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Home , Air embolism, Embolism

Journal of Clinical Medicine

Review Air : Practical Tips for Prevention and Treatment

Colin J. McCarthy 1, Sasan Behravesh 2, Sailendra G. Naidu 2 and Rahmi Oklu 2,*

1 Massachusetts General Hospital, Harvard Medical School, Division of Interventional Radiology, 55 Fruit Street, GRB-290A, Boston, MA 02114, USA; [email protected] 2 Mayo Clinic Arizona, Division of Vascular & Interventional Radiology, Phoenix, AZ 85054, USA; [email protected] (S.B.); [email protected] (S.G.N.) * Correspondence: [email protected]; Tel.: +1-480-342-1650

Academic Editor: Bernhard Rauch Received: 18 September 2016; Accepted: 27 October 2016; Published: 31 October 2016

Abstract: is a rarely encountered but much dreaded of surgical procedures that can cause serious harm, including death. Cases that involve the use of endovascular techniques have a higher risk of air embolism; therefore, a heightened awareness of this complication is warranted. In particular, central venous and arterial catheters that are often placed and removed in most hospitals by a variety of medical practitioners are at especially high risk for air embolism. With appropriate precautions and techniques it can be preventable. This article reviews the causes of air embolism, clinical management and prevention techniques.

Keywords: Air embolism; endovascular; ;

1. Introduction An intravascular air embolism (VAE) is a rare, preventable, but serious complication of endovascular procedures resulting in significant morbidity and mortality. It occurs as a result of a gradient that allows air to enter the stream, which can subsequently occlude blood flow. This complication can arise in a range of clinical situations including interventional radiology (IR) procedures, trauma, , central line placement and removal, and certain types of surgical interventions such as cardiac and neurosurgery. The main causes of systemic and cerebral air embolism are shifting from the traditional culprits of open surgery and trauma to endoscopy, , biopsy, and peripheral venous access [1,2]. While the true incidence of air embolism is unknown, as many instances go unreported, one study included a series of over 11,000 placements and found an incidence of 1 in 772 [3]. As a result of its high chance of mortality and morbidity, physicians should be well equipped to prevent, identify, and manage air embolism. In this article, we explore the clinical presentation of air embolism, review practical tips for prevention and treatment, and present cases of iatrogenic air embolism.

2. Etiology of Air Embolism Air emboli exist only when there is a connection between air and the vascular system. A pressure gradient is required to drive air into the vascular system; a central line or its tract (post-removal) is an example of such a connection. Often these lines terminate in the superior vena cava where low central venous pressure (CVP) below further increases the likelihood of an air embolism. A venous air embolism occurs when air enters the venous system and eventually causes an obstruction in the . The gradient between external atmospheric pressure and the intravascular low central venous pressure (CVP) is especially increased by hypovolemia or during inspiration by creating a negative intrathoracic pressure which enhances the possibility of

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J.during Clin. Med. inspiration2016, 5, 93 by creating a negative intrathoracic pressure which enhances the possibility 2of of air 13 entry. As CVP may be sub‐atmospheric at baseline in up to 40% of patients [4], those patients in an upright position or those undergoing IR procedures such as catheter placements are airparticularly entry. As susceptible. CVP may be sub-atmospheric at baseline in up to 40% of patients [4], those patients in an uprightIn contrast, position arterial or those air embolism undergoing occurs IR procedures following such direct as instillation hemodialysis of catheterair into the placements arterial tree are particularly(i.e., angiography) susceptible. or paradoxically, through a septal defect or patent (PFO). Though the higherIn contrast, intravascular arterial pressure air embolism in the occurs arterial following system is direct somewhat instillation protective, of air arterial into the air arterial embolism tree (i.e.,has the angiography) potential to or produce paradoxically, through or a septal in any defect organ or patent with limited foramen collateral ovale (PFO). blood Though supply, theeven higher when intravascular the volume of pressure air is small. in the arterial system is somewhat protective, arterial air embolism has theThe potential consequences to produce of intravascular ischemia or air infarction entrainment in any are organ determined with limited by volume, collateral rate, blood and supply, route even(venous when or thearterial). volume Animal of air studies is small. have been performed to estimate the volume of air required to produceThe lethal consequences circulatory of intravasculararrest, with case air entrainmentreports suggesting are determined the lethal by dose volume, of air rate,in adults and routeto be (venousbetween or200 arterial). and 300 Animal cc, or 3–5 studies mL/kg have [1,5,6]. been Though performed this to appears estimate to thebe volumea large amount of air required of air not to produceeasily introduced lethal circulatory to the vascular arrest, with system, case it reports has been suggesting shown that the lethala 14‐gauge dose ofneedle air in can adults transmit to be between100 cc of 200air andper 300second cc, orwith 3–5 a mL/kg pressure [1, 5gradient,6]. Though of 5 this cm appears H20. In toaddition, be a large a 15 amount French of (5 air mm not easilydiameter) introduced peel‐away to the sheath vascular used system, during it placement has been shown of a tunneled that a 14-gauge hemodialysis needle cancatheter transmit can 100allow cc of300 air cc perof air second to enter with the a vascular pressure system gradient in just of 5 0.5 cm s H[4].20. When In addition, a large bolus a 15 French of air lodges (5 mm in diameter) the right peel-awayventricular sheath outflow used tract during (RVOT), placement this can of result a tunneled in pulmonary hemodialysis catheter followed can allow by 300 circulatory cc of air tocollapse. enter the vascular system in just 0.5 s [4]. When a large bolus of air lodges in the right ventricular outflowThe tract cardiovascular, (RVOT), this pulmonary can result in and pulmonary neurologic hypertension systems can followed suffer by serious circulatory adverse collapse. effects, particularlyThe cardiovascular, when air enters pulmonary at a high and rate, neurologic which can systemsplace a strain can suffer on the serious right adverse by raising effects, particularlypulmonary whenartery airpressure. enters atLarger a high air rate, bubbles which canare placealso more a strain likely on the to rightcause heart hemodynamic by raising pulmonarydisturbance than pressure.smaller air Larger bubbles air bubbles [7]. With are alsothe morepotential likely for to causeair embolism hemodynamic to occur disturbance almost thaninstantaneously, smaller air bubblesit is prudent [7]. Withfor physicians the potential to take for appropriate air embolism measures to occur for almost prevention. instantaneously, It should italso is prudentbe noted forthat physicians low volume to air take entering appropriate the venous measures system for can prevention. often times It shoulddissipate also and be that noted air thatemboli low can volume therefore air enteringspontaneously the venous resolve system on their can own often with times minimal dissipate sequelae, and that (see air Figures emboli 1 and can therefore2). However, spontaneously an arterial resolve embolism on their may own be withimmediately minimal sequelae,lethal. A (seecase Figures of air 1embolism and2). However, is often andifficult arterial to embolismdiagnose (Figure may be 3) immediately and oftentimes, lethal. the A cause case of of air an embolismair embolism is often cannot difficult be unequivocally to diagnose (Figuredetermined.3) and This oftentimes, is not unusual the cause since of an cerebral air embolism air embolism cannot is be thought unequivocally to be uncommon. determined. Due This to is a notcombination unusual sinceof low cerebral overall airincidence embolism and is some thought cases to where be uncommon. the diagnosis Due goes to a undiagnosed combination of[2], low an overallanesthesiologist incidence or and intensive some cases care where specialist the diagnosismay see goesonly undiagnoseda few or none [2 ],during an anesthesiologist their career. orA intensivecommon error care specialist is for the mayair embolism see only ato few be misdiagnosed or none during as their a thrombotic career. A commonor thrombo error‐embolic is for thestroke air embolism[8]. to be misdiagnosed as a thrombotic or thrombo-embolic [8].

