing airway conditions and anesthetic requirements done for pulmonary alveolar proteinosis (PAP) [4]. Whole-lung may leave little time for documentation. This may require an auto- lavage is usually performed using a left-sided double-lumen en- mated anesthesia Information Management System (AIMS) or a dotracheal tube so as to allow lung isolation in order to allow venti- second individual focused on this task. lation of one lung while lavaging the other. Compared to BAL, the As a result of these special requirements, it is essential for the infused volumes are enormous - up to 50 L of isotonic saline are anesthesiologist to be conversant with all these procedures, familiar sometimes used. Typically, done on a sequential manner, one lung is lavaged on a single day followed by the other lung a few days *Address correspondence to this author at the Department of General Anes- later, although at the authors’ institution, bilateral therapeutic whole thesiology – E31, Cleveland Clinic, 9500 Euclid Avenue/ E31, Cleveland, lung lavage is often performed in the same setting, on the same day. Ohio, USA 44195; Tel: (216) 444-3746; Fax: (216) 444-2294; E-mail: [email protected]

To obtain endobronchial biopsies, the bronchoscope is passed in the usual manner into the vicinity of the suspicious area. Biopsy forceps are then passed down through the bronchoscope channel, its jaws are opened and closed on the tissue, and the forceps are removed. The obtained tissue is then transferred into a formalin- containing container for fixation. For large tissue samples that cannot pass through the bronchoscope channel, continuous suction is applied to hold the sample in place at the tip of the bronchoscope while the entire bronchoscope is then withdrawn with the tissue sample held at the bronchoscope tip by suction. Attempting transbronchial biopsies involves a higher risk of bleeding and pneumothorax since the lung parenchyma near the pleural surface is typically the target for diagnosing diffuse lung disease while tumors typically have increased vascular supply and may be closer to bronchial artery braches. The appropriate position of a bronchoscope in these types of procedures is wedged in an airway to serve as a bar- rier to any bleeding and to tamponade the otherwise noncompressible biopsy site. Fig. (1). The CRE™ Pulmonary Balloon Dilator system from Boston Scien- tific is used to endoscopically dilate airway strictures. Reprinted with per- Tracheobronchial Balloon Dilation mission, Cleveland Clinic Center for Medical Art & Photography © 2011- 2012. All rights reserved. The most common cause of subglottic or tracheal stenosis is prolonged tracheal intubation, it can also occur after relatively short periods of intubation. This may be, as a result of traumatic intubation, or from other causes (e.g., inhalational injury, previous laryngeal surgery, or as a complication of cervical spine trauma). Wegener's granulomatosis and sarcoidosis are rare conditions causing tracheal and bronchial stenosis that may be encountered in tertiary care centers. In addition, lower airway stenosis related to lung transplantation is not uncommon. in the ideopathic causation is illustrated in a series by Rahman et al. [5], of 115 patients presenting with benign tracheal stenosis, 106 were the result of intubation / mechanical ventilation, while only nine were from other etiologies

(of which four were idiopathic). The procedure for tracheal or bronchial balloon dilation can be performed in a number of ways, for instance using a guide wire and fluoroscopy, or via the bronchoscope’s working channel [6, 7], (Fig. 1). In one method using a flexible fiberoptic bronchoscope, a balloon catheter is threaded over a guidewire and positioned across Fig. (2). Metal and silicone stents are frequently used to support and main- the stenotic area. Under bronchoscopic visualization, the balloon is tain the tracheal lumen, restore integrity of a disrupted airway, and support an airway wall from a compressing mediastinal mass. Here we show a Y- then inflated to several atmospheres pressure for 30 to 120 seconds, shaped silicon stent that has been cut to size, with the edges being smoothed the specifics depending on the manufacturer’s recommendations. using a high-speed sander. Reprinted with permission, Cleveland Clinic Repeat inflation-deflation cycles are performed to achieve the de- Center for Medical Art & Photography © 2011-2012. All rights reserved. sired result. Apnoea is required during the periods of balloon inflation (when treating tracheal and not bronchial stenosis) and some desaturation may occur. Limiting the inflation time. The duration of apnea until this occurs depends upon age, severity of underlying lung disease, comorbidity, and body habitus. Not infrequently, the procedure is used in conjunction with other techniques (dilation using a rigid bronchoscope, cryotherapy, Nd: Yag laser ablation, stent placement).

Potential procedure complications include bleeding, perforation, wall injury or rupture (often resulting in pneumomediastinum), pneumothorax, mediastinitis, chest pain, bronchospasm, and atelec- tasis.

Tracheobronchial Stenting In the last two decades, considerable progress has been made in Fig. (3). Rigid bronchoscope with ventilating sidearm. Note the use of wet the endoscopic management of central airway obstruction. In par- gauze packing around the rigid bronchoscope barrel to minimize leakage ticular, the use of new types of self-expanding metallic stents around the bronchoscope. Reprinted with permission, Cleveland Clinic (SEMS and hybrid stents) placed bronchoscopically has provided Center for Medical Art & Photography © 2011-2012. All rights reserved. new clinical options [8]. Metal, hybrid and silicone stents (Fig. 2) are frequently used to support and maintain the tracheal lumen, Airway Laser restore integrity of a disrupted airway, and support an airway wall Nd:YAG, CO2, YAP and argon lasers are generally used to from a compressing mediastinal mass. These can be placed under debulk endotracheal and/or bronchial tumors to achieve airway direct vision with the use of rigid bronchoscope (Fig. 3) or with the patency [9]. Airway fire is of particular concern in these procedures assistance of a guide wire using fluoroscopic guidance and a flexi- and the risk of fire should always be considered and minimized. ble bronchoscope. 6316 Current Pharmaceutical Design, 2012, Vol. 18, No. 38 Abdelmalak et al.

