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September 1, 2013 Volume 77, Number 9
Extubation of the Difficult Airway: It’s Time to Focus on Research! John Hsih, M.D., Elizabeth Cordes Behringer M.D.


The newly revised 2013 Practice Guidelines for Management of the Difficult Airway includes Section IV: Considerations for Extubation of the Difficult Airway.1 The following is a summary of extubation principles recommended by the ASA Task Force on Management of the Difficult Airway in the 2003 and 2013 versions of the practice guidelines. 1,2


Despite the decade between publication of the 2003 and the current 2013 guidelines, there remains insufficient scientific evidence to assess the benefits of a specific extubation strategy in management of a difficult airway. There is general agreement that a pre-formulated extubation strategy should be considered. These strategies will depend on the surgery, condition of the patient and the skills of the anesthesiologist. Strategies can include the following: merits of an awake versus deep extubation, assessment of factors that may cause difficulty in ventilation post-extubation, and a pre-formulated plan for airway management should the patient be unable to maintain an adequate airway post-extubation.


The task force also strongly recommends consideration of short-term use of a device (i.e., airway exchange catheter or conduit) that can facilitate immediate reintubation should the need arise.1,2 Examples of conduits are supraglottic devices that can be used for ventilation, fiberoptic airway inspection and reintubation, as needed. An airway exchange catheter (AEC) is a semi-rigid, hollow device inserted through the endotracheal tube into the trachea above the level of the carina prior to extubation. A properly inserted and maintained airway exchange catheter can remain in situ, providing the potential for “reversible extubation.” In addition, the hollow core of the device can provide a temporary means of oxygenation and ventilation. The use of airway exchange catheters or conduits providing the potential for “reversible extubation” has been supported by myriad scientific reports.3-9


In a key article on the efficacy of airway exchange catheters, Mort performed an observational analysis of a prospectively collected difficult airway quality improvement database.5 Patients who were extubated over an AEC due to a known or presumed difficult airway were included in the study. The vast majority of patients studied were located in an intensive care unit. Mort collected the time to reintubation, the number of reintubation attempts, the method used to secure the airway, the incidence of hypoxemia during reintubation and the complications encountered during reintubation.


Fifty-one patients with an indwelling AEC required reintubation following failed extubation. Forty-seven of these patients were successfully reintubated over the airway exchange catheter (92 percent). Eighty-seven percent were reintubated on the first attempt (41/47 patients). There were four failures to reintubate using the airway exchange catheter. The AEC was inadvertently removed from the glottis during reintubation in three patients and significant laryngeal edema precluding endotracheal tube advancement in one patient.


The table below highlights the significant difference in complications associated with reintubation with or without the presence of an AEC.5


 

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)

<0.02

Hypoxemia during reintubation (SPO2<90%)

8%b (4)

50% (18)

<0.01

Severe hypoxemia during reintubation (SPO2<70%)

6%a (3)

19% (7)

0.05

Bradycardia (heart rate <40) with hypotension

4% (2)

14% (5)

<0.05

Multiple intubation attempts (≥3) including the

placement of an accessory airway device

10%b (5)

77% (28)

<0.02

Esophageal intubation

0

18% (6)

 

Rescue airway device/technique

6%a (3)

90% (32)

<0.01

 

a 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


Mort TC. Continuous airway access for the difficult extubation: the efficacy of the airway exchange catheter. Anesth Analg. 2007. Nov;105(5):1357-62.

 

Based on the current literature as well as the ASA difficult airway task force recommendations, AECs remain an essential consideration in any extubation strategy involving a difficult airway. As such, these devices demand immediate availability in a difficult airway cart located in all areas where advanced airway management is performed. Clinician education and training on AECs as part of an extubation strategy are also essential to their safe and effective use.


Recommendations for extubation of the difficult airway have remained unchanged since the last iteration of the guidelines published in 2003.2 However, complications surrounding failed extubation are well described and significant.9-12 Such complications are particularly egregious outside of the operating room setting. Menon and colleagues recently reported the occurrence and complications of reintubation in criticially ill adult patients at their institution. Of 2,007 intubated, critically ill adult ICU patients, the authors found that nearly 20 percent required out-of-operating-room reintubation. Reintubation was associated with higher mortality, longer ICU stay and higher cost. In the ICU setting, identification of a difficult airway at the time of reintubation was associated with a higher mortality.13


The landmark Fourth National Audit project (NAP4) was published in 2011 as a joint project of the Royal College of Anaesthetists and the Difficult Airway Society (DAS).10,11 Major complications of airway management throughout O.R.s, PACUs, ICUs and ERs in the United Kingdom were compiled over a one-year period. One-third of the complications documented were extubation-related. The authors identified several recurrent issues surrounding extubation-related airway complications, including inadequate strategies for airway management, inadequate assessment of risk factors for airway difficulty and overall failure to plan in the event of difficulty.10,11 The NAP4 authors stressed the importance of developing preplanned strategies, including plans for extubation of the difficult airway in order to improve patient safety and outcomes.