(a) (b)

Figure 1. Cont.

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(c) (d) (c) (d) FigureFigure 1. 1.A A 35-year-old 35‐year‐old man man waswas transferredtransferred from an an outside outside hospital hospital with with altered altered mental mental status status following the placement of a peripheral intravenous line. A CT of the was performed in the followingFigure the1. A placement 35‐year‐old of man a peripheral was transferred intravenous from an line. outside A CT hospital of the with brain altered was performed mental status in the emergency room. Axial (a) and coronal (b) CT revealed a moderate amount of air in the cavernous emergencyfollowing room. the placement Axial (a) of and a peripheral coronal (b intravenous) CT revealed line. a A moderate CT of the amount brain was of airperformed in the cavernous in the sinuses bilaterally (arrows) as well as multiple small foci of air in the region of the pterygoid venous sinusesemergency bilaterally room. (arrows) Axial (a as) and well coronal as multiple (b) CT small revealed foci a of moderate air in the amount region of of air the in pterygoid the cavernous venous plexusessinuses (bilaterallyc), scattered (arrows) in the assoft well tissues as multiple and in thesmall extradural foci of air space in the at region the level of the of pterygoidthe upper venouscervical plexuses (c), scattered in the soft tissues and in the extradural space at the level of the upper cervical spineplexuses (arrowheads). (c), scattered A followin the ‐softup tissuesCT (d) andwas inperformed the extradural the next space day, at the which level revealed of the upper resolution cervical of spine (arrowheads). A follow-up CT (d) was performed the next day, which revealed resolution of the thespine previously (arrowheads). seen air. A Infollow this ‐case,up CT the (d patient) was performed made a full the recovery. next day, which revealed resolution of previously seen air. In this case, the patient made a full recovery. the previously seen air. In this case, the patient made a full recovery.

(a(a) ) ((bb))

FigureFigure 2. 2. A A 61 61‐year‐year‐old‐old male male underwent underwent anan initialinitial femoralfemoral angiogram ((aa),), whichwhich revealedrevealed a a small small Figure 2. A 61-year-old male underwent an initial femoral angiogram (a), which revealed a small amountamount of of air air in in the the tubing tubing of of the the side side port port (arrowhead)(arrowhead) that had traveledtraveled intointo the the superficial superficial femoral femoral amount of air in the tubing of the side port (arrowhead) that had traveled into the superficial femoral arteryartery (arrows). (arrows). As As the the lower lower extremityextremity arteriogramarteriogram (b) revealed nono visiblevisible distaldistal emboli,emboli, it it was was artery (arrows). As the lower extremity arteriogram (b) revealed no visible distal emboli, it was presumedpresumed the the air air was was resorbed. resorbed. There There were were nono adverseadverse sequelae. presumed the air was resorbed. There were no adverse sequelae.

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(a) (b)

(c)

Figure 3. A 69 69-year-old‐year‐old man who was critically ill with sepsis, pneumonia, and Cerebral Vascular Accident (CVA). Immediately after his pulmonary arterial line was pulled, he developed sudden cardiopulmonary arrest, suspected to be related toto airair embolism.embolism. A A post post-mortem‐mortem CT ( a–c) was performed 18 h later, revealing intravascular air in the ascending aorta (a, arrow), (b, arrowhead), right ( c, *) and the liver (arrow). Given the the extent of air, it was considered most likely that the air was related to post post-mortem‐mortem state. Despite these findings, findings, even when the heart was opened under water at autopsy, no air escaped, highlighting the difficulty difficulty in diagnosis of air embolism in some cases.

