[Comparison of ready-to-use devices for emergency cricothyrotomy : randomized and controlled feasibility study on a mannequin].

Background: According to various algorithms of airway management, emergency cricothyrotomy (coniotomy) represents the ultimate step for managing the difficult airway. As most physicians have limited experience with this technique several ready-to-use devices have emerged on the market with the aim of simplifying the procedure. However, they differ in details, such as configuration or the order of particular steps. Therefore, the intention of this randomized and controlled feasibility study was to test various sets and compare them to the classical surgical approach.

Methods: After obtaining informed consent German anesthesiologists who were also board-certified emergency physicians were asked to perform the cricothyrotomy procedure in a cervical mannequin (Frova Crico-Trainer, VBM Medizintechnik) in a randomized order using a scalpel, peripheral intravenous cannula and the commercial devices TracheoQuick, Airfree, Portex-Crico-Kit, Quicktrach I and Quicktrach II. Handling and duration of the procedures were analyzed utilizing the Wilcoxon signed-rank test. A p-value  < 0.05 was considered significant.

Results: A total of 20 anesthesiologists (11 residents and 9 specialists) with a mean age of 34 years were included in this study and all had the additional qualification of emergency physician, which enabled them to work in prehospital emergency medicine in Germany. Participants had been working in this field for an average of 29.9 months (range 6-84 months) performing a mean of 1.9 24 h shifts per month (range 1-6 shifts/month). Of the participants only 2 (10%) had performed a coniotomy in reality before. In this study surgical coniotomy required a median time of 35.4 s (range 30.0-61.8 s). No significant differences were seen when the cuffed devices Quicktrach II (median: 29.9 s, range 25.0-50.5 s) and Portex-Crico-Kit (median: 46.7 s, range 37.0-67.3 s) were used. A significantly faster airway was established using the non-cuffed devices TracheoQuick (median: 20.2 s, range 11.4-44.7 s), Airfree (median: 22.8 s, range 14.3-33.2 s), Quicktrach I (median: 21.1 s, range 14.5-32.4 s) and the peripheral intravenous cannula (median: 19.2 s, range 10.8-27.8 s). Incorrect tube placements were not observed.

Conclusion: This study allowed the comparison of surgical coniotomy to several ready-to-use devices in a standardized setting utilizing a reusable plastic mannequin. The interpretation for real emergency conditions is limited as individual anatomy, traumatic alterations of the neck or complications, such as bleeding or damage of important structures were not part of the study objectives. However, all participating emergency physicians successfully used the coniotomy sets provided at the first attempt. No device required significantly more time than the surgical approach. The procedures using cuffed devices lasted longer in comparison to procedures using uncuffed ones; however, this difference would only play a minor role in reality as effective ventilation with minute volumes greater than 7 l/min will only be achieved by a cuffed cannula with a minimum internal diameter of 4 mm. Devices with no cuff or with tube diameters smaller than 4 mm will only allow oxygenation of the patient, which in turn requires an inspiratory oxygen concentration of 100% and a relatively high ventilation frequency.