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Original Article

Management of unanticipated difficult intubation: a survey of current practice in the Oxford region

Bokhari, A.; Benham, S. W.; Popat, M. T.

Author Information
European Journal of Anaesthesiology: February 2004 - Volume 21 - Issue 2 - p 123-127

Abstract

Unanticipated difficulty in maintaining a patent airway and placing an endotracheal tube in an anaesthetized patient has always been a cause of concern to anaesthesiologists. The reported incidence of difficult laryngoscopy varies from 2-8% in the North American literature [1] to 1-4% in the UK [2]. It is estimated that overall in about 1 : 20 laryngoscopies, it is not possible to see any part of the vocal cords when using a conventional laryngoscope [1,2], and this would equate to a Cormack and Lehane Grade 3 or 4 [3]. The incidence of difficult intubation is estimated at 1 : 100 in the general population. Failed intubation is much less common, i.e. 1 : 2000 [1,4].

Tunstall first advocated a reasoned approach to airway management 25 yr ago with his difficult airway drill [5]. In 1993, the American Society of Anesthesiologists developed practice guidelines for the management of the difficult airway using an algorithm [6]. More recently, the Canadian Airway Focus Group has produced a systematic review of this subject [1]. There is a general consensus that if once the proper insertion of endotracheal tube fails with an anaesthetist's best or optimal attempt at laryngoscopy, a second back-up plan (Plan B) should be activated as early as possible without further risk to the patient [4]. Since the patient is paralysed, the options are to perform blind or fibreoptic-assisted intubation under general anaesthesia. Any of the conduit airways or the classic laryngeal mask airway (Intavent Ltd., Reading, Berks, UK) or intubating laryngeal mask airway can be used to assist blind or fibreoptic intubation. The options available depend on the training and previous experience of the anaesthesiologist. Little information has been published about the prevalence of the use of these techniques by anaesthesiologists in the UK. Hence, we conducted a questionnaire survey of anaesthesiologists in the Oxford region based on a 'can't intubate, can ventilate' scenario as a tool to ascertain anaesthesiologists' preference for optimizing laryngoscopy and techniques they would use to accomplish intubation if above attempts failed. Our aim was to gain insight into the training and requirements for future training of anaesthesiologists of all grades in teaching and district general hospitals.

Methods

A postal questionnaire (Appendix) was sent to all (n = 181) anaesthesiologists in one teaching and three district general hospitals in the Oxford region of the UK. The questionnaire consisted of six sections. The first section asked the grade of the anaesthesiologist and the number of years spent in anaesthetic practice. The scenario was then described and four sequential questions were asked aiming to determine the optimal attempt at laryngoscopy, technique of choice to secure intubation, the reasons for this choice and the reasons for not choosing the others, respectively. The last section provided space for comments, if any. Statistical analysis was carried out employing χ2-test; P < 0.05 was considered significant.

Results

Overall

Of the 181 questionnaires sent, we received 143 (79%) completed replies from 13 senior house officers, 40 specialist registrars (training years 1-4), 13 non-consultant career grade and 77 consultant anaesthesiologists. The response was >72% for all grades. The median (IQR (range)) length of time in anaesthetic practice was 2 (1-5.5 (1-12)) yr for senior house officers, 5.5 (3.5-9 (2-25)) yr for specialist registrars, 14 (11.5-20 (3-32)) yr for non-consultant career grades and 17 (13-23 (8-37)) yr for consultants.

After intravenous induction and neuromuscular block in an elective situation, when an unanticipated Cormack and Lehane Grade 3 or 4 laryngoscopy was encountered, 60/143 (41.9%) would call for help, 123/143 (86%) would use an optimal sniffing position, 127/143 (88.8%) would use an optimal external laryngeal manipulation, 107/143 (74.8%) would have one change in length of laryngoscope blade, 68/143 (47.5%) would have one change in the type of the blade and 141/143 (98.6%) would use a gum-elastic bougie to gain an optimal attempt at intubation.

When the above attempts fail, overall 129/143 (90%) of anaesthesiologists had an alternative plan (Plan B); while 14/143 (10%) had no plan. Fibreoptic techniques were more commonly planned: 92/143 (64%); 73/143 would attempt fibreoptic nasal or oral intubation, 12/143 would use fibreoptic intubation through the laryngeal mask and 7/143 would attempt fibreoptic intubation through the intubating laryngeal mask. Blind techniques were less common: 37/143 (26%); 11/143 would use blind intubation through the laryngeal mask and 26/143 would attempt blind intubation through the intubating version.

Consultants vs. other grades of staff

Overall, consultants were more likely (P = 0.0009) to choose fibreoptic techniques than blind methods or had no Plan B compared to all other grades. Of the consultants, 59/77 would use fibreoptic techniques, 17/77 would use blind techniques and only 1/77 had no Plan B. While among 66 anaesthesiologists of all other grades, 33/66 would use fibreoptic techniques and 20/66 would use blind techniques. However, 13/66 had no Plan B (Fig. 1).