3. Clinical Clinical Presentation Presentation Following Following Air Air Embolus Symptoms and signssigns associatedassociated with with serious serious air air embolism embolism are are non-specific non‐specific and and can can be be difficult difficult to todiagnose. diagnose. Clinical Clinical symptoms symptoms include include dyspnea, dyspnea, continuous continuous coughing coughing and and chest chest pain.pain. Neurological symptoms includeinclude , seizures, loss of consciousness,loss of consciousness, altered mental status,altered and hemiparesis/hemiplegia.mental status, and hemiparesis/hemiplegia.In many cases, patients may In many exhibit cases, sudden patients onset may of a exhibit combination sudden of onset signs andof a combination symptoms (Figure of signs4). Althoughand symptoms much (Figure of the literature 4). Although discusses much arterial of the infarctsliterature as discusses a result of arterial air embolism, infarcts it as is a worth result noting of air embolism,that intravascular it is worth air cannoting also that cause intravascular venous infarcts air can [9]. also cause venous infarcts [9]. In patients under , reduced end‐tidal CO2 may be noted as the earliest indicator of air In patients under anesthesia, reduced end-tidal CO2 may be noted as the earliest indicator of embolus.air embolus. Importantly, Importantly, reduced reduced oxygen saturation saturation on on pulse pulse oximetry oximetry is is considered considered a a late late sign sign of vascular air embolism [[1].1].

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(a) (b)

(c) (d)

(e) (f)

Figure 4. Cont.

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(g)

Figure 4. Following the placement of right internal jugular tunneled Hickman line, a 76‐year‐old man Figure 4. Following the placement of right internal jugular tunneled Hickman line, a 76-year-old developed an episode of desaturation, tachycardia, and non‐responsiveness. Subsequently, an man developed an episode of desaturation, tachycardia,(g) and non-responsiveness. Subsequently, an immediate CT of brain, neck and chest was performed and was found in the left cavernous sinus immediateFigure(a,b) and CT4. Followingwithin of brain, a left the neck parietal placement and sulcus chest of right was(c); it internal performed was felt jugular to represent and tunneled gas wasair Hickman in found a vessel, in line, thepossibly a left76‐year cavernous a pial‐old .man sinus (a,b)developedThere and within was alsoan a leftepisodea large parietal amount of desaturation, sulcus of air (surroundingc); it tachycardia, was felt the to right representand internalnon‐responsiveness. air jugular in a vessel,vein ( dSubsequently,); possibly with a partially a pial an vein. Thereimmediatevisualized was also centralCT a large of brain, venous amount neck catheter and of air chest (*). surrounding A was brain performed MRI the was rightand performed gas internal was showing found jugular in FLAIR the vein left hyperintensity (cavernousd); with asinus partially in visualized(multiplea,b) and central withinregions venous a (lefte) parietalwith catheter evidence sulcus (*). A (cof brain); itrestricted was MRI felt was todiffusion represent performed ( fair); andin showing a vessel,corresponding FLAIR possibly hyperintensity alow pial signal vein. in multipleThere(arrowheads) regions was also (e on) a with largethe apparent evidence amount diffusionof of air restricted surrounding coefficient the (ADC) right (f); andimagesinternal corresponding ( gjugular). The patientvein low (d );received signalwith a (arrowheads)partially a single on thevisualizedtreatment apparent ofcentral hyperbaric diffusion venous coefficientoxygen catheter but (*). died (ADC) A brain 8 days images MRI later. was (g performed). The patient showing received FLAIR a hyperintensity single treatment in of multiple regions (e) with evidence of restricted diffusion (f); and corresponding low signal hyperbaric oxygen but died 8 days later. (arrowheads)Electrocardiogram on the apparent(EKG) tracings diffusion in coefficient the presence (ADC) of images air embolism (g). The patientmay show received tachycardia, a single ST segmenttreatment changes, of hyperbaric or evidence oxygen of butright died heart 8 days strain. later. Transesophageal can detect Electrocardiogramvery small volumes of (EKG) air, although tracings its in usefulness the presence is operator of air‐dependent embolism [10]. may Arterial show blood tachycardia, gas ST segmentanalysisElectrocardiogram changes, will show or hypoxemia evidence (EKG) andtracings of right hypercarbia in heart the presence strain. most commonly Transesophageal of air embolism [11]. In addition,may echocardiography show small tachycardia, amounts can ST of detect verysegmentair small may volumes be changes, seen relatively of or air, evidence although frequently of right its on usefulnessheartCT scans strain. of the isTransesophageal operator-dependent chest, where a smallechocardiography volume [10]. of Arterial air canmay detect bloodenter gas analysisverya peripheral will small show volumes vein hypoxemia at a ofrelatively air, although and slow hypercarbia rate. its usefulnessSuch findings most is commonly operator have been‐dependent noted [11]. Inin up addition,[10]. to 23%Arterial of small patients, blood amounts gasare of air mayanalysisfrequently be seen will asymptomatic, relatively show hypoxemia frequently and canand occur onhypercarbia CT with scans peripheral most of the commonly chest, IV lines where [11]. as shown In a smalladdition, in volumethe smallcase described ofamounts air may ofin enter air may be seen relatively frequently on CT scans of the chest, where a small volume of air may enter a peripheralFigure 5 vein[12,13]. at In a relatively these cases, slow small rate. amounts Such of findings air travel have to the been pulmonary noted in vasculature up to 23% and of patients,are aresorbed peripheral without vein atsequelae. a relatively slow rate. Such findings have been noted in up to 23% of patients, are are frequentlyfrequently asymptomatic,asymptomatic, and and can can occur occur with with peripheral peripheral IV lines IV lines as shown as shown in the incase the described case described in in FigureFigure5[ 512 [12,13].,13]. In In these these cases,cases, smallsmall amounts amounts of of air air travel travel to tothe the pulmonary pulmonary vasculature vasculature and are and are resorbedresorbed without without sequelae. sequelae.