Endo-bronchial Electrocautery Complete Mediastinal Staging Using EBUS-TBNA This technique is equally effective and less expensive than Nd: EBUS-TBNA has proven to be valuable for mediastinal lymph YAG laser therapy for intraluminal airway obstruction [10, 11]. It is node staging of lung cancer [23] with the ability to sample lesions thought to produce less airway scarring and subepithelial fibrosis even beyond the reach of standard mediastinoscopy. These proce- compared with the use of Nd: YAG laser [12]. Moreover, there are dures can be fairly lengthy as all lymph nodes found to be over also several instruments used with this technique like snares, 5mm in size sampled, working from higher nodal stations (N3) blades, probes and hot forceps to address several technical issues through lower stage nodal stations (N1) during a systematic medi- not fully addressed by simple laser technique. astinal staging procedure.

Bronchoscopic Cryotherapy Electromagnetic Navigational Bronchoscopy (ENB) This procedure is an alternative to using a laser that entails the ENB is designed to enable the operator to biopsy lesions within therapeutic application of extreme cold for local destruction of tis- the periphery of the lung, beyond the reach of the bronchoscope. sue by freezing-induced coagulation necrosis. Nitrous oxide is used This is a catheter-based system used through the working channel as a cryogen by virtue of the cooling of gas on expansion (Joule- of a bronchoscope. It is comprised of the following [9]: Thomson effect).. The technique uses special probes applied via a 1. a sensor probe able to navigate the bronchial tree and commu- flexible bronchoscope. Lacking the risk of fire, tissue perforation or nicate real-time information concerning its position; smoke plume the technique can be used in the presence of high inspired concentrations of oxygen. This technique is also very use- 2. an electromagnetic location board; ful for removing large airway clots, semi-solid foreign bodies or 3. an extended working channel; mucus plugs [13, 14]. There is a new spray cryotherapy technology 4. a computer system that converts CT scans into multiplanar under study but clinical utility and safety have not yet been fully images with 3-D virtual lung reconstruction. addressed with regard to venting high volume gas expansion from The use of such a system will require certain requirements in- the liquid to gas phase of nitrous oxide. cluding specialized non-magnetic procedure (OR) bed, and if Management of Airway Fistulas needed a non-magnetic breathing circuit holder (Fig. 4). This set-up allows navigational guidance within the lungs to endobronchially Diseases like esophageal cancer may develop airway invasion invisible targets beyond the limits that the standard bronchoscope and cause aerodigestive fistulae that may be palliated with either can reach, followed by a tissue biopsy, in a manner similar to single or dual lumen stenting when surgery is not possible [15]. stereotactic brain biopsies. Both moderate (conscious) sedation and Similarly the use of cyanoacrylate glue and similar methods have general anesthesia techniques are used in this setting. been advocated to manage inoperable cases of airway stump dehiscence or bronchopleural fistulae [16] .

Removal of Foreign Bodies

The removal of foreign bodies was one early use of bronchoscopy. This may be accomplished with either a flexible or rigid bronchoscope depending on the nature of the foreign body and the clinical status of the patient. A wide range of tools have been designed for this purpose including wire baskets, forceps and other grasping instruments, endoscopic magnets, cryotherapy probes etc.

Lung Transplant Airway Dehiscence Restoration Airway dehiscence is a potentially fatal complication typically arising in the early postoperative period (days to several months) following lung transplantation [17]. In most cases temporary metallic airway stenting can be used to provide airway support while Fig. (4). A non-metallic breathing circuit holder for use with navigational infection treatment and healing may occur [18, 19]. Long term bronchoscopy (SuperDimension ®). This is used instead of the usual metal management is often an important challenge in these patients. design in order to avoid interference with the electromagnetic imaging system. (Circuit holder design courtesy of Ken Barclay, Cleveland Clinic) Endobronchial Treatment of Inflammatory Airway Diseases Reprinted with permission, Cleveland Clinic Center for Medical Art & Photography © 2011-2012. All rights reserved. Benign airway diseases such as Wegener’s granulomatosis, sarcoidosis, and strictures related to mycobacterial or fungal disease ADVANCED THERAPEUTIC PROCEDURES may be treated with combination of endobronchial steroid injection, Fiducial Implantation cryotherapy, balloon dilation, dilation using a rigid bronchoscope and application of topical mitomycin-c [20]. Stereotactic radiosurgery is a treatment possibility for inoperable lung tumors. Fiducial markers are placed in or near the target ADVANCED DIAGNOSTIC PROCEDURES tumor to facilitate precise tumor ablation. For peripheral lung lesions, ENB may offer an attractive alternative to CT-guided place- Endobronchial Ultrasound-guided Transbronchial Needle As- ment of these fiducials [24] with less risk of pneumothorax. piration (EBUS-TBNA) An EBUS bronchoscope is a flexible bronchoscope containing Pleural Dye Marking both conventional bronchoscopic optics and a linear array ultra- In cases where a small lesion may not be palpable during video sound probe. This combination allows the operator to perform di- assisted thoracotomy (VATS) or thoracotomy, ENB can be used for rected needle aspiration of abnormal mediastinal structures instead guidance to inject a small amount of indigo carmine dye close to of “blind” transbronchial needle aspirations. It is an accurate, safe the target lesion and at the pleural surface as a guide for surgical and cost-effective technique that facilitates the biopsy of mediasti- resection. nal lymph nodes and peribronchial lesions [21, 22].

