Ultrasound Improves Cricothyrotomy Success in Cadavers with Poorly Defined Neck Anatomy: A Randomized Control Trial.

BACKGROUND Misidentification of the cricothyroid membrane in a "cannot intubate-cannot oxygenate" situation can lead to failures and serious complications. The authors hypothesized that preprocedure ultrasound-guided identification of the cricothyroid membrane would reduce complications associated with cricothyrotomy. METHODS A group of 47 trainees were randomized to digital palpation (n = 23) and ultrasound (n = 24) groups. Cricothyrotomy was performed on human cadavers by using the Portex device (Smiths Medical, USA). Anatomical landmarks of cadavers were graded as follows: grade 1-easy = visual landmarks; 2-moderate = requires light palpation of landmarks; 3-difficult = requires deep palpation of landmarks; and 4-impossible = landmarks not palpable. Primary outcome was the complication rate as measured by the severity of injuries. Secondary outcomes were correct device placement, failure to cannulate, and insertion time. RESULTS Ultrasound guidance significantly decreased the incidence of injuries to the larynx and trachea (digital palpation: 17 of 23 = 74% vs. ultrasound: 6 of 24 = 25%; relative risk, 2.88; 95% CI, 1.39 to 5.94; P = 0.001) and increased the probability of correct insertion by 5.6 times (P = 0.043) in cadavers with difficult and impossible landmark palpation (digital palpation 8.3% vs. ultrasound 46.7%). Injuries were found in 100% of the grades 3 to 4 (difficult-impossible landmark palpation) cadavers by digital palpation compared with only 33% by ultrasound (P < 0.001). The mean (SD) insertion time was significantly longer with ultrasound than with digital palpation (196.1 s [60.6 s] vs. 110.5 s [46.9 s]; P < 0.001). CONCLUSION Preprocedure ultrasound guidance in cadavers with poorly defined neck anatomy significantly reduces complications and improves correct insertion of the airway device in the cricothyroid membrane.