Critical Care and TraumaSection Editor: Jukka Takala

Continuous Airway Access for the Difficult Extubation:The Efficacy of the Airway Exchange Catheter

Thomas C. Mort, MD BACKGROUND: The American Society of Anesthesiologists Task Force on the Man-agement of the Difficult Airway regards the concept of an extubation strategy as alogical extension of the intubation process, although the literature does not providea sufficient basis for evaluating the merits of an extubation strategy. Use of anairway exchange catheter (AEC) to maintain access to the airway has been reportedon only a limited basis.METHODS: I reviewed an observational analysis of a prospectively collected difficultairway quality improvement database for patients who were extubated over anAEC for a known or presumed difficult airway primarily in the intensive care unit.The data were reviewed for time to reintubation, number of attempts to reintubatethe trachea, method of securing the airway, incidence of hypoxemia duringreintubation, and complications encountered during reestablishment of the airway.RESULTS: Fifty-one patients with an indwelling AEC failed their extubation trial.Forty-seven of 51 AEC patients were successfully reintubated over the AEC (92%),with 41 of 47 on the first attempt (87%). In three of the four AEC reintubationfailures, the AEC was inadvertently removed from the glottis during the reintuba-tion process, and one patient had significant laryngeal edema precluding endotra-cheal tube advancement.CONCLUSIONS: Maintaining continuous access to the airway postextubation via anAEC can be an important component of an extubation strategy in selected difficultairway patients. The indwelling AEC appears to increase the first-pass success rate inpatients with known or suspected difficult airways and decrease the incidence ofcomplications in patients intolerant of extubation and requiring tracheal reintubation.(Anesth Analg 2007;105:1357–62)

“Airway management” comprises care of the pa-tient during tracheal intubation, maintenance of theendotracheal tube (ETT) in situ, and extubation, withcontinued control of the airway into the postextuba-tion period. The American Society of Anesthesiolo-gists Task Force on the Management of the DifficultAirway regards the concept of an extubation strategyas a logical extension of the intubation process. Cur-rent literature does not provide a sufficient basis forevaluating the merits of an extubation strategy (1), andmost efforts have been expended on addressing strat-egies, safety concerns and techniques for intubatingthe trachea, with relatively little attention paid toextubation. Further, the Closed Claim Analysis fordifficult airway management concluded that the de-velopment of management strategies covering emer-gence and the recovery phase after extubation may

improve patient safety (2). Therefore, maintaining aconduit within the trachea that affords the ability toresecure the airway may serve as the central point of apreformulated extubation strategy (1).

Airway exchange catheters (AEC) have been usedto more safely change ETT as well as to maintainaccess to the airway after extubation, thus allowing areversible extubation if needed (3–6). Successful rein-tubation of the trachea with an AEC for a difficultextubation is not a new concept, yet reports of thispractice have been limited. Three separate groupsreviewed 278 difficult extubation patients, but only 29patients required attempted reintubation over theAEC. Details of the tracheal reintubation were pro-vided in only 4 of the 29 AEC-assisted reintubationattempts, and no complications were reported (6).Published complications related to the AEC have beenmore plentiful than reports touting the AEC’s role inmaintaining access during the clinician’s most difficultairway encounters; hence, the literature offers few detailsregarding its reintubation success on a larger scale(7–13). Extubation intolerance (failure) is relatively un-common in the elective operating room (OR) patient, butthe critically ill intensive care patient suffers extubationfailure regularly (0.4%–25%) (14–24).

Patients with a known or suspected difficult airwayrepresent a patient cohort who may benefit from an

From the *Department of Anesthesiology, Simulation Center, HartfordHospital, Hartford; and †Department of Anesthesiology, University ofConnecticut School of Medicine, Farmington, Connecticut.

Accepted for publication July 17, 2007.There are no conflicts of interest to be disclosed by the author

regarding this manuscript.Address for correspondence and reprint requests to Thomas C.

Mort, MD, Department of Anesthesiology, 80 Seymour St., HartfordHospital, Hartford, CT 06015. Address e-mail to tmort@harthosp.org.