Figure 1
Figure 1:
Choice of technique - consultants vs. all other grades:P = 0.0009; ▪: consultants (n = 77); □: other grades (n = 66); FOI: fibreoptic intubation.

Teaching vs. district general hospitals

The differences among anaesthesiologists in teaching and district general (i.e. non-teaching) hospitals were not significant (P = 0.87).

Reasons for choice of a technique

Overall, previous experience with a technique was the predominant reason for the choice of any technique (Fig. 2).

Figure 2
Figure 2:
Reasons for choosing a particular technique - ▪: previous experience; □: availability;JOURNAL/ejanet/04.02/00003643-200402000-00007/ENTITY_OV0158/v/2017-07-27T035946Z/r/image-png: ease of use; FOI: fibreoptic intubation; LMA: laryngeal mask airway; ILMA: intubating laryngeal mask airway.

Reasons for not choosing a technique

Lack of experience and training were the two most common reasons for not choosing any technique. Unavailability of the intubating laryngeal mask airway was expressed as an additional factor precluding its use for fibreoptic or blind intubation (Fig. 3).

Figure 3
Figure 3:
Reasons for not choosing other techniques - ▪: lack of experience; □: lack of training;JOURNAL/ejanet/04.02/00003643-200402000-00007/ENTITY_OV0158/v/2017-07-27T035946Z/r/image-png: difficulty in use; ▤: unavailability; FOI: fibreoptic intubation; LMA: laryngeal mask airway; ILMA: intubating laryngeal mask airway.

Discussion

Difficulties in maintaining a patent airway and placing an endotracheal tube can sometimes lead to morbidity and mortality. In the UK, the first Report of a Confidential Enquiry into Perioperative Deaths stated that one in three anaesthetic-related deaths was due to failure to intubate the trachea [7]. Exact figures are unknown, but data from the American Closed Claims Study showed that difficult intubation claims accounted for 17% of the total adverse respiratory claims; 75% of these were preventable or due to substandard care and 85% resulted in death or brain death. One danger of persistent attempts at intubation is the trauma, oedema and bleeding that is caused to the upper airway. Eventually, an airway that could be managed by mask ventilation becomes unmanageable. This sequence of events has been repeatedly highlighted in closed claims where patients have become hypoxic with repeated intubation attempts [8].

In the last few years, a number of new devices and important modifications have become available to assist the anaesthesiologists when dealing with a difficult airway. Since tracheal intubation became a routine part of anaesthetic practice, two of the most important developments that have been suggested [9] are flexible fibreoptic laryngoscopy and the introduction of the laryngeal mask airway [10,11]. An anaesthetist experienced in performing fibreoptic intubation should use it as an early option in the airway management plan. This will avoid trauma to the upper airway from repeated failed attempts at direct laryngoscopy and intubation. This is crucial because, if fibreoptic intubation is considered late, there is every chance that it may fail due to the presence of blood and secretions. Studies have generally confirmed the safety and efficacy of fibreoptic intubation in this scenario, although failures are recorded [12,13]. Hence, it was not surprising that most (64%) anaesthesiologists surveyed planned to undertake fibreoptic techniques when optimal attempt at laryngoscopy failed. A survey of American anaesthesiologists also confirmed that fibreoptic techniques were the most favoured technique in this scenario [14]. However, it is to be emphasized that in Oxford a structured programme for training in fibreoptic endoscopy has been available for some years. This may skew the findings of this survey and the possibility of major differences around UK and Europe cannot be excluded.

The standard laryngeal mask airway is probably the single most important development in airway management in the last 20 yr [11]. This device is now an integral part of most difficult airway algorithms [9]. Early reports of the laryngeal mask being used as an intubating conduit have led to the development of the intubating version [15]. A recent multicentre case series of 500 patients demonstrates success of the device, both as a means of lung ventilation and as a conduit to intubation. The incidence of first time endotracheal placement is approximately 75% increasing to 95% or more after three attempts. The intubating laryngeal mask airway is easy to insert, more so than the classical mask in inexperienced hands, and, in particular, when the neck has to be maintained in the neutral position [16]. There are numerous reports of the intubating laryngeal mask being used successfully in known difficult airway situations, both elective and unanticipated. The intubating laryngeal mask was shown in our survey to be used least often, the major reasons stated being lack of training and experience. Another reason that was highlighted was its unavailability. On further enquiry, only three out of seven operating theatre suites in our survey had an intubating laryngeal mask available and that was only as part of the 'difficult intubation' trolley. We feel strongly that as with all anaesthetic equipment, unless the intubating laryngeal mask is available for routine use one cannot gain enough experience to use it in emergency situations.

The need for training in airway management and fibreoptic techniques cannot be overemphasized. Trainees were less skilled in the use of fibreoptic techniques and would use blind intubation through the laryngeal mask or the intubating version. Moreover, a reasonable (one in five) number of trainees still rely on senior colleagues to rescue them when conventional airway techniques fail. Difficult airway management and fibreoptic intubation training is not a mandatory component of specialist registrar training at present in the UK. However, a proposal for a comprehensive training in airway management as part of the generic skills required during specialist training in anaesthetics is under discussion by the Royal College of Anaesthetists in the UK. A considerable number of consultants also used blind techniques for reasons of lack of training and experience with fibreoptic intubation. Continuing medical education courses should allow consultants the opportunity to train with these alternative devices.

