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CRITICAL CARE AND TRAUMA

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

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

	Abstract

Top Abstract Introduction METHODS RESULTS DISCUSSION REFERENCES

 
BACKGROUND: The American Society of Anesthesiologists Task Force on the Management of the Difficult Airway regards the concept of an extubation strategy as a logical extension of the intubation process, although the literature does not provide a sufficient basis for evaluating the merits of an extubation strategy. Use of an airway exchange catheter (AEC) to maintain access to the airway has been reported on only a limited basis.

METHODS: I reviewed an observational analysis of a prospectively collected difficult airway quality improvement database for patients who were extubated over an AEC 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 reintubate the trachea, method of securing the airway, incidence of hypoxemia during reintubation, 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 reintubation failures, the AEC was inadvertently removed from the glottis during the reintubation process, and one patient had significant laryngeal edema precluding endotracheal tube advancement.

CONCLUSIONS: Maintaining continuous access to the airway postextubation via an AEC can be an important component of an extubation strategy in selected difficult airway patients. The indwelling AEC appears to increase the first-pass success rate in patients with known or suspected difficult airways and decrease the incidence of complications in patients intolerant of extubation and requiring tracheal reintubation.

	Introduction

Top Abstract Introduction METHODS RESULTS DISCUSSION REFERENCES

 
"Airway management" comprises care of the patient during tracheal intubation, maintenance of the endotracheal tube (ETT) in situ, and extubation, with continued control of the airway into the postextubation period. The American Society of Anesthesiologists Task Force on the Management of the Difficult Airway regards the concept of an extubation strategy as a logical extension of the intubation process. Current literature does not provide a sufficient basis for evaluating the merits of an extubation strategy (1), and most efforts have been expended on addressing strategies, safety concerns and techniques for intubating the trachea, with relatively little attention paid to extubation. Further, the Closed Claim Analysis for difficult airway management concluded that the development of management strategies covering emergence and the recovery phase after extubation may improve patient safety (2). Therefore, maintaining a conduit within the trachea that affords the ability to resecure the airway may serve as the central point of a preformulated extubation strategy (1).

Airway exchange catheters (AEC) have been used to more safely change ETT as well as to maintain access to the airway after extubation, thus allowing a reversible extubation if needed (3–6). Successful reintubation of the trachea with an AEC for a difficult extubation is not a new concept, yet reports of this practice have been limited. Three separate groups reviewed 278 difficult extubation patients, but only 29 patients required attempted reintubation over the AEC. Details of the tracheal reintubation were provided in only 4 of the 29 AEC-assisted reintubation attempts, and no complications were reported (6). Published complications related to the AEC have been more plentiful than reports touting the AEC's role in maintaining access during the clinician's most difficult airway encounters; hence, the literature offers few details regarding its reintubation success on a larger scale (7–13). Extubation intolerance (failure) is relatively uncommon in the elective operating room (OR) patient, but the critically ill intensive care patient suffers extubation failure regularly (0.4%–25%) (14–24).

Patients with a known or suspected difficult airway represent a patient cohort who may benefit from an extubation strategy involving reversible extubation (14–21). This is the first report to provide details, in a relatively large cohort of difficult airway patients, on the reintubation first-pass success rate, reasons for reintubation failure, and any complications associated with reestablishment of the airway after extubation. Further, this is the first report describing extensive use of both the smaller adult 11F and the medium-sized adult 14F AEC.

	METHODS

Top Abstract Introduction METHODS RESULTS DISCUSSION REFERENCES

 
In an observational analysis, a difficult airway quality improvement database was reviewed for patients who were extubated over an AEC for a known or presumed difficult airway in the OR, the postanesthesia care unit (PACU), or the intensive care unit (ICU). Data were collected by the author prospectively and entered into a Microsoft Excel spreadsheet (1998–2002); then, the database was transferred to and maintained in an SPSS statistical package data sheet (2002–2006). Patients were cared for directly by the author or by members of the anesthesia airway team. If observation of postextubation patients extended beyond regular working hours (evening and night shifts), the author collected and verified data through ICU care team interviews and review of the medical records. The hospital's IRB waived the need for informed consent.

Over a 9-yr period, 354 patients were extubated with a Cook AEC (3.7 mm E.D.-11F, 4.7 mm-14F or 6.3 mm-19F, Cook Critical Care, Bloomington, IN) left in the trachea for a potential reversible extubation as part of a staged extubation strategy. The AEC remained in the trachea until reintubation was considered unlikely for each individual patient by the ICU and anesthesia airway team. Reintubation of the trachea was managed by the anesthesia airway team (an anesthesia attending physician alone or an anesthesia resident [CA-2, CA-3] directly supervised by the attending staff) at the patient's bedside. The anesthesia team members' experiences with reintubation over an indwelling AEC varied, although they routinely performed tracheal intubation over a bougie airway catheter or tracheal tube exchanges over an AEC.

