Minerva Anestesiol. 2016 Feb;82(2):236-9. Epub 2015 Jul 1.

Could “safe practice” be compromising safe practice? Should anesthetists have to deflate the cuff of the endotracheal tube before extubation?

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Deflation of the cuff of the endotracheal tube (ETT) before extubation is considered standard of care and safe practice. It is entrenched in the mind of every anesthesiologist that there is no safe alternative to deflating the cuff of the ETT before removing it because of the risk of laryngeal injury associated with ‘pulling the tube’ without prior cuff deflation. This concern prevents any critical assessment of the rationale of this presumably ‘safe’ practice.

 

In fact, the standard practice of deflating the cuff before extubation has definite disadvantages. If a ‘de-blocked’ ETT cannot immediately be removed because the patient bites down on it, ‘silent’ aspiration around the ETT may occur. At the moment of cuff deflation, positive airway pressure is lost, and effective lung inflation and recruitment prior to extubation cannot be performed. This hinders the generation of an ‘artificial cough’, thereby impairing effective removal of secretions from glottic and subglottic areas during extubation. All of these factors can be expected to increase the potential for post-extubation hypoxemia, airway obstruction, laryngospasm, and atelectasis.

 

Back in 2006, Shamsai reported his ‘new’ technique of removing the ETT without deflating the cuff [1]. He stated to no longer experiencing the typical sequelae of extubation (e.g., laryngospasm, bronchospasm, coughing, breath-holding, cyanosis) since he had begun using this practice. Indeed, the technique of not deflating the cuff before tracheal extubation counteracts some of the disadvantages of the standard practice. The risk of tracheal aspiration ‘around the tube’ will be minimized in those situations in which the ETT cannot be removed. The sealed airway allows maintenance of positive airway pressure until the very moment of extubation, and it allows effective lung inflation and recruitment immediately before extubation. Experimental lung inflation decreased laryngeal adductor excitability [2, 3]. This may possibly reduce the risk of post-extubation laryngospasm. Effective lung recruitment before extubation may decrease the incidence of postoperative hypoxemia, atelectasis and, in turn, pulmonary complications. It may counteract the development of pulmonary atelectasis associated with the routine use of high inspired oxygen concentrations at the time of extubation. Increasing airway pressure up to 30-40 cm H2O immediately before extubation ensures that removal of the ETT reliably occurs during the expiratory phase. It generates an effective ‘artificial cough’ which expels secretions and blood from the glottic and subglottic areas during tracheal extubation which can be expected to decrease the risk of laryngospasm and, in turn, the incidence of post-extubation airway obstruction. All of these factors might reduce the overall risk of immediate post-extubation and postoperative respiratory and pulmonary complications. Noteworthy, there is lack of type I evidence supporting the routine practice of deflating the cuff of the ETT before tracheal extubation [4].

 

The obvious concern with not deflating the cuff before extubation is the potential for laryngeal trauma. Monitoring of cuff pressure is an absolute prerequisite of this ‘new’ technique. If cuff pressure is kept between 25 and maximally 30 cm H2O (which is in accordance with present recommendations), visual inspection of a non-deflated low-pressure, high-volume cuff following extubation shows a remaining rather small, highly compressible cuff volume around the ETT which is unlikely to carry per se the risk of producing laryngeal trauma. Accidental extubation in intensive care units is not all that rare. However, to my knowledge there is no documentation of a causal relationship between accidental extubation (in the presence of an inflated cuff with frequently unmonitored cuff pressure) and subsequent laryngeal injury.

 

In my opinion, definite shortcomings associated with the traditional technique of deflating the cuff before extubation, lack of type I evidence supporting such practice, and definite advantages associated with the ‘new’ technique, merit a prospective trial on this issue. After all, just as insisting to demonstrate effective mask ventilation before administering the muscle relaxant may compromise safe practice [5], the ‘safe’ practice of insisting to deflate the cuff of the ETT before extubation may possibly also be compromising safe practice.

 

References

[1]. J. Shamsai, A new technique for removal of endotracheal tube, Anesth. Analg. 103 (2006) 1040.

[2]. T. Ikari, C.T. Sasaki, Glottic closure reflex: control mechanisms, Ann. Otol. Rhinol. Laryngol. 89 (1980) 220-224

[3]. J.E. Aviv, I. Sanders, H.F. Biller, Abductor vocal cord spasm, Otolaryngol. Head. Neck. Surg. 102 (1990) 233-238.

[4]. L.J. Saidman, Editor’s note, Anesth. Analg. 104 (2007) 104:285.

[5]. I. Calder, S.M. Yentis, Could “safe practice” be compromising safe practice? Should anaesthetists have to demonstrate that face mask ventilation is possible before giving a neuromuscular blocker? Anaesthesia. 63 (2008) 113-115