Figure 5. A 35‐year‐old woman had an incidental finding of air in the right ventricle on non‐contrast CT abdomen performed for renal stone evaluation. The patient was asymptomatic and an IV line had been placed approximately 1 hour earlier. Figure 5. A 35‐year‐old woman had an incidental finding of air in the right ventricle on non‐contrast Figure 5. A 35-year-old woman had an incidental finding of air in the right ventricle on non-contrast CT abdomen performed for renal stone evaluation. The patient was asymptomatic and an IV line had CT abdomen performed for renal stone evaluation. The patient was asymptomatic and an IV line had been placed approximately 1 hour earlier. been placed approximately 1 hour earlier.

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J. Clin. Med. 2016, 5, 93 7 of 13 Although small volumes of air in the venous system may be asymptomatic, this does not hold Although small volumes of air in the venous system may be asymptomatic, this does not hold true for the arterial system, where even small amounts of air can result in end-organ damage. In those true for the arterial system, where even small amounts of air can result in end‐organ damage. In patientsthose with patients a PFO, with there a PFO, is the there potential is the potential for air to for travel air to from travel the from right the heartright heart to the to leftthe left heart, heart, allowing venousallowing air to produce venous air a paradoxical to produce a embolism, paradoxical which embolism, can cause which serious can cause cerebrovascular serious cerebrovascular complications (Figurecomplications6). (Figure 6).

FigureFigure 6. Clinical 6. Clinical illustration illustration of anof an arterial arterial air air embolismembolism in in a apatient patient with with patent patent foramen foramen ovale (PFO) ovale (PFO) can becan seen be in seen the in following the following example example in in which which a a 57-year-old57‐year‐old female female underwent underwent liver liver resection. resection. At the At the end of the case, the patient became profoundly hypotensive, and an air embolism was suspected. end of the case, the patient became profoundly hypotensive, and an air embolism was suspected. Approximately 20 cc of air was aspirated from an indwelling central venous catheter, an ApproximatelyExtracorporeal 20 cc membrane of air was oxygenation aspirated from (ECMO) an indwellingwas initiated central and the venous patient was catheter, transferred an Extracorporeal to ICU membranewhere oxygenation CT brain was (ECMO) performed. was An initiated axial CT andshows the multiple patient areas was of transferred low attenuation to ICU representing where CT brain was performed.infarction of An the axialright (arrow) CT shows and left multiple (arrowhead) areas cerebral of low hemispheres, attenuation consistent representing with underlying infarction of the right (arrow)embolic and source left of (arrowhead) infarct. Furthermore, cerebral the hemispheres, CT shows loss consistent of gray‐white with underlyingdifferentiation embolic consistent source of infarct.with Furthermore, cerebral . the CTTransesophageal shows loss of echocardiography gray-white differentiation was performed consistent (not shown), with revealing cerebral a edema. Transesophageallarge amount echocardiography of air bubbles in wasthe right performed and left (not chambers shown), heart revealing chambers. a large This, amount together of with air bubblesa patent foramen ovale, resulted in . in the right and left chambers heart chambers. This, together with a patent foramen ovale, resulted in paradoxical4. Practical embolism. Tips to Reduce the Risk of Air Embolus

4. Practical4.1. Placing Tips and to Removing Reduce theCentral Risk Venous of Air Catheters Embolus When placing catheters, the CVP should be raised (to decrease the pressure gradient) by placing 4.1. Placingthe patient and Removing in the Trendelenburg Central Venous position. Catheters It should also be ensured that patients are adequately Whenhydrated placing to prevent catheters, hypovolemia the CVP and should to increase be raised CVP. (to Avoiding decrease placement the pressure of venous gradient) catheters by placing the patientduring in inspiration the Trendelenburg when negative position. intra‐thoracic It should pressure also is at be its ensured maximum that is also patients recommended. are adequately Physicians are also advised to take precautions to avoid a short subcutaneous path to the hydrated to prevent hypovolemia and to increase CVP. Avoiding placement of venous catheters during jugular vein, whenever possible. This method decreases the risk of air embolism during catheter inspirationremoval when [14]. negative When there intra-thoracic is no guide wire pressure in place, is the at itsoperator maximum should is occlude also recommended. the needle hub with Physicianstheir thumb. are All also catheter advised lumens to take should precautions be flushed to before avoid placement a short subcutaneous and catheter hubs path should to the be jugular vein, wheneverplaced on possible.tightly. It Thisis also method recommended decreases that the physicians risk of air have embolism a working during knowledge catheter of removal valve [14]. When theremechanisms is no guideand reliability wire in when place, using the a operator peel‐away should sheath, occlude use Luer–lock the needle connections hub with for IV their ports thumb. All catheterand self lumens‐sealing should valves, beand flushed that these before skills placementare maintained and by catheter clinical staff. hubs should be placed on tightly. When removing catheters, it is also recommended to raise CVP by keeping the patient in a It is also recommended that physicians have a working knowledge of valve mechanisms and reliability supine position or with their head down or Trendelenburg position. Ideally, the venotomy site when usingshould a be peel-away below the sheath, level of use the Luer–lock heart to ensure connections adequate for central IV ports venous and pressure self-sealing at the valves, time of and that these skills are maintained by clinical staff. When removing catheters, it is also recommended to raise CVP by keeping the patient in a supine position or with their head down or Trendelenburg position. Ideally, the venotomy site should be below the level of the heart to ensure adequate central venous pressure at the time of removal. Patients should be instructed to perform a during catheter removal, if possible. If this is not J. Clin. Med. 2016, 5, 93 8 of 13