Patient analysis was performed on the primary group, which included patients with an indwelling AEC, who required reintubation within 24 h and a secondary group of patients who had initially had an indwelling AEC in the postextubation period but who then underwent removal of the AEC based on the presumed tolerance of the extubated state. Patients in the secondary group subsequently required reintubation within 7 days of tracheal extubation. These two groups were reviewed for the time from extubation to reintubation, the number of attempts required to reintubate the trachea (with and without the AEC in place), the incidence of hypoxemia during reintubation, the method used to resecure the airway, and any complications encountered during reestablishment of the airway. Hypoxemia was defined as a desaturation nadir of Spo₂ <90% and severe hypoxemia as Spo₂ <70%. Reintubation of the patient's trachea was individualized for each patient and at the discretion of the ICU and anesthesia teams. Typically, shortness of breath, tachypnea, worsening oxygen saturations, stridor, increased work of breathing, and failure of pulmonary toilet despite therapeutic assistance by the nursing and respiratory therapy staff contributed to the decision for reintubation.

Data were analyzed using SPSS 12 (SPSS Inc., Chicago, IL). The contingency ² test was used for categorical variables in comparing complications between patients with and without the AEC in place yet requiring reintubation of the trachea. Statistical significance was accepted at P < 0.05.

	RESULTS

Top Abstract Introduction METHODS RESULTS DISCUSSION REFERENCES

 
In the review period, 354 patients with a known or suspected difficult airway, based on previous airway encounters and current physical examination, had access to their trachea maintained by an indwelling AEC after extubation. Other methods of staged extubation (transition from ETT to laryngeal mask airway [LMA] or bronchoscopic-assisted extubation) were relatively few in the ICU setting and were not reviewed.

After extubation over an AEC, each patient remained 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 who underwent an AEC-assisted reintubation did so within 24 h after extubation. The second group did not have the AEC in position at the time of their reintubation. The AEC size used for the extubation varied: 11F (151 patients typically <5'5'' tall, 46%), 14F (165 patients typically taller than 5'5'', 50%) and 19F (13 patients taller than 5'10'', 4%). The location of the patient at the time of tracheal extubation included the OR (17 postsurgical patients extubated at the conclusion of their anesthesia), the PACU (24 postsurgical patients extubated after their transfer from the OR to the PACU for postanesthesia recovery), and the ICU (288 patients). Most of the ICU patients (75%) had been intubated for >48 h, and many were in the recovery phase of resolving pneumonias, congestive heart failure, tracheobronchitis, neuro/mental status alterations, and other maladies placing them at high risk for potential extubation failure. Seventy-two percent of the 354 patients had a known difficult airway based on a history of difficult airway management requiring multiple conventional attempts (3) or requiring an accessory airway device to secure the airway in the emergency room, the OR, or a remote location intubation during the current hospitalization. The remaining patients, 28%, had a suspected difficult airway based on their current physical examination (airway-related swelling; edema or tissue trauma secondary to surgery, infection or injury; intravascular volume resuscitation; systemic response to sepsis; drug reaction or patient positioning, e.g., prone). Restriction in cervical range of motion or limited access to the airway due to injury, hard cervical collar, a halovest or bandages/dressings were additional factors suggestive of potential difficult airway management. Fifty-one patients had an indwelling AEC at the time of the reintubation procedure.

Forty-seven of 51 AEC patients had successful AEC-assisted reintubation (92%, Table 1), with 41 of 47 on the first attempt and thus an 87% first-pass success rate. Five patients required two attempts to pass the ETT via the AEC, and one patient required three attempts (each with a smaller diameter ETT). Of the four AEC failures, three patients had the AEC inadvertently removed during the reintubation process, and in the fourth patient the ETT could not be passed over the AEC despite progressive ETT downsizing, lubrication, and counterclockwise rotation of the ETT (marked laryngeal edema noted by fiberoptic bronchoscopy during reintubation). Reintubation of these four patients included the Fastrach LMA^TM in two patients, fiberoptic bronchoscopy in one patient, and conventional laryngoscopy in one patient who required four attempts. Seven patients suffered hypoxemia, with mild desaturation (Spo₂ <90%, n = 3) or severe desaturation (Spo₂ <70%, n = 4), during the reintubation process. Three of the 4 patients who developed severe hypoxemia were the AEC failures, and each experienced bradycardia (<40 bpm) and concomitant hypotension during the reintubation process. Only two patients who underwent successful AEC-assisted reintubation experienced severe reduction of the heart rate while resecuring the airway (one hypoxemia induced).