Anesthesia for Bronchoscopy Current Pharmaceutical Design, 2012, Vol. 18, No. 38 6317

Endoscopic High dose Rate Brachytherapy ANESTHETIC CARE In cases where malignant airway obstruction is recalcitrant to Pre-operative Evaluation maximum dose external beam radiation therapy and where pallia- The extent of preoperative evaluation depends on several con- tive techniques like stenting or laser resection continue to be limited siderations, such as whether the procedure is elective, urgent or by extrinsic compression and tumor in-growth, additional radiation emergent, and how stable or critical the airway is. In elective cases, can be delivered by placing a catheter through which a radiation pre-operative assessment is usually conducted in the customary source may be used to give additional radiation therapy. Broncho- fashion with special attention to the following: scopy is used to precisely place this catheter, which is typically placed under conscious sedation [25]. • The nature and extent of the proposed procedure. • Common associated conditions and co-morbidities: heavy Bronchoscopic Lung Volume Reduction (BLVR) tobacco smoking coronary artery disease and chronic obstruc- This is still an experimental technique, with several variations, tive/restrictive pulmonary disease, chronic alcoholism, malnu- used to treat severe emphysema. The goal is to replace open lung trition and aspiration pneumonitis. volume reduction surgery with its associated morbidity and mortal- • Airway evaluation and review of possible symptoms of airway ity with a minimally invasive option. Technologies like valves, compromise, such as hoarseness, stridor, use of accessory thrombin glue, airway bypass techniques, coils and steam ablation muscles of respiration, dysphagia, or orthopnea. etc. are not yet approved for use in the US but the Spiration IBV • A review of the clinical notes concerning the size of the lesion, system and the PneumRX coils have the CE mark and are currently its location and extent, especially relative to vital structures. A approved for use in treating severe emphysema elsewhere. These computerized tomographic scan of the neck and chest will help patients have end-stage chronic obstructive pulmonary disease and rule out airway abnormalities or mediastinal masses. can present challenges with both oxygenation and ventilation. • A history of type and duration of chemotherapy and its possi- Bronchoscopic Valve Implantation for Persistent Bronchopleu- ble effects on vital organs (especially the heart and lungs). ral Fistula Interventional Pulmonology Procedures and the Difficult Air- In exceptional circumstances air leaks from the lung paren- way chyma may persist following thoracic surgery. In those with an intractable leak, under a human device exemption (HDE) the FDA Patients undergoing bronchoscopic procedures are potentially has approved the use of the Spiration IBV valves to treat prolonged difficult airway cases, although in the majority of these cases the air-leak after thoracic surgery [26]. problem is that of lower airway pathology and so does not impact significantly on intubation. Even in patients with critical tracheal Bronchial Thermoplasty stenosis, ventilation is usually very possible, and intubation is usu- Bronchial thermoplasty is a bronchoscopic procedure in which ally achieved with a small endotracheal tube. controlled heat is applied endobronchially to reduce the mass of the Pre-medication airway smooth muscle as a treatment for severe high-dose inhaled steroid dependent asthma [27]. This procedure is performed over Pre-medication with sedatives and anxiolytics should be con- three bronchoscopic sessions, each session treating different parts sidered only for very anxious patients, because the pulmonary of the lungs. The procedure recently has been FDA approved and status of many bronchoscopy patients is poor, and because some of has been shown to reduce asthma symptoms and trips to ER as well the medications used in these patients may have respiratory depres- as lost days of work [28, 29]. These procedures are done with con- sant effects. Nevertheless, when it is considered necessary to use scious sedation with asthma premedication and several assessments them, judicious care should be exercised, with small titrated doses. of asthma control prior to and after the procedure. Once medicated, these patients should not be left alone without monitoring. As an added safety precaution, supplemental oxygen MODERN BRONCHOSCOPY SUITES should be provided before sedation is administered. Premedication Today's modern bronchoscopy suites (Fig. 5) are sometimes with atropine was once popular to counteract possible bradycardia actually "hybrid" ORs that allow surgeons and pulmonologists to and manage secretions; however the routine use of atropine as a perform combined open, minimally invasive, and image guided premedication is no longer recommended [30]. procedures in the same operative setting. These interdisciplinary, Monitored Anesthesia Care multifunctional rooms employ cutting edge technology with the goal of improving patient outcomes. Monitored anesthesia care is a commonly used technique, especially outside the OR. The majority of uncomplicated and routine diagnostic as well as some simple therapeutic bronchoscopic procedures can be performed under moderate sedation, at least in selected patients undergoing selected procedures. However, in more complex cases, such as when the lung is compromised, or when a pa-