Copyright © 2007 International Anesthesia Research SocietyDOI: 10.1213/01.ane.0000282826.68646.a1

Vol. 105, No. 5, November 2007 1357

extubation strategy involving reversible extubation(14–21). This is the first report to provide details, in arelatively large cohort of difficult airway patients, onthe reintubation first-pass success rate, reasons forreintubation failure, and any complications associatedwith reestablishment of the airway after extubation.Further, this is the first report describing extensive useof both the smaller adult 11F and the medium-sizedadult 14F AEC.

METHODSIn an observational analysis, a difficult airway

quality improvement database was reviewed for pa-tients who were extubated over an AEC for a knownor presumed difficult airway in the OR, the postanes-thesia care unit (PACU), or the intensive care unit(ICU). Data were collected by the author prospectivelyand entered into a Microsoft Excel spreadsheet(1998–2002); then, the database was transferred to andmaintained in an SPSS statistical package data sheet(2002–2006). Patients were cared for directly by theauthor or by members of the anesthesia airway team.If observation of postextubation patients extendedbeyond regular working hours (evening and nightshifts), the author collected and verified data throughICU care team interviews and review of the medicalrecords. The hospital’s IRB waived the need for in-formed consent.

Over a 9-yr period, 354 patients were extubatedwith a Cook AEC (3.7 mm E.D.-11F, 4.7 mm-14F or 6.3mm-19F, Cook Critical Care, Bloomington, IN) left inthe trachea for a potential reversible extubation as partof a staged extubation strategy. The AEC remained inthe trachea until reintubation was considered unlikelyfor each individual patient by the ICU and anesthesiaairway team. Reintubation of the trachea was man-aged by the anesthesia airway team (an anesthesiaattending physician alone or an anesthesia resident[CA-2, CA-3] directly supervised by the attendingstaff) at the patient’s bedside. The anesthesia teammembers’ experiences with reintubation over an in-dwelling AEC varied, although they routinely per-formed tracheal intubation over a bougie airway catheteror tracheal tube exchanges over an AEC.

Patient analysis was performed on the primarygroup, which included patients with an indwellingAEC, who required reintubation within 24 h and asecondary group of patients who had initially had anindwelling AEC in the postextubation period but whothen underwent removal of the AEC based on thepresumed tolerance of the extubated state. Patients inthe secondary group subsequently required reintuba-tion within 7 days of tracheal extubation. These twogroups were reviewed for the time from extubation toreintubation, the number of attempts required toreintubate the trachea (with and without the AEC inplace), the incidence of hypoxemia during reintuba-tion, the method used to resecure the airway, and any

complications encountered during reestablishment ofthe airway. Hypoxemia was defined as a desaturationnadir of Spo2 �90% and severe hypoxemia as Spo2�70%. Reintubation of the patient’s trachea was indi-vidualized for each patient and at the discretion of theICU and anesthesia teams. Typically, shortness ofbreath, tachypnea, worsening oxygen saturations, stri-dor, increased work of breathing, and failure of pul-monary toilet despite therapeutic assistance by thenursing and respiratory therapy staff contributed tothe decision for reintubation.

Data were analyzed using SPSS 12 (SPSS Inc.,Chicago, IL). The contingency �2 test was used forcategorical variables in comparing complications be-tween patients with and without the AEC in place yetrequiring reintubation of the trachea. Statistical sig-nificance was accepted at P � 0.05.

RESULTSIn the review period, 354 patients with a known or

suspected difficult airway, based on previous airwayencounters and current physical examination, hadaccess to their trachea maintained by an indwellingAEC after extubation. Other methods of staged extuba-tion (transition from ETT to laryngeal mask airway[LMA] or bronchoscopic-assisted extubation) were rela-tively few in the ICU setting and were not reviewed.

