The efficacy of spontaneous and controlled ventilation with various cricothyrotomy devices: a quantitative in vitro assessment in a model lung.

Background: Guidelines for the management of a difficult airway recommend performing a cricothyrotomy in a "can't intubate/can't ventilate" situation. We investigated the tidal volumes delivered by controlled and spontaneous ventilation by seven commercially available cricothyrotomy sets (cuffed: Quicktrach II, Portex Cricothyroidotomy Kit, and Melker cuffed cannula and uncuffed: Airfree, 4.0-mm ID Quicktrach, 6.0-mm inner diameter Melker, and 13-gauge Ravussin cannula) and two improvised devices (14-gauge intravenous cannula and spike and drip chamber device).

Methods: A LS800 model lung, set at different values for compliance and resistance and modified with different upper airway diameter, was ventilated via the respective cricothyrotomy device mechanically and using a self-inflating bag. With the 13-gauge Ravussin cannula and the 14-gauge intravenous cannula, a Manujet injector was used for jet ventilation. Spontaneous ventilation was simulated with a Michigan 560i lung.

Results: During controlled or manual ventilation, all cuffed cricothyrotomy devices yielded adequate tidal volumes. Uncuffed devices provided tidal volumes≥300 mL only with an upper airway diameter of ≤3 mm. With a Manujet injector, adequate tidal volumes required an upper airway diameter between 3 mm and 5 mm. A spike and drip chamber device does not provide suitable emergency airway access. Spontaneous ventilation at adequate inspiratory pressure levels required a device inner diameter of at least 4 mm.

Conclusion: As expected, cuffed cricothyrotomy devices yield the best results during controlled, manual, and spontaneous ventilation. With uncuffed cricothyrotomy devices, ventilation becomes ineffective when the upper airway obstruction allows for an upper airway diameter>3 mm.