tient becomes unable to tolerate the respiratory depressant effects of many of the commonly used sedatives, ventilation support may become necessary. It should also be noted that because of their detailed understanding of the lung pathology and their special knowledge of the respiratory status of a patient, pulmonologists are able to make very accurate judgments in determining which patient would be a good candidate for moderate (conscious) sedation provided by a sedation nurse while supervised by the pulmonologist, versus those cases requiring deep sedation/monitored anesthesia Fig. (5). Modern bronchoscopy suite with anesthesia machine and auto- care (MAC) or general anesthesia by an anesthesiologist. In the mated record keeping system, along with C-arm, and electromagnetic navi- latter situation, many sedatives have been successfully employed, gation equipment. Photo courtesy of Cleveland Clinic. bronchoscopy Suite. Reprinted with permission, Cleveland Clinic Center for Medical Art & including midazolam, fentanyl, morphine, remifentanil, alfentanil, Photography © 2011-2012. All rights reserved. and propofol. More recently dexmedetomidine and fospropofol have been added to the list of drug options [31-33]. The required 6318 Current Pharmaceutical Design, 2012, Vol. 18, No. 38 Abdelmalak et al. depth and technique of anesthesia to safely facilitate these proce- clinical utility of steroids in this context is controversial. Evidence dures will have implications for the qualifications of the provider; supporting the use of steroids includes its efficacy prior to certain for example, in Ohio sedation nurses are limited to monitoring maxillofacial procedures due to their proven benefit in reducing the moderate (conscious) sedation under the supervision of the pul- degree of postoperative edema and inflammation [36-38]. On the monologist and may not ordinarily be involved in providing deep other hand, Hughes et al have shown that steroids are ineffective in anesthesia. reducing airway edema following carotid endarterectomy [39]. Additionally, steroids are also beneficial as an anti-nausea medica- General Anesthesia tion (vide infra) [40]. Finally, many bronchoscopic surgery patients A total intravenous anesthetic technique (TIVA), typically an with underlying lung conditions (e.g. Wegener’s granulomatosis) infusion of pure propofol administered at between 50 and 150 that require chronic steroid therapy are treated by many clinicians mcg/kg/min, is usually preferred over an inhalational anesthetic with 100 mg of hydrocortisone (the so-called “stress dose” steroids) technique. This is for several reasons. First, it ensures continuous to avoid adrenocortical insufficiency in the face of chronically sup- delivery of anesthesia compared to an inhalation technique where pressed suprarenal gland by the exogenously administered steroid. ventilation leaks occur around the rigid bronchoscope [34], or with However, again the effecacy of this treatment has not been scien- the flexible bronchoscope being inserted into and removed from the tifically demonstrated [41]. airway, or with the insertion of instruments like balloons, forceps, and cautery, or with techniques such as intermittent apnea or jet Anti-nausea Prophylaxis ventilation in addition to the intermittent airway suctioning per- Nausea and vomiting and a likely increased risk of aspiration formed by the pulmonologists for optimal visualization. Secondly, could be detrimental to some bronchoscopy patients because of TIVA avoids pollution of the operating room by inhalational anes- limited pulmonary reserve. Also, since an ETT is used only in a thetic agents. Third, it avoids the risk of exposing operating room limited number of these patients, the majority of the procedures are personnel to anesthetic vapors. Finally, it should be noted that with done with techniques that do not fully protect against aspiration— TIVA, the integrity and functionality of the intravenous line should such as use of a rigid bronchoscope, a SGA or no artificial airway be monitored throughout the procedure. In addition, the Bispectral whatsoever (natural airway). The use of maximum anti-nausea pro- index monitor ( BIS Monitor) ( Covidien, Dublin, Ireland) can be phylaxis, especially in patients with risk factors for complications, used to help monitor the depth of anesthesia and avoid intraopera- is therefore justified. In such cases, the use of propofol TIVA is tive recall [35]. helpful, as is the avoidance of inhalation anesthetics and of nitrous oxide. Dexamethasone in dosages of 4-10 mg IV of commonly used The Utility of Muscle Relaxation [40] as well as other agents. Muscle relaxation facilitates both SGA and ETT insertion. Re- laxation of the jaw muscles makes easier insertion of a rigid laryn- Management of the FiO2 goscope for suspension laryngoscopy, as well as insertion of rigid Administrating 100 % fraction of inspired oxygen (FiO2) in bronchoscopes much easier and safer. Muscle relaxation also im- bronchoscopy procedures is very common. However, it is usually proves overall lung compliance by eliminating the chest wall com- necessary to maintain oxygen concentrations at the lowest tolerable ponent. Finally, by the virtue of providing a motionless patient, it is level, below 40%, during thermal treatment with Nd: YAG lasers as advantageous in situations where unexpected patient movement well as with other procedures where an airway fire could occur. might result in serious consequences. For example, during laser– Periods of extended apnea and complete airway obstruction can be based procedures a motionless patient drastically decreases the risk expected during some especially challenging cases. Complete air- of unwanted misdirection of the laser beam that might result in way occlusion frequently occurs