J. Clin. Med. 2016, 5, 93 8 of 13 possible, removing the catheter during active expiration is recommended [14,15]. It should be ensured that theremoval. exit site Patients is covered should be with instructed impermeable to perform dressing a Valsalva and maneuver that pressure during is catheter applied removal, afterward if for 5–10possible. min, for hemostasisIf this is not and possible, prevention removing of the catheter entry. during It is recommended active expiration that is the recommended patient remains [14,15]. It should be ensured that the exit site is covered with impermeable dressing and that supine for 30 min after central venous access removal [15]. pressure is applied afterward for 5–10 min, for and prevention of bubble entry. It is 4.2. Duringrecommended an Angiogram that the or patient Other remains Invasive supine Procedure for 30 min after central venous access removal [15]. When4.2. During conducting an Angiogram invasive or Other procedures Invasive includingProcedure arteriography, it is important to identify high-risk cases in advance.When conducting Use of invasive a continuous procedures flush including through arteriography, a closed system it is is important encouraged. to identify Any wire shouldhigh be‐risk withdrawn cases in advance. from the Use catheter of a continuous gradually, flush while through using a closed a system to is maintain encouraged. a water Any seal and incorporatingwire should be withdrawn the use of from a double the catheter flush. gradually, In addition, while physicians using a syringe should to maintain prepare a water in batches.seal Thisand incorporating avoids having the to use draw of a and double then flush. inject In and addition, thus allows physicians micro-bubbles should prepare to settle. syringes All in tubing shouldbatches. be primed This avoids with having andto draw no airand shouldthen inject be presentand thus inallows syringes micro used‐bubbles for to hand settle. injections. All The syringetubing should should be be primed held upright with saline in order and no to ensureair should that be any present air will in syringes travel towards used for the hand syringe injections. The syringe should be held upright in order to ensure that any air will travel towards the plunger, away from the catheter (Figure7). To further ensure that no air is introduced into the syringe plunger, away from the catheter (Figure 7). To further ensure that no air is introduced into catheter, it is recommended that the syringe be connected from wet to wet end. Additionally, it is the catheter, it is recommended that the syringe be connected from wet to wet end. Additionally, it is recommendedrecommended that that the the complete complete volume volume of of thethe syringesyringe never never be be completely completely injected. injected. It should It should be be ensuredensured that balloonsthat balloons for angioplasty for angioplasty are correctlyare correctly primed primed and and free free of air. of Air-in-lineair. Air‐in‐line detection detection devices incorporateddevices incorporated into modern into infusion modern pumpsinfusion arepumps particularly are particularly useful useful to detect to detect air bubblesair bubbles in in plastic tubingplastic [16]. tubing In surgical [16]. proceduresIn surgical procedures where there where is a highthere risk is a ofhigh air risk embolism, of air embolism, precordial precordial Doppler may be usedDoppler during may anesthesia be used during to allow anesthesia for early to allow detection for early of air detection embolism. of air embolism.

FigureFigure 7. By 7. ensuring By ensuring the the syringe syringe is heldis held with with the the plunger plunger uprightupright ( A),), there there is is a a significant significant decrease decrease in the riskin the of inadvertentrisk of inadvertent injection of any of any air thatair that may may be be contained contained within within thethe syringe (B (B).).

Percutaneous computed tomography‐guided biopsy is another radiologic procedure that Percutaneousis associated with computed a risk of air tomography-guided embolism. This is a rare lung complication, biopsy is another estimated radiologic to occur in procedure less than that is associatedone in every with thousand a risk of airprocedures embolism. [17]. This Small is aamounts rare complication, of air that enter estimated the pulmonary to occur venous in less than one insystem every have thousand the potential procedures to embolize [17]. Small to the amounts coronary ofarteries, air that resulting enter the in ischemia pulmonary and/or venous cardiac system havearrest. the potential Air may to enter embolize the circulation to the coronary by a number , of resulting methods, in including ischemia direct and/or entry cardiac into a arrest. Air maypulmonary enter the vein circulation during needle by a positioning number of and methods, removal including of the stylet. direct Air entry may also into enter a pulmonary by direct vein duringpuncture needle of positioning a pulmonary and arterial removal branch, of theor by stylet. puncture Air of may an alsoair‐filled enter structure by direct adjacent puncture to a of a pulmonaryvessel, creating arterial a branch, fistula. In or some by puncture cases, the exact of an cause air-filled of air structure embolism adjacentmay be difficult to a vessel, to ascertain, creating a particularly when patients are undergoing invasive procedures, as it may not always be apparent fistula. In some cases, the exact cause of air embolism may be difficult to ascertain, particularly when whether the air entered the operative field or from a supporting intravenous line. patients are undergoing invasive procedures, as it may not always be apparent whether the air entered the operative field or from a supporting intravenous line. J. Clin. Med. 2016, 5, 93 9 of 13