In a recent review, Cook and colleagues underscored the high-risk nature of airway management outside of the O.R.14 Recently published studies, including the NAP4 findings, indicate that complications, particularly in intensive care, occur more frequently after airway placement (e.g., extubation failure, unplanned or partial extubation) than at the time of placement. Lack of appropriate personnel, equipment and monitoring, including capnography, are preventable and reversible causes of airway-related morbidity, particularly in the ICU setting. Although airway management outside the O.R. remains a high-risk procedure, the optimal organizational structure, rescue procedures, algorithms and appropriate personnel have not been adequately defined.14


A recent excellent review on extubation and extubation failure by Cavallone and Vannucci concluded that a lack of substantial scientific literature has hindered the publication of evidence-based extubation guidelines.12 This observation explains the lack of evolution in extubation-related recommendations in the current version of the Practice Guidelines for Management of the Difficult Airway.1


The Difficult Airway Society (DAS) recently published a consensus of expert opinion with regard to extubation of the difficult airway.15 The authors acknowledged that the need for such guidelines are evident, but large clinical trials of extubation strategies are lacking. The DAS extubation guidelines draw much-needed attention to the importance of preplanned extubation strategies.15


Progress in the area of extubation of the difficult airway is critical as the field of airway management continues to evolve. Such progress will depend upon the publication of high-quality and interventional studies as well as the development of optimal collaborative organization related to extubation outside the O.R, rescue techniques and extubation-related algorithms.14



John Hsih, M.D. is Chief Resident, Department of Anesthesiology, Cedars-Sinai Medical Center, Los Angeles, California.


Elizabeth Cordes Behringer, M.D. is Professor of Anesthesiology, Director, Critical Care Education, Director, Fellowship in Critical Care, Department of Anesthesiology Cedars-Sinai Medical Center, Los Angeles, California. She is Past President, Society for Airway Management.



References:


1. Apfelbaum JL, Hagberg CA, Caplan RA, et al.; American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Practice guidelines for management of the difficult airway: an updated report. Anesthesiology. 2013;118(2):251-270.


2.Caplan RA, Benumof JL, Berry FA, et al.; American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Practice guidelines for management of the difficult airway: an updated report. Anesthesiology. 2003;98(5):1269-1277.


3. Mort TC, Vithiananthan S. Extubation of the difficult airway over an airway exchange catheter: relationship of catheter size and patient tolerance [abstract 119]. Crit Care Med. 1999;27(1 suppl):A72.


4. Atlas G. A high-risk endotracheal tube exchanger. Anesth Analg. 2002;95(3):785.


5. Mort TC. Continuous airway access for the difficult extubation: the efficacy of the airway exchange catheter. Anesth Analg. 2007;105(5):1357-1362.


6. Cooper RM, Levytam S. Use of an endotracheal ventilation catheter for difficult extubations [abstract]. Anesthesiology. 1992;77(3A):A1110.


7. Cooper RM: The use of an endotracheal ventilation catheter in the management of difficult extubations. Can J Anaesth. 1996;43(1):90-93.


8. Loudermilk EP, Hartmannsgruber M, Stoltzfus DP, Langevin PB. A prospective study of the safety of tracheal extubation using a pediatric airway exchange catheter for patients with a known difficult airway. Chest. 1997;111(6):1660-1665.


9. Cooper RM, Kahn S. Extubation and re-intubation of the difficult airway. In: Hagberg CA, ed. Benumof and Hagberg’s Airway Management. 3rd ed. Philadelphia: Elsevier; 2013:1018-1046.


10.Cook TM, Woodall N, Frerk C; Fourth National Audit Project. Major complications of airway management in the UK: results of the Fourth National Audit Project of the Royal College of Anaesthetists and the Difficult Airway Society. Part 1: anaesthesia. Br J Anaesth. 2011;106(5):617-631.


For a complete list of references, please refer to the back of the online version of the ASA NEWSLETTER at asahq.org or email communications@asahq.org.


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