Cricothyroidotomy needle length is associated with posterior tracheal wall injury: A randomized crossover simulation study (CONSORT).

Background: Cricothyroidotomy is the final strategy in the "cannot intubate, cannot oxygenate" scenario, but half of needle cricothyroidotomy attempts result in failure. The most frequent complication in needle cricothyroidotomy is posterior tracheal wall injury. We hypothesized that needle length is related to posterior wall injury and compared needle cricothyroidotomy with a commercial kit to a modified shorter needle to evaluate success and posterior wall injury rates.

Methods: The commercial kit has a needle stopper to prevent posterior wall injury, with a penetrating length of 25 mm. We made long stopper to shorten the length by 5 mm (net 20 mm penetrating length). Residents were recruited, received a lecture about cricothyroidotomy and practiced needle cricothyroidotomy using the commercial kit on a simulator. They then performed cricothyroidotomy using the commercial kit or the shorter needle on an ex-vivo porcine larynx covered with artificial skin. An intra-tracheal endoscope recorded the procedure. The video was evaluated for success/failure or posterior wall injury by independent evaluators. Larynxes with a distance from the outer surface to the inner lumen exceeding 13 mm were excluded. The distance in each larynx was measured by dissection after the study. Success and posterior wall injury rates were analyzed using Fisher exact test (P < .05 was statistically significant).

Results: Forty-seven residents participated in the study. Data for two residents were excluded. There was no statistically significant difference in success rate between the commercial kit (100%, 45/45) and the shorter needle (91%, 41/45, P = .12). Failure was defined if the needle tip did not reach the lumen in four trials. Cannulated but complicated by posterior wall injury occurred in 33% (15/45) with the commercial kit and 5% (2/43) with the shorter needle (P < .01).

Conclusion: During needle cricothyroidotomy, force is needed for the needle to penetrate the cricothyroid ligament. The advancing needle sometimes cannot be stopped after penetrating the cricothyroid ligament. These data suggest that needle length is associated with posterior wall injury.