during the critical phase of remov- damage to normal airway tissues, to major vessels or to the esopha- ing the stent or stent fragments or when inflated balloon dilators are gus. A motionless patient will also help increase precision in biop- used for tracheobronchial dilation. Therefore, it is always advisable sying small paratracheal nodes decreasing the number of sampling to return to ventilation with 100% oxygen before extraction of the attempts and shortens the procedure. In cases where a SGA is used stent, prior to exchange of airways, and prior to extubation. Finally, muscle relaxation also helps minimizing trauma to the vocal cords if during thermal treatment patients cannot tolerate lower oxygen caused by the frequent insertion and removal of the bronchoscope levels, it may become necessary to defer treatment temporarily, and against contracted cords—which often happens when muscle relax- ventilate with higher oxygen concentrations and consider using ants are not used. therapy such as debulking via a rigid bronchoscope or via cryoabla- tion, where oxygen concentrations may be maintained at higher Fluid Management in Bronchoscopic Surgery levels. It is prudent to restrict intravenous fluid administration to the minimum volume required, as many have limited lung reserve and AIRWAY MANAGEMENT CHOICES FOR BRONCHO- are at risk of pulmonary congestion or even frank pulmonary SCOPIC PROCEDURES edema, especially if they have concomitant cardiac disease, such as • Natural Airway left-sided or right-sided heart failure, which may have been a com- This is a popular technique, especially when relatively short plication of their long standing lung pathophysiology (cor pulmon- procedures are performed in a remote bronchoscopy suite where an ale). anesthesia machine is unavailable. A moderate (conscious) sedation technique is appealing for these procedures as spontaneous ventila- The use of Corticosteroids in Bronchoscopic Surgery tion can be maintained. Special emphasis should be placed on good Many anesthesiologists and surgeons use corticosteroids, in airway topical anesthesia to allow the patient to tolerate the bron- particular dexamethasone, as a prophylactic measure to decrease choscope without the need for deep planes of sedation and their airway edema after airway surgery. Steroids might be usefult to associated risks. Bronchoscopy may be performed in this setting reduce post-operative vocal cord edema when the flexible fiberoptic either trans-nasally or trans-orally using a bite block or other airway bronchoscope (alone or through an SGA and in the absence of ETT) designed for FOB use. has been inserted into and removed from the airway several times, rubbing against the vocal cords in the process, or alternatively • Endotracheal Tube (ETT) where a rigid bronchoscope has been used for a prolonged duration. When a standard 5.9 mm diagnostic bronchoscope is used, a Steroids are also used in cases where extensive tracheobronchial size 7.5 ETT may be used but when using a 6.7 mm therapeutic tissue trauma has been done during a prolonged procedure. The Anesthesia for Bronchoscopy Current Pharmaceutical Design, 2012, Vol. 18, No. 38 6319 bronchoscope the 8.0 ETT is the smallest preferred tube. Obviously the larger the endotracheal tube the less likely that the bronchoscope will get stuck or that high airway pressures will be an issue. Most commonly size 8.5 or 9.0 mm ID ETT are used for these procedures to allow for enough room around the operating bronchoscope for easy and adequate ventilation. There are several types of bronchoscopy adaptors (Fig. 6) that incorporate diaphragms to reduce the air-leak, although higher gas flows are generally needed to continue to deliver adequate ventilation to compensate for the remaining leak. The ETT can and should be cut short (preferably after intubation, to facilitate navigation of the fiberoptic bronchoscope (Fig. 6). However if there is a significant risk of bleeding it may be advisable to leave the tube long enough to enable potential need for endobronchial intubation and one lung ventilation to isolate a potentially asphyxiating bleed. Intubating patients with a tracheal stent, whether a SEMS stent or a silicone stent, requires special caution, as it risks distorting or dislodging the stent distally that may occlude the airway. A shortened large-bore ETT can be used via an existing tracheotomy using flexible bronchoscopic instruments (Fig. 7). As a Fig. (7). This patient had a remote laryngectomy for cancer, and later devel- general principle, ETT provides a secure airway, which is helpful in oped tracheal stenosis just below the stoma. Later on he also developed patients with severe gastroesophageal reflux disease, hiatal hernia, tumor invasion at the level of the carina. Here we see an 8.0 mm ID en- post esophagectomy with stomach pull through operation, and/or dotracheal tube used as a conduit for the bronchoscope. Only the tip of the tube could be accommodated in the stenotic trachea; the tube cuff func- there is a need to insert the EBUS scope esophageally to obtain tioned as an external seal. This improvised arrangement allowed positive transesophageal biopsies of nodes and lesions that are closer to the pressure ventilation while also allowing for dilation the trachea using the esophagus than the tracheo-bronchial tree (Fig. 8). Of note that ETT flexible bronchoscope. This allowed the use of a small diameter rigid bron- will also provide protection to the vocal cords against repeated choscope to deploy a silicone stent to the carina. Reprinted with permission, trauma and friction with the bronchoscope in long procedures that Cleveland Clinic Center for Medical Art & Photography © 2011-2012. All would require multiple insertions and retractions of the broncho- rights reserved. scope.