Attempts are also being made by the UK Difficult Airway Society to introduce guidelines for the management of difficult airway scenarios (Henderson JJ - personal communication). However, any proposed management of difficult airway situation depends ultimately on training of anaesthesiologists of all grades in the use of flexible fibreoptic laryngoscope and other alternative devices.

References

1. Crosby ET, Cooper RM, Douglas MJ, et al. The unanticipated difficult airway with recommendations for management. Can J Anesth 1998; 45: 757-776.
2. Samsoon GLT, Young JRB. Difficult tracheal intubation: a retrospective study. Anaesthesia 1987; 42: 487-490.
3. Cormack RS, Lehane J. Difficult trachcal intubation in obstetrics. Anaesthesia 1984; 39: 1105-1111.
4. Benumof JL. Management of the difficult adult airway. Anesthesiology 1991; 75: 1087-1110.
5. Tunstall M. Failed intubation drill. Anaesthesia 1976; 31: 850.
6. Caplan RA, Benumof JL, Berry FA, et al. Practice guidelines for the management of the difficult airway. A report by the American Society of Anesthesiologists Task Force on the Management of the Difficult Airway. Anesthesiology 1993; 78: 597-602.
7. Buck N, Devlin HB. The Report of a Confidential Enquiry into Perioperative Deaths. London, UK: NCEPOD, 1987.
8. Cheyney FW, Posner KL, Caplan RA. Adverse respiratory events infrequently leading to a malpractice suits. A closed claim analysis. Anesthesiology 1991; 75: 932-939.
9. Finucane B. The difficult airway - a Canadian perspective. Can J Anaesth 1998; 45: 713-718.
10. Murphy PA. A fibreoptic endoscope used for nasal intubation. Anaesthesia 1967; 22: 489-491.
11. Brain AIJ. The laryngeal mask - a new concept in airway management. Br J Anaesth 1983; 55: 805-808.
12. Ovassapian A. Fibreoptic tracheal intubation in adults. In: Ovassapian A, ed. Fibreoptic Endoscopy and the Difficult Airway, 2nd edn. Philadelphia, USA: Lippincott-Raven, 1996: 72-103.
13. Heidegger T, Gerig HJ, Kreienbühl G. Validation of a simple algorithm for tracheal intubation: daily practice is the key to success in emergencies - an analysis of 13,248 intubations. Anesth Analg 2001; 92: 517-522.
14. Rosenblatt WH, Wagner PJ, Ovassapian A, Kain ZN. Practice pattern in managing the difficult airway by anaesthesiologists in the United States. Anesth Analg 1998; 87: 153-157.
15. Brain AI, Verghese C, Addey EV, Kapila A, Brimacombe J. The intubating laryngeal mask. II. A preliminary clinical report of a new means of intubating the trachea. Br J Anaesth 1997; 79: 704-709.
16. Baskett PJF, Parr MJ, Nolan JP. The intubating laryngeal mask. Results of a multicentre trial with experience of 500 cases. Anaesthesia 1998; 53: 1174-1179.

Appendix

Please tick ✓ current grade

❑ Consultant

❑ Non-consultant Career grade

❑ Specialist Registrar grade - year ❑

❑ Senior House Officer grade

Number of years in Anaesthetics ❑❑

Scenario: In an elective procedurerequiring tracheal intubation,you encounter an unanticipated difficult laryngoscopy (Grade 3 or 4).

Question 1: Which of the following would you consider?

Please tick ✓ your choice(s)

❑ Ask for senior help

❑ Use of optimal sniffing position

❑ Use of optimal external laryngeal manipulation

❑ One change in the length of the blade

❑ One change in the type of the blade

❑ Gum-elastic bougie

Question 2: The above manoeuvres failed but you were able to maintain bag and mask ventilation. If intubation was still required, which of the following techniques you would be confident in performing?

Please tick ✓ your first choice

❑ Blind intubation through laryngeal mask airway

❑ Fibreoptic guided intubation through laryngeal mask airway

❑ Fibreoptic nasal or oral intubation

❑ Blind intubation through intubating laryngeal mask airway

❑ Fibreoptic guided intubation through intubating laryngeal mask airway

❑ None of the above (please go straight to Question 4 and answer each column).

Question 3: What was/were the reason(s) for your first choice in above?

Please tick ✓ your choice(s)

❑ Previous experience

❑ Availability of equipment

❑ Ease of use

❑ Others ___________________________________

Question 4: What was/were the reason(s) for not choosing the alternative choices?

Please cross out the column for your choice given in Question 2 and tick ✓ your reason(s) for the rest.

TABLE

Table
Table

Comments:

Keywords:

INTUBATION, INTRATRACHEAL, laryngeal masks; RESPIRATORY INSUFFICIENCY, airway obstruction

© 2004 European Academy of Anaesthesiology