5. Air Embolism Management J. Clin. Med. 2016, 5, 93 9 of 13

5.1. Initial Management Techniques 5. Air Embolism Management When there is clinical suspicion of air embolism, a number of initial steps should be taken 5.1.quickly Initial to Managementmanage the Techniquessituation. The initial priority is to prevent further air embolism; if air is noted entering the arterial system, the flush should be stopped immediately and the rotating hemostatic valveWhen (RHV) there should is clinical be fully suspicion opened. of The air embolism,arterial pressure a number should of initial be allowed steps should to passively be taken push quickly the toair manage back out. the This situation. can be Theenhanced initial priorityby turning is to the prevent system further vertically, air embolism; which will if aircause is noted air bubbles entering to therise. arterial In the system, event of the venous flush should air embolism, be stopped the immediately system should and the be rotating dropped hemostatic to minimize valve further (RHV) shouldentrainment be fully of air. opened. The arterial pressure should be allowed to passively push the air back out. This canIn the be enhancedcase of an by unresponsive turning the system patient, vertically, the first which priority will is cause to address air bubbles airway, to rise. In the event and ofcirculation venous air (ABC), embolism, including the system cardiopulmonary should be dropped to minimize (CPR) when further necessary. entrainment Additional of air. staff shouldIn be the called case ofto anhelp, unresponsive either in the patient, form a “rapid the first response” priority isteam to address or as per airway, local protocols. breathing Once and circulationthe patient (ABC), has been including stabilized, cardiopulmonary only then should resuscitation additional (CPR) evaluation when necessary. and management Additional staff be shouldundertaken. be called to help, either in the form a “rapid response” team or as per local protocols. Once the patientOnce has stabilized, been stabilized, the patient only then should should be additional examined evaluation (including and neurological management examination) be undertaken. and 100%Once oxygen stabilized, treatment the patient administered should be examinedby a non (including‐ neurological mask to examination)maximize end and‐organ 100% oxygenoxygenation. treatment If the administered patient is intubated, by a non-rebreather the Fi02 should mask be to set maximize to 100% end-organ(Figure 8). oxygenation. High flow oxygen If the patientmay also is aid intubated, the reabsorption the Fi02 shouldof nitrogen be set gas to from 100% the (Figure bubble8). into High the flow blood, oxygen reducing may the also size aid of the the reabsorptionair embolus [12]. of nitrogen gas from the bubble into the blood, reducing the size of the air embolus [12].

(a) (b)

Figure 8. AA 27 27-year-old‐year‐old woman woman with with encephalitis encephalitis who who suffered suffered a respiratory a respiratory arrest. arrest. Two images Two images from fromaxial CT axial brain CT brain(a,b) performed (a,b) performed shortly shortly afterward afterward revealed revealed extensive, extensive, serpiginous serpiginous hypodensity hypodensity in the insulcal the sulcaldistribution distribution overlying overlying the thecerebral cerebral hemispheres hemispheres bilaterally bilaterally (arrowheads), (arrowheads), representing intravascular air embolization.embolization. The The patient patient made made a a full full recovery recovery with prompt 100% oxygen administration and supportive measures alone.alone.

In cases of venous air embolism, Durant’s maneuver is performed [18,19], by placing the patient In cases of venous air embolism, Durant’s maneuver is performed [18,19], by placing the patient in the left lateral decubitus and Trendelenburg position. This serves to encourage the air bubble to in the left lateral decubitus and Trendelenburg position. This serves to encourage the air bubble to move out of the right ventricular outflow tract (RVOT) and into the right , thereby relieving move out of the right ventricular outflow tract (RVOT) and into the right atrium, thereby relieving the the “air‐lock” effect responsible for potentially catastrophic cardiopulmonary collapse. It is “air-lock” effect responsible for potentially catastrophic cardiopulmonary collapse. It is important to important to note that, in the case of arterial air embolism, patients should be kept in the flat supine note that, in the case of arterial air embolism, patients should be kept in the flat supine position as the position as the head‐down position may worsen cerebral edema [20]. head-down position may worsen cerebral edema [20]. If clinically indicated, commencement of cardiopulmonary resuscitation is warranted. This will If clinically indicated, commencement of cardiopulmonary resuscitation is warranted. This will continue end‐organ and may promote migration of the air embolus into the smaller continue end-organ perfusion and may promote migration of the air embolus into the smaller pulmonary vessels [21]. Of note, cardiopulmonary resuscitation can be challenging if the patient is pulmonary vessels [21]. Of note, cardiopulmonary resuscitation can be challenging if the patient is positioned decubitus, or if there are femoral access catheters and sheaths for example. Patients should J. Clin. Med. 2016, 5, 93 10 of 13 positioned decubitus, or if there are femoral access catheters and sheaths for example. Patients beshould transferred be transferred to an Intensive to an CareIntensive Unit forCare careful Unit monitoringfor careful andmonitoring management, and management, and consideration and shouldconsideration be given should to hyperbaric be given oxygen to hyperbaric therapy, or otheroxygen advanced therapy, treatments or other including advanced Extracorporeal treatments Membraneincluding Extracorporeal Oxygenation (ECMO).Membrane The Oxygenation case in Figure (ECMO).9 demonstrates The case in the Figure usefulness 9 demonstrates of quick and the efficientusefulness initial of quick management and efficient of air initial embolism. management of air embolism.