Fig. (6). A large diameter endotracheal tube (ETT) is used for a broncho- Fig. (8). An EBUS bronchoscope is inserted esophageally next to an exis- scopic procedure, please note the blue Portex swivel adapter, that facilitates ting ETT for biopsying lesions that are closer to the esophagus than the simultaneous spontaneous ventilation during diagnostic and therapeutic trachea. Reprinted with permission, Cleveland Clinic Center for Medical Art bronchoscopy. Here the ETT was cut short to facilitate decrease resistance & Photography © 2011-2012. All rights reserved. to bronchoscope going in an out of the ETT, as well improve its maneuver- ability. Reprinted with permission, Cleveland Clinic Center for Medical Art 3. For coring out a large tumors invading the tracheo-broncheal & Photography © 2011-2012. All rights reserved. tree,

4. To maintain airway patency in the face of a large mediastinal • Rigid Bronchoscope (Fig. 3) mass causing airway compression. A rigid bronchoscope is preferred for major airway interven- When the rigid bronchoscope is used, ventilation can be tions such as: achieved either by attaching the anesthetic circuit to the broncho- 1. The insertion and removal of silicone stents because of their scope side port for conventional ventilation [42], or via jet ventila- size and their noncompressible material, tion, where the jetting device is attached to the bronchoscope side port through a special adaptor. Leaks around the rigid bronchoscope 2. For removal of large broncholiths and granulation tissue, are common, but are easily remedied by increasing the fresh gas flow, and packing the mouth with saline-soaked gauze. Special 6320 Current Pharmaceutical Design, 2012, Vol. 18, No. 38 Abdelmalak et al. attention should be given to protecting the lips and teeth. In addition care should be taken at the end of the case when removing the gauze so as to avoid subsequent airway obstruction from retained gauze pieces when the bronchoscope is removed.

• Supraglottic Airway In cases where the tracheal lesion is subglottic, a supraglottic airway (SGA) can be used to advantage [43, 44], as it does not enter the glottis (Fig. 9 and Fig. 10A and B). This arrangement allows access to the subglottic lesion by providing a conduit for a flexible bronchoscope, as well as providing a means of ventilation (Fig. 11A and B). However, since it is a less definitive airway, it does not guarantee protection against aspiration. The techniques described above require clear communication between the anesthesiologist and the pulmonologist. Use of a fiberoptic swivel connector adapter will allow continuous ventilation (Fig. 11B), thereby avoiding circuit disconnection during flexible bronchoscopy, in a manner similar to use of an ETT.

• The use of Airway Exchange Catheters in Bronchoscopic Surgery

Airway exchange devices can be useful during bronchoscopic procedures because of the dynamic nature of the procedures that might require different forms of airway during the same procedure and because one may encounter situations in which the airway is expected to be difficult to intubate. Accordingly it is advisable to Fig. (9). Illustration of a balloon dilator being passed through a bronchosco- start with awake intubation, with a relatively small-sized ETT, pref- pe for the treatment of subglottic stenosis. The i-gel SGA as shown above erably a Parker Flex-Tip™ Tracheal Tube. Compared to the stan- allows access to treat subglottic lesions while allowing positive pressure dard tube, use of the Parker tube has reduced from 89% to 29% (P ventilation. Fig. (1) shows how the balloon is inflated. Reprinted with per- < 0.0001) the need to reposition the tube during insertion into the mission, Cleveland Clinic Center for Medical Art & Photography © 2011- trachea [45]. Then an airway exchange catheter can be used to re- 2012. All rights reserved. place it with a larger tube to facilitate the flexible bronchoscopic procedure. If a rigid bronchoscope is required, the exchange cathe- after removing the rigid bronchoscope. An exchange catheter can ter could be used for access to the airway until the laryngeal inlet is also be effective for intubation through an LMA but it is possible visualized through the rigid bronchoscope and the scope is secured that the exchange catheter may slip behind the glottis and result in in position. The same principle can be applied again after finishing esophageal intubation, so standard methods of assessing tube posi- with the rigid bronchoscope; here, the exchange catheter is intro- tion must still be used [46]. duced through the rigid bronchoscope and used to insert an ETT

Fig. (10). Left (A): Illustration showing the use of an EBUS equipped bronchoscope for the ultrasonic imaging of paratracheal nodes via an endotracheal tube. Notice how the presence of the tube limits the region that the EBUS probe can scan and also provides for suboptimal probe alignment. Right(B): These two limitations are overcome by the use of a supraglottic airway – in this case an i-gel. Reprinted with permission, Cleveland Clinic Center for Medical Art & Photography © 2011-2012. All rights reserved. Anesthesia for Bronchoscopy Current Pharmaceutical Design, 2012, Vol. 18, No. 38 6321

POSTOPERATIVE CARE Most of the procedures described above are performed as outpatient procedures, where patients are discharged the same day. However, extremely ill patients with borderline functional may benefit from overnight admission. This compares favorably with invasive thoracic surgery, which requires post-operative ICU admission and a prolonged hospital stay.

MANAGEMENT OF UNIQUE AIRWAY CASES Long Term Management of Post Airway Fire Complications

Survivors of extensive airway fires often present periodically to tertiary and quaternary care facilities for long term management of their complex airway pathology; developed as a result of the airway fire or subsequent complex tracheal repair. Such patients tend to suffer from recurrent tracheal stenosis due to recurring scar build up. When the tracheal lumen becomes significantly narrowed, the symptoms of stridor, shortness of breath and limited functionality capacity require management.