After extubation over an AEC, each patient re-mained in a monitored environment (the ICU setting,the PACU, or transition from the OR to the PACU).The AEC remained in place for a mean of 3.9 h (range,5 min to 72 h). All patients in the first group whounderwent an AEC-assisted reintubation did sowithin 24 h after extubation. The second group did nothave the AEC in position at the time of their reintu-bation. The AEC size used for the extubation varied:11F (151 patients typically �5�5� tall, 46%), 14F (165patients typically taller than 5�5�, 50%) and 19F (13patients taller than 5�10�, 4%). The location ofthe patient at the time of tracheal extubation includedthe OR (17 postsurgical patients extubated at theconclusion of their anesthesia), the PACU (24 postsur-gical patients extubated after their transfer from theOR to the PACU for postanesthesia recovery), and theICU (288 patients). Most of the ICU patients (75%) hadbeen intubated for �48 h, and many were in therecovery phase of resolving pneumonias, congestiveheart failure, tracheobronchitis, neuro/mental statusalterations, and other maladies placing them at highrisk for potential extubation failure. Seventy-two per-cent of the 354 patients had a known difficult airwaybased on a history of difficult airway managementrequiring multiple conventional attempts (�3) or re-quiring an accessory airway device to secure theairway in the emergency room, the OR, or a remotelocation intubation during the current hospitalization.The remaining patients, 28%, had a suspected difficultairway based on their current physical examination

1358 Extubation of the Difficult Airway ANESTHESIA & ANALGESIA

(airway-related swelling; edema or tissue trauma sec-ondary to surgery, infection or injury; intravascularvolume resuscitation; systemic response to sepsis;drug reaction or patient positioning, e.g., prone).Restriction in cervical range of motion or limitedaccess to the airway due to injury, hard cervical collar,a halovest or bandages/dressings were additionalfactors suggestive of potential difficult airway man-agement. Fifty-one patients had an indwelling AEC atthe time of the reintubation procedure.

Forty-seven of 51 AEC patients had successfulAEC-assisted reintubation (92%, Table 1), with 41 of 47on the first attempt and thus an 87% first-pass successrate. Five patients required two attempts to pass theETT via the AEC, and one patient required threeattempts (each with a smaller diameter ETT). Of thefour AEC failures, three patients had the AEC inad-vertently removed during the reintubation process,and in the fourth patient the ETT could not be passedover the AEC despite progressive ETT downsizing,lubrication, and counterclockwise rotation of the ETT(marked laryngeal edema noted by fiberoptic bron-choscopy during reintubation). Reintubation of thesefour patients included the Fastrach LMA™ in twopatients, fiberoptic bronchoscopy in one patient, andconventional laryngoscopy in one patient who re-quired four attempts. Seven patients suffered hypox-emia, with mild desaturation (Spo2 �90%, n � 3) orsevere desaturation (Spo2 �70%, n � 4), during thereintubation process. Three of the 4 patients whodeveloped severe hypoxemia were the AEC failures,and each experienced bradycardia (�40 bpm) andconcomitant hypotension during the reintubation pro-cess. Only two patients who underwent successfulAEC-assisted reintubation experienced severe reduc-tion of the heart rate while resecuring the airway (onehypoxemia induced).

All reintubations were performed by an attendinganesthesiologist alone (n � 23) or by an anesthesiologyresident under direct supervision of an attendinganesthesiologist (n � 28). The attending alone andattending/resident groups had similar reintubationsuccess rates via the indwelling AEC. Three cases ofinadvertent AEC migration out of the trachea duringthe reintubation process occurred: two cases handled

by the resident/attending and one handled by theattending physician alone. The relatively low failurerate did not allow statistical analysis to identify anydifferences between resident and attending staff.

Forty-one percent of the AEC-assisted reintubationsin 51 patients occurred within 2 h of the initialextubation, representing an overall rate of 6% (21 of354 patients). The remaining 30 extubation failureswith an indwelling AEC occurred beyond 2 h postex-tubation, primarily between 2 and 10 h. Once thedecision to reintubate the trachea was made, admin-istration of oxygen was provided by bag-mask venti-lation in the majority of patients (44 of 51) by theanesthesia airway team, with the AEC lateralized tothe corner of the mouth to optimize the mask seal. Theremaining seven patients had 3–6 L of oxygen flowprovided directly via the AEC, in lieu of bag-masksupport. Direct administration of oxygen via the AECeffectively kept the seven patients’ oxygen saturation�90% in each case, but this method required a briefdisconnection of oxygen flow during the initial pass-ing of the ETT over the indwelling AEC. High-pressure jet ventilation via the AEC was not used inany of the cases.