(a) (b)

(c) (d)

Figure 9.9.A A 68-year-old 68‐year‐old woman woman underwent underwent cerebral cerebral angiogram angiogram (a) for ( evaluationa) for evaluation of 3 cm leftof cavernous3 cm left internalcavernous carotid internal artery carotid artery (*).aneurysm Post procedure, (*). Post procedure, she developed she transientdeveloped aphasia, transient right aphasia, facial droop,right facial and rightdroop, arm and brachyplegia right arm brachyplegia likely secondary likely to secondary air embolism. to air This embolism. was presumed This was to presumed be related to faultybe related occlusion to faulty balloon. occlusion The balloon. patient The was patient immediately was immediately placed in a placed cervical in collara cervical to minimize collar to headminimize movements head movements and distal airand embolization distal air embolization as well as started as well on as 100% started oxygen on 100% therapy. oxygen Hyperbaric therapy. chamberHyperbaric therapy chamber was discussedtherapy was but discussed declined due but to declined concerns due about to patientconcerns movement about patient during movement transport. CTduring angiogram transport. (b,c CT) was angiogram performed (b,c immediately.) was performed Post-procedure immediately. revealed Post‐ airprocedure within therevealed large leftair cavernouswithin the segmentlarge left internal cavernous carotid segment artery internal aneurysm carotid (arrow). artery A CTaneurysm performed (arrow). 2 days A laterCT performed (d) showed 2 thedays embolism later (d) showed had resolved the embolism and this patienthad resolved made aand full this recovery. patient made a full recovery.

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5.2.5.2. Advanced Advanced Management Management AdvancedAdvanced hemodynamic hemodynamic support support and and monitoring monitoring requires requires thethe inputinput of an anesthesiologist or or rapidrapid response response team, team, who who can can perform perform advanced advanced physiological physiological monitoring monitoring and support support such such as as the the useuse of pressors of pressors and and mechanical mechanical ventilation. ventilation.

5.3.5.3. Air Air Aspiration Aspiration In theIn the event event of an of “airan “air lock” lock” in thein the RVOT, RVOT, aspiration aspiration may may be be required. required. This This procedure procedure tends tends to to be difficult,be difficult, perhaps perhaps related related to the narrowto the narrow luminal luminal diameter, diameter, but offers but offers the highest the highest chance chance of success of success when therewhen is already there is a already catheter a catheter near the near right the atrium right atrium or ventricle. or ventricle. In a case In a report,case report, Garg Garg et al. et outlineal. outline the usethe of cardiac use of catheterizationcardiac catheterization to treat anto airtreat embolism an air embolism in the RVOT in the for aRVOT 2-year-old for a with2‐year Tetralogy‐old with of FallotTetralogy [22]. They of Fallot use a 6[22]. French They angiographic use a 6 French Berman angiographic catheter toBerman successfully catheter aspirate to successfully the air pocket aspirate and encouragethe air thepocket use and of catheter encourage aspiration the use “in of thecatheter setting aspiration of “in the and setting cardiovascular of hypotension collapse”. and Typically,cardiovascular 15–20 cc ofcollapse”. air may Typically, be aspirated 15–20 using cc of this air technique. may be aspirated A multi using side hole this catheter,technique. such A multi as the Bunegin-Albinside hole catheter, catheter such (Cook as the Medical, Bunegin Bloomington,‐Albin catheter IN, (Cook USA) Medical, has also beenBloomington, described IN, [1 ,USA)23,24 ].has also been described [1,23,24]. 6. Hyperbaric 6. Hyperbaric Oxygen Therapy Hyperbaric oxygen therapy (HBOT) is the administration of 100% oxygen to patients at a pressure greater thanHyperbaric sea level oxygen and is indicated therapy (HBOT) in the presence is the administration of neurologic deficits. of 100% HBOT oxygen constricts to patients pathologic at a air bubbles,pressure providesgreater than oxygen sea tolevel ischemic and is organs,indicated and in abets the presence the conversion of neurologic of nitrogen deficits. from HBOT gas to constricts pathologic air bubbles, provides oxygen to ischemic organs, and abets the conversion of liquid phase, thereby reducing air bubble size; in essence, it diminishes gas volume, cerebral edema nitrogen from gas to liquid phase, thereby reducing air bubble size; in essence, it diminishes gas and enhances of dissolved oxygen in the blood. It is widely regarded as the gold volume, cerebral edema and enhances partial pressure of dissolved oxygen in the blood. It is widely standard for treatment [25,26]. A study by Blanc et al. found that when HBOT was administered within regarded as the gold standard for treatment [25,26]. A study by Blanc et al. found that when HBOT 6 h, patients had the best outcomes [27], however treatment within 30 h may still be advantageous [28]. was administered within 6 h, patients had the best outcomes [27], however treatment within 30 h Themay successful still be useadvantageous of HBOT is [28]. outlined The successful in Figure use 10. of HBOT is outlined in Figure 10.

(a) (b)

(c) (d)

Figure 10. Cont.