Treatment consists of balloon dilation, electrocautery or laser- ing of the scars with or without mitomycin application. This treatment sequence may require a variety of airway interventions depending on the severity and extent of the stenosis, and stage of the Fig. (12). A tracheal rupture was encountered as a complication of tracheal procedure. The procedure generally begins with bag mask ventila- balloon dilation, and was managed surgically with tracheal graft, and posto- tion, then passage of a supraglottic airway through which an operat- perative ventilation accomplished through the insertion of two microlaryn- ing bronchoscope may be introduced. Some degree of dilatation geal tubes (MLT) with the tube cuff positioned distal to the repaired tear in both right and left bronchi, and the two MLTs were connected together with a standard double lumen tube connector to the breathing circuit. Reprinted with permission, Cleveland Clinic Center for Medical Art & Photography © Uvula 2011-2012. All rights reserved.

is accomplished with balloon dilation, laser cautery, etc. This may be followed by either an the passage of an ETT or rigid bronchoscope by the interventional pulmonologist. In extreme cases where there is very tight continually recurring stenosis of a short tracheal

segment, an ENT or a thoracic surgeon performs an operative tracheal resection and re-anastomosis.

Management of Anterior Mediastinal Mass (AMM)

The presence of an anterior mediastinal mass can predispose

patients to severe respiratory or cardiovascular complications, during anesthesia. These may include airway obstruction, compression Fig. (11A). A well seated i-gel, view from the nasopharynx, used for EBUS of the cardiac chambers, and compression of the pulmonary artery biopsy of high tracheal lymph node. [47].Therefore, particular caution is required in managing these patients.

Spontaneous ventilation has been highly recommended in the anesthetic management of AMM patients, because muscle relaxants are not used and negative intrapleural pressure is maintained [48]. Several conservative anesthetic plans have been proposed for managing AMM [49]. Some propose that the patient should be intu- bated awake after being topicalized and sedated while positioned in the least symptomatic position. The use of dexmedetomidine, a

