How much force is required to dislodge an alternate airway?

INTRODUCTION: Endotracheal tube (ETT) dislodgment is a potentially catastrophic adverse event. Newer alternate airway devices-esophageal-tracheal Combitube (ETC), King laryngeal tube disposable airway (King LT), and laryngeal mask airway (LMA)-are easier to insert, but their relative extubating forces remain unknown.

OBJECTIVE: To examine the applied forces required to dislodge an ETC, King LT, LMA, and ETT.

METHODS: We used five recently deceased adult unembalmed cadavers. In random order, we sequentially inserted an ETC, King LT, LMA, and standard ETT. Because commercial tube holders are not designed for all alternate airways, we secured the devices with a standard adhesive tape method. Using a precision digital force measuring device, we measured the minimum manually applied axial force (lb) that dislodged each airway device at least 4 cm. We compared required dislodgment forces between airway devices using a mixed-effects regression model, adjusting for cadaver height, weight, neck circumference, and thyromental distance.

RESULTS: Characteristics of the cadavers were as follows (median, interquartile range [IQR]): height 172 cm (167-177), weight 98 kg (84-120), neck circumference 46.5 cm (41-52), and thyromental distance 7.5 cm (7.5-8). Required axial dislodgment forces for each airway device were as follows (median, IQR): ETC 28.3 lb (19.0-28.6), King LT 12.5 lb (11.7-13.3), LMA 18.3 lb (14.0-21.9), and ETT 14.4 lb (13.5-22.1). The ETC required twice as much dislodgment force as the ETT (adjusted difference 16.7 lb, 95% confidence interval [CI]: 8.3 to 25.1). The King LT and LMA dislodgment forces were similar to that of the ETT (King LT vs. ETT adjusted difference 5.9 lb, 95% CI: -2.4 to 14.2; LMA vs. ETT 8.1 lb, 95% CI: -0.2 to 16.5).

CONCLUSION: In a cadaver model of unintended airway dislodgment, the ETC required the most force for dislodgment. The King LT and LMA performed similarly to a standard ETT.