Didier Péan

Airtraq laryngoscope for intubation in Treacher Collins syndrome.

Implications. New York: McGraw-Hill, 2006: 87–88. 3 Butler M, Hayes B, Hathaway M et al. Specific genetic diseases at risk for sedation ⁄ anesthesia complications. Anesth Analg 2000; 91: 837–855. 4 Sun D, Warriner C, Parsons D et al. The GlideScope Video Laryngoscope: randomized clinical trial in 200 patients. Br J Anaesth 2005; 94: 381–384. 5 Lai H, Chen I, Chen A et al. The use of the GlideScope for tracheal intubation in patients with ankylosing spondylitis. Br J Anaesth 2006; 97: 419–422.

Oxygen delivery during transtracheal oxygenation: a comparison of two manual devices.

BACKGROUND:The Manujet™ and the ENK Oxygen Flow Modulator™ (ENK) deliver oxygen during transtracheal oxygenation. We sought to describe the ventilation characteristics of these 2 devices. METHODS:The study was conducted in an artificial lung model consisting of a 15-cm ringed tube, simulating the trachea, connected via a flow analyzer and an artificial lung. A 15-gauge transtracheal wire reinforced catheter was used for transtracheal oxygenation. The ENK and Manujet were studied for 3 minutes at respiratory rates of 0, 4, and 12 breaths/min, with and without the artificial lung, in a totally and a partially occluded airway. Statistical analysis was performed using analysis of variance followed by a Fisher exact test; P < 0.05 was considered significant. RESULTS:Gas flow and tidal volume were 3 times greater with the Manujet than the ENK (approximately 37 vs 14 L · min−1 and 700 vs 250 mL, respectively) and were not dependent on the respiratory rate. In the absence of ventilation, the ENK delivered a 0.6 ± 0.1 L · min−1 constant gas flow. In the totally occluded airway, lung pressures increased to 136 cm H2O after 3 insufflations with the Manujet, whereas the ENK, which has a pressure release vent, generated acceptable pressures at a low respiratory rate (4 breaths/min) (peak pressure at 27.7 ± 0.7 and end-expiratory pressure at 18.8 ± 3.8 cm H2O). When used at a respiratory rate of 12 breaths/min, the ENK generated higher pressures (peak pressure at 95.9 ± 21.2 and end-expiratory pressure at 51.4 ± 21.4 cm H2O). In the partially occluded airway, lung pressures were significantly greater with the Manujet compared with the ENK, and pressures increased with the respiratory rate with both devices. Finally, the gas flow and tidal volume generated by the Manujet varied proportionally with the driving pressure. DISCUSSION:This study confirms the absolute necessity of allowing gas exhalation between 2 insufflations and maintaining low respiratory rates during transtracheal oxygenation. In the case of total airway obstruction, the ENK may be less deleterious because it has a pressure release vent. Using a Manujet at lower driving pressures may decrease the risk of barotrauma and allow the safe use of higher respiratory rates.

What is the accuracy of the high-fidelity METI Human Patient Simulator physiological models during oxygen administration and apnea maneuvers?

BACKGROUND: A widely used physiological simulator is generally accepted to give valid predictions of oxygenation status during disturbances in breathing associated with anesthesia. We compared predicted measures with physiological measurements available in the literature, or derived from other models. METHODS: Five studies were selected from the literature which explored arterial oxygenation, with or without preoxygenation, in clinical situations or through mathematical modeling as well as the evolution of the fraction of expired oxygen (FEO2) during preoxygenation maneuvers. Scenarios from these studies were simulated on the METI-Human Patient Simulator™ simulator, and the data were compared with the results in the literature. RESULTS: Crash-induction anesthesia without preoxygenation induces an O2 pulse saturation (SpO2) decrease that is not observed on the METI simulator. In humans, after 8 minutes of apnea, SpO2 decreased below 90% while the worst value was 95% during the simulation. The apnea time to reach 85% was less with obese patients than with healthy simulated patients and was shortened in the absence of preoxygenation. However, the data in the literature include METI simulator confidence interval 95% values only for healthy humans receiving preoxygenation. The decrease in PaO2 during 35-second apnea started at end-expiration was slower on the METI simulator than the values reported in the literature. FEO2 evolution during preoxygenation maneuvers on the METI simulator with various inspired oxygen fractions (100%, 92%, 84%, and 68%) was very close to those reported in humans when perfect mask seal is provided. In practice, this seal is impossible to obtain on the METI simulator. CONCLUSIONS: SpO2 decreased much later during apnea on the METI simulator than in a clinical situation, whether preoxygenation was performed or not. The debriefing after simulation of critical situations or the use of the METI simulator to test a new equipment must consider these results.