A comparison of three techniques for cricothyrotomy on a manikin.

BACKGROUND: Cricothyrotomy can either be performed by an "open" cricothyrotomy technique, or by a needle (Seldinger) technique. Clinical uncertainty exists regarding which technique is more effective. We compared three different techniques for cricothyrotomy, performed by anesthesiologists on a manikin. METHODS: The techniques studied include an open surgical technique, the Melker Cricothyrotomy kit (Cook), and the Portex Cricothyroidotomy Kit (Smiths Medical). Participants were randomized to the order they performed each technique. Each procedure was videotaped and the time to first ventilation recorded. The participants completed a 10-point scale following the performance of all techniques to assess the subjective level of difficulty of each technique and to indicate which technique they would prefer in a real clinical CICO scenario. RESULTS: Mean time to ventilation was significantly faster with the surgical cricothyrotomy technique, when compared with both the Portex and Melker techniques (Mean difference: Portex-surgical = 18 s, 95% CI (1, 36) and Melker-surgical = 42 s, 95% CI (31, 54)). The Portex technique was significantly faster than the Melker technique (Melker-Portex = 24 s, 95% CI (11, 37)). Six of the 11 (55%) participants preferred the Melker procedure, four (36%) preferred the surgical procedure, and only one anesthesiologist (9%) preferred the Portex procedure. DISCUSSION: The surgical technique was faster than both the Portex and Melker techniques. The surgical technique was also more successful than the Melker technique. The preferred technique among the participants was the Melker technique, despite being the slowest, least successful, and rated most difficult by participants and observers. This suggests that although the surgical technique may not be preferred by many airway practitioners, it has been shown to be the most likely technique to achieve the primary goal of the procedure: establishing oxygenation and preventing death. IMPLICATION STATEMENT: This research examines three techniques for cricothyrotomy in the "Can't Intubate, Can't Oxygenate" scenario. Our data, as well as data from other studies, suggest that a practice shift towards a surgical technique, and away from needle based techniques, may be warranted.

Effects of ambient temperature on mechanomyography of resting quadriceps muscle.

It has been speculated that resting muscle mechanical activity, also known as minor tremor, microvibration, and thermoregulatory tonus, has evolved to maintain core temperature in homeotherms, and may play a role in nonshivering thermogenesis. This experiment was done to determine whether resting muscle mechanical activity increases with decreasing ambient temperature. We cooled 20 healthy, human, resting, supine subjects from an ambient temperature of 40° to 12 °C over 65 min. Core temperature, midquadriceps mechanomyography, surface electromyography, and oxygen consumption (VO2) were recorded. Resting muscle mechanical and electrical activity in the absence of shivering increased significantly at temperatures below 21.5 °C. Women defended core temperature more effectively than men, and showed increased resting muscle activity earlier than men. Metabolism measured by VO2 correlated with resting muscle mechanical activity (R = 0.65; p = 0.01). Resting muscle mechanical activity may have evolved, in part, to maintain core temperature in the face of mild cooling.