Patient preparation for AEC-assisted reintubationincluded no medication or local anesthesia appliedtopically to the upper airway (27%). The remainingpatients received light-to-moderate doses of sedative-hypnotic drugs: midazolam 0.01–0.02 mg/kg, 1–3 mgtotal (12% of patients), etomidate: 0.07–0.17 mg/kg,4–14 mg total (34%), or propofol �0.4 to 1.4 mg/kg,30–130 mg total (27%). Reintubation of the tracheawas facilitated with laryngoscopy to open the orohy-popharynx in three-quarters of the patients. The re-maining patients underwent manual jaw thrust/lingual retraction to assist with ETT passage over theAEC. Only two patients received neuromuscularblocking drugs to assist in the intubation procedureover the AEC; in the remaining patients, spontaneousventilation was maintained.

Thirty-six patients (second group) required reintu-bation after their AEC had been removed. Eighteen ofthese 36 patients (50%) were intolerant of extubationwithin 120 min, 4 patients between 2 and 4 h, and 14patients succumbed to reintubation beyond 4 h. Thesepatients proved worthy of their designation as “known

Table 2. Reintubation Technique in Patients Without an AirwayExchange Catheter (AEC)a (n � 40)

Direct laryngoscopy alone 3 (3� attempts)LMA/Fastrach LMA� 20Flexible fiberoptic bronchoscope 6Rigid fiberscope (Bullard®, Shikani®) 4Tracheal tube introducer (bougie) 3Surgical airwayb 4a Includes failed AEC intubation attempts, AEC migration (36 patients without AEC � 4 failedAEC cases).b These four patients had successful ventilation/oxygenation achieved via bag-mask (1 case),laryngeal mask airway (LMA) (2 cases) and the esophagotracheal Combitube® (1 case) butcould not be intubated via the glottis.

Table 1. Success Rate of Reintubation with AEC In Situ

Overall success rate 92% (47 of 51 patients)1st attempt 87% (41 of 47 patients)2nd attempt 11% (5 of 47 patients, requiring

downsizing of ETT)3rd attempt 1 case (required downsizing of ETT)4th attempt 1 case-failed despite progressive

downsizing of ETT, FastrachLMA® rescue

AEC migration outof airway

6% (3 cases) rescued with flexiblefiberscope-1 case, multipleattempts-1 case, Fastrach LMA�-1case

AEC � airway exchange catheter; ETT � endotracheal tube; LMA � laryngeal mask airway.

Vol. 105, No. 5, November 2007 © 2007 International Anesthesia Research Society 1359

or suspected difficult airway,” since the vast majorityrequired multiple attempts to resecure the airway(three or more attempts with laryngoscopy plus theaccessory device/technique, 77%) when comparedwith only one patient with the indwelling AEC whorequired three attempts. Table 2 illustrates the conven-tional and accessory airway devices that were re-quired to assist the practitioner in resecuring thepatients’ airways.

The 14% first-pass reintubation success rate (firstattempt with direct laryngoscopy or accessory device)in the non-AEC group was dwarfed by the AEC-assisted first-pass success rate of 87% (Table 3). Nearlyall (90%) of the non-AEC group required an accessoryairway device or an advanced technique to success-fully reestablish the airway (Table 3). Of note, afterfailure to intubate the trachea in four patients, despiteconcerted attempts with accessory devices, a surgicalairway was required. Two of these four patientsreceived bag-mask ventilation during the establish-ment of the surgical airway, and two patients hadconcurrent and successful ventilation and oxygen-ation via an LMA during placement of the surgicalairway.