selective agonist with sedative, analgesic, amnestic [50], and 2 antisialagogue properties [51] has been suggested as having particular utility as a sedative adjunct in this regard. This drug maintains spontaneous respiration with minimal respiratory depression and has been used in the management of AMMs [52]. Patients under dexmedetomidine sedation are generally easy to arouse [53], a property that has been exploited during awake fiberoptic-assisted intubation [31]. However, this advantage, may not hold under Fig. (11B). Many bronchoscopic cases under general anesthesia may be higher doses (off label). An anesthetic induction using inhalational conducted using a supraglottic airway (SGA). Illustrated here is the use of agents while maintaining spontaneous respiration is another poten- an i-gel SGA in conjunction with a (blue) Portex flexible bronchoscope tial course of action. This would seem of particular utility in unco- adapter. Notice the black flexible bronchoscope inserted through the Portex operative patients. adapter. The large SGA lumen and the use of a Portex adapter allows for easy positive pressure ventilation in such a setting, although appropriate Severe cases that include the management of patients with attention to avoid excessive airway pressures is always needed. Reprinted larger AMMs (causing > 50% reduction in airway diameter as seen with permission, Cleveland Clinic Center for Medical Art & Photography © on a computed tomography scan) should not be treated outside of 2011-2012. All rights reserved. the OR. Some authorities recommend that cardiopulmonary bypass 6322 Current Pharmaceutical Design, 2012, Vol. 18, No. 38 Abdelmalak et al. be available on stand-by and that femoral vessel cannulation should 5. When the condition has stabilized, assess the damage with a be secured prior to induction [49, 54]. As a precaution against cata- ventilating rigid bronchoscope; remove any debris and foreign strophic loss of the airway after induction. bodies. 6. Consider the use of IV steroids; however, their efficacy is not Tracheoesophageal Fistulas (TEF) proven. Although tracheoesophageal fistulas (TEF) are best known to 7. Use antibiotics. medical students in the context of congenital anomalies involving the embryology of the trachea and esophagus, more commonly they 8. Implement supportive therapy, including ventilation, and extu- may occur as a result of malignant disease or following radiation bate when clinically indicated. treatment for such disease. 9. Perform tracheotomy if necessary. A malignant tracheoesophageal fistula is a pre terminal condi- Tracheal Rupture tion in esophageal cancer and is associated with significant suffer- Tracheal rupture or loss of tracheal integrity may complicate ing; in particular, regurgitation into the trachea via the fistula is a any of the above-mentioned procedures. However, they occur more continuing concern. The general consensus concerning management frequently with traumatic intubation, tracheostomy, rigid broncho- is to use stents to cover the fistula. scopic dilation, balloon dilation, or complicated metallic stent re- Stent placement is often accomplished under general endotra- moval. Reported risk factors for tracheal rupture include advanced cheal anesthesia. In such cases, the ETT tip should be placed distal age, chronic obstructive pulmonary disease, weakened tracheal to the site of the TEF to avoid blowing gasses into the fistula with walls, (usually secondary to chronic airway inflammation), previous positive pressure ventilation. However, this is not always possible. procedures, infection, and steroid therapy [58-61]. Awake fiberoptic intubation methods usually work best in such a The signs and symptoms of tracheal rupture are non-specific, setting, as well as the maintenance of spontaneous ventilation pre- but a combination of such non-specific symptoms and signs in the vents gas loss through the fistula.. While this can be accomplished clinical setting should lead to a high degree of suspicion. Dyspnea utilizing inhalational anesthetics, concerns include operating room and a dry cough are sometimes the only signs evident in an awake contamination from leaking anesthetic gases with the risk of inade- patient. Cyanosis and tachycardia may also be evident. Other signs quate anesthesia for patients, and contamination of the operating include hemoptysis, persistent air leak, subcutaneous emphysema, room staff with anesthetic agent. An alternative would be very care- pneumomediastinum, and pneumothorax [62-64]. ful titration of intravenously administered anesthetic, like propofol, and/or dexmedetomidine. Bronchoscopy is the gold standard for the diagnosis of tracheal rupture. It is also critical in assessing the extent of the tear. Routine COMPLICATIONS chest radiographs and bronchoscopy are usually sufficient for diag- Potential Complications of Bronchoscopic Procedures nosis in most cases. Potential complications of bronchoscopic procedures are nu- The management of a tracheal tear can be observational (con- merous, and range from hypercarbia , hypoxemia and cough to servative) or surgical (Fig. 12), depending on the extent of the in- major bleeding, loss of airway integrity, endobronchial fire damage, jury, the presenting signs and symptoms, and the general condition pneumothorax formation, and injury to glottic structures. The use of of the patient. In general, small, shallow tears that do not lead to jet ventilation can be complicated by pulmonary barotrauma. Laser severe compromise in ventilation and oxygenation can be treated conservatively [65, 66] If the patient is dependent upon positive air (CO2) cooled or Argon plasma related cerebral or cardiac emboli have been reported as well [55]. Other disease specific risks may pressure-assisted ventilation, however, surgical treatment is needed. include acute carcinoid syndrome and acute bronchospasm. Regardless of the choice of management, the status of the trachea should be monitored with frequently repeated tracheoscopy. High Risk Procedures Ventilatory management consists of adequate oxygenation and Metallic stent removal has a high associated risk of complica- ventilation of the patient, and the prevention of worsening subcuta- tions. Potential complications include retention of stent pieces, neous emphysema, pneumomediastinum, or pneumothorax. This mucosal tears with bleeding, re-obstruction, the need for postopera- can be achieved by positioning the ETT so that the cuff is distal to tive mechanical ventilation pneumothorax, damage to the pulmo- the level of the injury (Fig. 12), and by close monitoring of the nary artery, and death [56]. When the stent is fractured during re- airway pressure, keeping it at the lowest possible level. A higher moval, unwanted fragments may remain permanently embedded in FiO2 and respiratory rate may be required. Selective or bilateral the tissue. In one report, critical airway obstruction occurred during bronchial intubation can be performed in tears located above or removal of a tracheal stent using a rigid bronchoscope under general near the carina. It is important to note that standard direct intubation anesthesia, and cardiopulmonary bypass had to be instituted ur- is potentially hazardous, because a false passage can be easily cre- gently; the stent was eventually removed by directly opening the ated. Fiberoptic-guided intubation may be safer. trachea [57]. Other possible management options include high frequency Airway Fire Associated with Laser Surgery oscillating ventilation or hyperbaric oxygen therapy [67, 68]. In rare One particularly devastating complication is the occurrence of situations, cardiopulmonary bypass or percutaneous cardiopulmon- an airway fire. Management is summarized as follows: ary support systems have been used [69, 70]. Pneumothoraces should be treated with chest tubes, pain should be managed, and Steps to Take in Case of Airway Fire Include hemodynamics should be monitored and supported where needed. 1. Discontinue laser and turn off O2 (as well as N2O if it was mistakenly used.) SUMMARY 2. Remove the burning endotracheal tube and drop it in a bucket Interventional pulmonology is a fast-growing field. These pro- of water. cedures are at times complex, and the patient population is very sick. Many of these surgeries are performed out of the operating 3. Flush area with water or normal saline. rooms. Anesthesiologists need to stay abreast of the advances in 4. Re-intubate immediately and resume ventilation with 100% this field, and of the anesthetic challenges that might come with it. O2. The key to favorable outcomes lies in deep understanding of the underlying lung pathology, open two-way communication between Anesthesia for Bronchoscopy Current Pharmaceutical Design, 2012, Vol. 18, No. 38 6323 the anesthesiologist and pulmonologist, understanding the nature of complications following lung transplantation. Chest 2001 Dec; the procedure, and above all, extreme vigilance and preparedness. 120(6): 1894-9. [18] Fernandez-Bussy S, Akindipe O, Kulkarni V, Swafford W, Baz M, CONFLICT OF INTEREST Jantz MA. Clinical experience with a new removable tracheobronchial stent in the management of airway complications Support was provided solely from institutional and/or depart- after lung transplantation. The Journal of heart and lung mental sources. The authors have no conflicts of interest to declare. transplantation : the official publication of the International Society for Heart Transplantation 2009; 28(7): 683-8. 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Received: June 6, 2012 Accepted: June 28, 2012