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(e) (f) (g)

Figure 10. The successful use of a hyperbaric oxygen therapy (HBOT) is outlined in this case, in Figure 10. The successful use of a hyperbaric oxygen therapy (HBOT) is outlined in this case, in which which a 69‐year‐old female with a history of suspected lung underwent a CT‐guided lung a 69-year-old female with a history of suspected lung cancer underwent a CT-guided lung biopsy biopsy at an outside facility (a). During the procedure, the patient suffered a cardiorespiratory arrest. at an outside facility (a). During the procedure, the patient suffered a cardiorespiratory arrest. An immediate CT (b) revealed a right (arrow), together with air in the right An immediate CT (b) revealed a right pneumothorax (arrow), together with air in the right pulmonary pulmonary vein (arrowhead). Additional images from the CT scan (c,d), revealed air in the right vein (arrowhead). Additional images from the CT scan (c,d), revealed air in the right coronary coronary artery (black arrow), the ascending thoracic aorta (white arrow) and the epidural artery(arrowhead). (black arrow), The patient the ascending was initially thoracic unresponsive aorta (white and arrow)required and cardiopulmonary the epidural veins resuscitation. (arrowhead). A Thenon patient‐contrast was CT initially brain unresponsive(e) was performed, and required revealing cardiopulmonary air scattered in resuscitation.the vessels overlying A non-contrast the right CT braincerebral (e) was hemisphere performed, (arrowheads). revealing air Subsequent scattered in MRI the of vessels the brain overlying confirmed the right multiple cerebral areas hemisphere of acute (arrowheads).infarction in Subsequentthe right cerebral MRI ofand the cerebellar brain confirmed hemispheres. multiple Axial areas T2 (f of) and acute DWI infarction (g) images in the of the right cerebralbrain anddemonstrated cerebellar hemispheres.acute areas of Axial infarction T2 (f )in and the DWI right (g )cerebellum. images of the The brain patient demonstrated required ICU acute areasmanagement of infarction and in HBOT. the right cerebellum. The patient required ICU management and HBOT.

7.7. Conclusions Conclusions AirAir embolism embolism is is rare rare but but can can be be fatal fatal andand cancan occur during during a a number number of of invasive invasive procedures, procedures, thusthus it isit importantis important that that physicians physicians are are prepared prepared toto deal with with this this complication. complication. Systematic Systematic planning, planning, promptprompt recognition, recognition, and and focused focused treatment treatment offeroffer thethe best chance of of survival. survival. Even Even with with appropriate appropriate treatment,treatment, recent recent figures figures suggest suggest that that the the overall overall one-yearone‐year mortality mortality may may be be in in the the region region of of21% 21% [29]. [29 ]. Radiologists and other physicians alike, should maintain a high degree of suspicion for air emboli Radiologists and other physicians alike, should maintain a high degree of suspicion for air emboli and and consider advanced management, including hyperbaric oxygen therapy, at an early stage. consider advanced management, including hyperbaric oxygen therapy, at an early stage. Acknowledgments: R.O. acknowledges funding from the National Institutes of Health (EB021148) and Acknowledgments:additional supportR.O. from acknowledges Mayo Clinic. funding from the National Institutes of Health (EB021148) and additional support from Mayo Clinic. Author Contributions: R.O. and C.M. conceived and designed the study; C.M., S.B. wrote the manuscript; R.O., AuthorS.N. edited Contributions: the manuscript;R.O. all and authors C.M. approved conceived the and final designed version of the the study; manuscript. C.M., S.B. wrote the manuscript; R.O., S.N. edited the manuscript; all authors approved the final version of the manuscript. Conflicts of Interest: The authors declared no conflicts of interest and have no financial disclosures. Conflicts of Interest: The authors declared no conflicts of interest and have no financial disclosures. References References 1. Mirski, M.A.; Lele, A.V.; Fitzsimmons, L.; Toung, T.J. Diagnosis and treatment of vascular air embolism. 1. Mirski, M.A.; Lele, A.V.; Fitzsimmons, L.; Toung, T.J. Diagnosis and treatment of vascular air embolism. Anesthesiology 2007, 106, 164–177. Anesthesiology 2007, 106, 164–177. [CrossRef][PubMed] 2. Muth, C.M.; Shank, E.S. Gas embolism. N. Engl. J. Med. 2000, 342, 476–482. N. Engl. J. Med. 342 2. 3. Muth,Vesely, C.M.; T.M. Shank, Air embolism E.S. Gas embolism.during insertion of central venous2000, catheters., 476–482. J. Vasc. [CrossRef Int. Radiol.][PubMed 2001, 12] , 1291– 3. Vesely,1295. T.M. Air embolism during insertion of central venous catheters. J. Vasc. Int. Radiol. 2001, 12, 4. 1291–1295.Wysoki, [M.G.;CrossRef Covey,] A.; Pollak, J.; Rosenblatt, M.; Aruny, J.; Denbow, N. Evaluation of various 4. Wysoki,maneuvers M.G.; for Covey, prevention A.; Pollak, of air J.; embolism Rosenblatt, during M.; Aruny, central J.; venous Denbow, catheter N. Evaluation placement. of J. various Vasc. Int. maneuvers Radiol. for2001 prevention, 12, 764–766. of air embolism during central venous catheter placement. J. Vasc. Int. Radiol. 2001, 12, 5. 764–766.Toung, [ CrossRefT.J.; Rossberg,] M.I.; Hutchins, G.M. Volume of air in a lethal venous air embolism. Anesthesiology 5. Toung,2001, T.J.;94, 360–361. Rossberg, M.I.; Hutchins, G.M. Volume of air in a lethal venous air embolism. Anesthesiology 6. 2001Martland,, 94, 360–361. H. Air [CrossRef embolism:][PubMed Fatal air] embolism due to powder insufflators used in gynecological 6. Martland,treatments. H. Air Am. embolism: J. Surg. 1945 Fatal, 68, air 164–169. embolism due to powder insufflators used in gynecological treatments. Am. J. Surg. 1945, 68, 164–169. [CrossRef]

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