Cannula cricothyroidotomy in simulated ‘cannot intubate, cannot oxygenate’ scenarios using a live anaesthetised pig model

Abstract

Despite limited evidence to guide cannot oxygenate, cannot oxygenate (CICO) management, support is growing for scalpel over cannula-based techniques.1 The Australian and New Zealand College of Anaesthetists continues to support both techniques and encourages regular CICO training.2 Our group conducts training where live anaesthetised pigs are used to recreate CICO scenarios. The porcine neck represents an impalpable anatomy model. We report a study of cannula cricothyroidotomy in simulated CICO scenarios using live anaesthetised pigs. Ethics approval was gained from both institutions, and all participants gave consent for inclusion in the study. Forty two anaesthetists were given comprehensive teaching based on the Royal Perth Hospital (RPH) CICO algorithm3. After cadaver training, each candidate was placed into a high-fidelity airway simulation. Under the management of veterinary anaesthetists, pigs were rendered apnoeic. When Spo2 decreased to 92%, candidates were instructed to gain immediate front-of-neck access after the RPH CICO Algorithm assuming impalpable anatomy (up to three attempts at cannula cricothyroidotomy within 1 min followed by a scalpel–finger–cannula technique). Percutaneous cannula cricothyroidotomy had a low success rate, with ability to re-oxygenate a hypoxaemic porcine model (SpO2>90%); highest at first attempt (first=29%). Second and third attempts had a declining ability to re-oxygenate (21% and 12%, respectively) because of critical hypoxaemia necessitating euthanasia. Percutaneous attempts (first, second, third) were started at 44, 84, and 131 s, respectively. With a successful first cannula, average time to re-oxygenation was 110 s. After three failed percutaneous cannulas, all participants performed a scalpel–finger–cannula technique, started at 166 s on average with a 44% re-oxygenate rate. Average pig weight was 16.2 kg (range 11–24 kg) with an internal tracheal diameter of 11 mm (range 9–15 mm). By following a CICO management algorithm, cannula cricothyroidotomy and scalpel-finger-cannula technique can be used to successfully ventilate and re-oxygenate a hypoxaemic ‘impalpable anatomy’ pig model. Percutaneous cannula cricothyrotomy can be swift but participants may fixate on performing additional percutaneous attempts at the expense of transitioning to scalpel-finger-cannula. Live animal simulation is an invaluable training tool that may help prepare anaesthetists for this rare, life-threatening emergency.