Oxygen desaturation in the non-AEC group wascommon during the reintubation process, with thenadir of �90% Spo2 occurring in 50% of the patients;40% of these suffered severe hypoxemia (Spo2 �70%,Table 3). Esophageal intubation was more common inthe non-AEC group (18% to 0%), as was hypoxemia-driven bradycardia with profound hemodynamicdeterioration. Table 3 compares the various complica-tions of the reintubation procedure between thosereintubated with and without an indwelling AEC.

DISCUSSIONIn the high-risk extubation patient with known or

suspected airway management difficulties, develop-ment of a strategy to maintain access to the airway andto offer the safety of reversibility if the extubated stateis not tolerated should be considered (1). This strategywill depend, in part, on the surgical and medicalconditions of the patient, on the previous airwayprocedures and current airway status, as well as on

the skills and preferences of the practitioner (1). Rein-tubation of the trachea in the known or suspecteddifficult airway patient appears fraught with compli-cations, as illustrated in this study by the group ofpatients who underwent extubation of their tracheaover an AEC, had it subsequently removed when thereintubation risk was presumed to be low, yet latersuffered extubation intolerance and were reintubated.

Postextubation hypoventilation, airway compro-mise, ventilation-perfusion inequalities, and obstruc-tion due to fatigue may afflict the patient in the OR, inthe PACU, and in particular in the ICU (3,4). Continu-ous access to the airway can be maintained via an AECwith the proximal tip secured to the patient’s clothingor forehead (waterproof adhesive tape). This is welltolerated by most patients (90%) and thus is a valuableoption, considering a reintubation rate that variesfrom 0.4% to 25% in the various PACU and ICUpopulations (3–7,14–21).

Currently, there are no evidence-based guidelinesregarding the optimal period of time for maintainingairway access postextubation via an indwelling AEC.Experts have suggested at least 30–60 min or until thelikelihood of reintubation is minimized (3,5,6,22–24).Unfortunately, our database suggests that a minimumof 30–60 min would underestimate the need for areversible extubation in a significant number of thesehigh-risk patients. Moreover, the potential for changesin the patient’s clinical status makes it difficult topredict when the need for reintubation is minimized.This may be particularly true in the ICU population,who may suffer acute alterations in their cardiopul-monary, metabolic, or neurological status, or othercritical medical/surgical issues that may influencetheir tolerance of extubation.

If the intolerance of the extubated state is basedprincipally on the presence or potential accumulationof periglottic edema, then the patient may benefit fromextending the duration of the indwelling AEC to60–120 min. Periglottic edema contributing to airwaycompromise often occurs immediately upon extuba-tion or within 10–45 min of extubation, although ithas been noted that symptomatic laryngeal edemamay develop as late as 8 h postextubation (14,15).

Table 3. Complications of the Reintubation Procedure

AEC present(n � 51)

AEC absent(n � 36) P

First-pass success rate for reintubation 87% 14% (5) �0.02Hypoxemia during reintubation (Spo2 �90%) 8%b (4) 50% (18) �0.01Severe hypoxemia during reintubation (Spo2 �70%) 6%a(3) 19% (7) 0.05Bradycardia (heart rate �40) with hypotension 4% (2) 14% (5) �0.05Multiple intubation attempts (�3) including the

placement of an accessory airway device10%b (5) 77% (28) �0.02

Esophageal intubation 0 18% (6)Rescue airway device/technique 6%a (3) 90% (32) �0.01a Includes the AEC failures due to inability to pass ETT into trachea (1 case) and proximal migration of the AEC out of the trachea (3 cases).AEC � airway exchange catheter; ETT � endotracheal tube.

1360 Extubation of the Difficult Airway ANESTHESIA & ANALGESIA

Extending the duration of continuous airway accesswould seem prudent if the patient demonstrates car-diopulmonary pathology and other systemic illness.Difficult airway patients who have failed an extuba-tion trial are typically handled by determining theprevious extubation time and then extending it by afactor of two- to three-fold to provide a reasonablecushion for maintaining access in the event of failure.If mental or neurological status is compromised, espe-cially when coupled with cardiopulmonary limita-tions, then extending the time to 12–24 h or beyondmay provide a valuable safeguard.