All reintubations were performed by an attending anesthesiologist alone (n = 23) or by an anesthesiology resident under direct supervision of an attending anesthesiologist (n = 28). The attending alone and attending/resident groups had similar reintubation success rates via the indwelling AEC. Three cases of inadvertent AEC migration out of the trachea during the reintubation process occurred: two cases handled by the resident/attending and one handled by the attending physician alone. The relatively low failure rate did not allow statistical analysis to identify any differences between resident and attending staff.

Forty-one percent of the AEC-assisted reintubations in 51 patients occurred within 2 h of the initial extubation, representing an overall rate of 6% (21 of 354 patients). The remaining 30 extubation failures with an indwelling AEC occurred beyond 2 h postextubation, primarily between 2 and 10 h. Once the decision to reintubate the trachea was made, administration of oxygen was provided by bag-mask ventilation in the majority of patients (44 of 51) by the anesthesia airway team, with the AEC lateralized to the corner of the mouth to optimize the mask seal. The remaining seven patients had 3–6 L of oxygen flow provided directly via the AEC, in lieu of bag-mask support. Direct administration of oxygen via the AEC effectively kept the seven patients' oxygen saturation >90% in each case, but this method required a brief disconnection of oxygen flow during the initial passing of the ETT over the indwelling AEC. High-pressure jet ventilation via the AEC was not used in any of the cases.

Patient preparation for AEC-assisted reintubation included no medication or local anesthesia applied topically to the upper airway (27%). The remaining patients received light-to-moderate doses of sedative-hypnotic drugs: midazolam 0.01–0.02 mg/kg, 1–3 mg total (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 trachea was facilitated with laryngoscopy to open the orohypopharynx in three-quarters of the patients. The remaining patients underwent manual jaw thrust/lingual retraction to assist with ETT passage over the AEC. Only two patients received neuromuscular blocking drugs to assist in the intubation procedure over the AEC; in the remaining patients, spontaneous ventilation was maintained.

Thirty-six patients (second group) required reintubation after their AEC had been removed. Eighteen of these 36 patients (50%) were intolerant of extubation within 120 min, 4 patients between 2 and 4 h, and 14 patients succumbed to reintubation beyond 4 h. These patients proved worthy of their designation as "known or suspected difficult airway," since the vast majority required multiple attempts to resecure the airway (three or more attempts with laryngoscopy plus the accessory device/technique, 77%) when compared with only one patient with the indwelling AEC who required three attempts. Table 2 illustrates the conventional and accessory airway devices that were required to assist the practitioner in resecuring the patients' airways.

The 14% first-pass reintubation success rate (first attempt 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). Nearly all (90%) of the non-AEC group required an accessory airway device or an advanced technique to successfully reestablish the airway (Table 3). Of note, after failure to intubate the trachea in four patients, despite concerted attempts with accessory devices, a surgical airway was required. Two of these four patients received bag-mask ventilation during the establishment of the surgical airway, and two patients had concurrent and successful ventilation and oxygenation via an LMA during placement of the surgical airway.

Oxygen desaturation in the non-AEC group was common during the reintubation process, with the nadir of <90% Spo₂ occurring in 50% of the patients; 40% of these suffered severe hypoxemia (Spo₂ <70%, Table 3). Esophageal intubation was more common in the non-AEC group (18% to 0%), as was hypoxemia-driven bradycardia with profound hemodynamic deterioration. Table 3 compares the various complications of the reintubation procedure between those reintubated with and without an indwelling AEC.

	DISCUSSION

Top Abstract Introduction METHODS RESULTS DISCUSSION REFERENCES

 
In the high-risk extubation patient with known or suspected airway management difficulties, development of a strategy to maintain access to the airway and to offer the safety of reversibility if the extubated state is not tolerated should be considered (1). This strategy will depend, in part, on the surgical and medical conditions of the patient, on the previous airway procedures and current airway status, as well as on the skills and preferences of the practitioner (1). Reintubation of the trachea in the known or suspected difficult airway patient appears fraught with complications, as illustrated in this study by the group of patients who underwent extubation of their trachea over an AEC, had it subsequently removed when the reintubation risk was presumed to be low, yet later suffered extubation intolerance and were reintubated.

Postextubation hypoventilation, airway compromise, ventilation-perfusion inequalities, and obstruction due to fatigue may afflict the patient in the OR, in the PACU, and in particular in the ICU (3,4). Continuous access to the airway can be maintained via an AEC with the proximal tip secured to the patient's clothing or forehead (waterproof adhesive tape). This is well tolerated by most patients (90%) and thus is a valuable option, considering a reintubation rate that varies from 0.4% to 25% in the various PACU and ICU populations (3–7,14–21).