Even if the time devoted to maintenance of airwayaccess is extended, patients may still fail their extubationtrial well after removal of the AEC. Clearly, guidelines toassist the practitioner in decision-making are needed,and further study to investigate the optimal duration ofthe indwelling AEC appears warranted.

Previous investigators who incorporated an airwaycatheter (3.7–4 mm ED) found it was well tolerated,affording reasonable comfort and allowing the pa-tients to retain the ability to phonate and generate asecretion-clearing cough (3,6). The current database,again, reconfirms that the 11F (3.7 mm ED) is welltolerated in over 90% of patients and may serve a keyrole in resecuring an airway in the difficult extubationpatient. Moreover, the two larger sized AEC, the 14F(4.7 mm ED) and the 19F (6.3 mm ED), which had notbeen previously reported for the difficult extubationpatient, were useful for maintaining access to theairway and reintubating the trachea for a reversibleextubation in this study. In this database, the larger14F AEC, based on patient interviews postextubation,had a relatively minor rate of patient discomfort (8%),similar to that of the smaller 11F AEC (7%). The largestsized AEC (19F), although an excellent conduit forreintubation or exchanging an ETT, had a significantlyhigher rate of patient discomfort (50%). Its use formaintaining a reversible extubation has been curtailedat the author’s institution due to this higher rate ofdiscomfort and patient dissatisfaction. Although AEC-assisted reintubation of the trachea is not guaranteed,the 92% success rate of both sizes of AEC is excep-tional and compares favorably with the three previ-ously published studies reporting AEC-assistedreintubation (27 of 29 attempts successful, 93%) (3,4,6).

The presence of the AEC to assist in reintubatingthe trachea is a major step toward improving safety inthe difficult airway patient. This is well illustrated bya comparison of the complication rates of AEC-assisted reintubations and tracheal extubations indifficult airway patients who had had their AECremoved before their declaration of extubation intol-erance (Tables 2 and 3). Despite this high success ratefor AEC-assisted reintubation, the practitioner and theairway team must be prepared for the possibility thatthe patient may fail the extubation trial and requireemergent or urgent intubation of the trachea by a

means other than the AEC. Immediate access to con-ventional and advanced airway rescue devices and thepresence of competent and experienced airwaypersonnel capable of providing advanced airwaymanagement in this difficult airway population areimperative (25–32).

The limitations of this data analysis are that it wasneither a randomized nor a blinded evaluation ofAEC-assisted extubation of the difficult airway pa-tient, nor did it compare one method of maintainingairway access to another. Removal of the indwellingAEC was based on the clinical determination that therisk of reintubation was diminished; thus, it waslimited by the practitioner’s individual experience andjudgment and the unpredictable nature of the patient’sclinical status. Some patients may have remainedinstrumented with the AEC longer than needed,whereas others may have prematurely lost the benefitof continuous airway access.

The optimal duration of continuous access to theairway after extubation in this patient population wasnot directly tested. Beyond conjecture and the author’sexperienced opinion, this data analysis provided non-definitive evidence-based findings to assist the practi-tioner in answering this important question.

In summary, this practice analysis reconfirms thatthe AEC is an efficient method of maintaining con-tinuous access to the airway after extubation, as it iswell tolerated and potentially offers a clinically valu-able conduit for reintubation, as reported by earlier,more limited reviews (3,4,6). Further, in the tallerpatient, the medium-sized AEC (14F, 4.7 mm ED) maybe a useful alternative to the smaller adult version(11F, 3.7 mm ED), as both sizes appear to be welltolerated by most patients. Complications of resecur-ing the airway in the known or suspected difficultairway are relatively common, especially when con-tinuous airway access is not preserved. The optimaltime for maintaining access to the airway postextuba-tion should be addressed in further studies.

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1362 Extubation of the Difficult Airway ANESTHESIA & ANALGESIA