Currently, there are no evidence-based guidelines regarding the optimal period of time for maintaining airway access postextubation via an indwelling AEC. Experts have suggested at least 30–60 min or until the likelihood of reintubation is minimized (3,5,6,22–24). Unfortunately, our database suggests that a minimum of 30–60 min would underestimate the need for a reversible extubation in a significant number of these high-risk patients. Moreover, the potential for changes in the patient's clinical status makes it difficult to predict when the need for reintubation is minimized. This may be particularly true in the ICU population, who may suffer acute alterations in their cardiopulmonary, metabolic, or neurological status, or other critical medical/surgical issues that may influence their tolerance of extubation.

If the intolerance of the extubated state is based principally on the presence or potential accumulation of periglottic edema, then the patient may benefit from extending the duration of the indwelling AEC to 60–120 min. Periglottic edema contributing to airway compromise often occurs immediately upon extubation or within 10–45 min of extubation, although it has been noted that symptomatic laryngeal edema may develop as late as 8 h postextubation (14,15). Extending the duration of continuous airway access would seem prudent if the patient demonstrates cardiopulmonary pathology and other systemic illness. Difficult airway patients who have failed an extubation trial are typically handled by determining the previous extubation time and then extending it by a factor of two- to three-fold to provide a reasonable cushion for maintaining access in the event of failure. If mental or neurological status is compromised, especially when coupled with cardiopulmonary limitations, then extending the time to 12–24 h or beyond may provide a valuable safeguard.

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

Previous investigators who incorporated an airway catheter (3.7–4 mm ED) found it was well tolerated, affording reasonable comfort and allowing the patients to retain the ability to phonate and generate a secretion-clearing cough (3,6). The current database, again, reconfirms that the 11F (3.7 mm ED) is well tolerated in over 90% of patients and may serve a key role in resecuring an airway in the difficult extubation patient. Moreover, the two larger sized AEC, the 14F (4.7 mm ED) and the 19F (6.3 mm ED), which had not been previously reported for the difficult extubation patient, were useful for maintaining access to the airway and reintubating the trachea for a reversible extubation in this study. In this database, the larger 14F 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 largest sized AEC (19F), although an excellent conduit for reintubation or exchanging an ETT, had a significantly higher rate of patient discomfort (50%). Its use for maintaining a reversible extubation has been curtailed at the author's institution due to this higher rate of discomfort and patient dissatisfaction. Although AEC-assisted reintubation of the trachea is not guaranteed, the 92% success rate of both sizes of AEC is exceptional and compares favorably with the three previously published studies reporting AEC-assisted reintubation (27 of 29 attempts successful, 93%) (3,4,6).

The presence of the AEC to assist in reintubating the trachea is a major step toward improving safety in the difficult airway patient. This is well illustrated by a comparison of the complication rates of AEC-assisted reintubations and tracheal extubations in difficult airway patients who had had their AEC removed before their declaration of extubation intolerance (Tables 2 and 3). Despite this high success rate for AEC-assisted reintubation, the practitioner and the airway team must be prepared for the possibility that the patient may fail the extubation trial and require emergent or urgent intubation of the trachea by a means other than the AEC. Immediate access to conventional and advanced airway rescue devices and the presence of competent and experienced airway personnel capable of providing advanced airway management in this difficult airway population are imperative (25–32).

The limitations of this data analysis are that it was neither a randomized nor a blinded evaluation of AEC-assisted extubation of the difficult airway patient, nor did it compare one method of maintaining airway access to another. Removal of the indwelling AEC was based on the clinical determination that the risk of reintubation was diminished; thus, it was limited by the practitioner's individual experience and judgment and the unpredictable nature of the patient's clinical status. Some patients may have remained instrumented with the AEC longer than needed, whereas others may have prematurely lost the benefit of continuous airway access.

The optimal duration of continuous access to the airway after extubation in this patient population was not directly tested. Beyond conjecture and the author's experienced opinion, this data analysis provided nondefinitive evidence-based findings to assist the practitioner in answering this important question.

In summary, this practice analysis reconfirms that the AEC is an efficient method of maintaining continuous access to the airway after extubation, as it is well tolerated and potentially offers a clinically valuable conduit for reintubation, as reported by earlier, more limited reviews (3,4,6). Further, in the taller patient, the medium-sized AEC (14F, 4.7 mm ED) may be a useful alternative to the smaller adult version (11F, 3.7 mm ED), as both sizes appear to be well tolerated by most patients. Complications of resecuring the airway in the known or suspected difficult airway are relatively common, especially when continuous airway access is not preserved. The optimal time for maintaining access to the airway postextubation should be addressed in further studies.

	Footnotes

 
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., Hartford Hospital, Hartford, CT 06015. Address e-mail to tmort{at}harthosp.org.

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This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a colleague Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Mort, T. C. Search for Related Content PubMed PubMed Citation Articles by Mort, T. C. Related Collections Critical Care Airway Equipment