Menegazzi J J, Winslow H J
Center for Emergency Medicine of Western Pennsylvania, Pittsburgh 15213, USA.
Acad Emerg Med. 1994 Jan-Feb;1(1):29-33. doi: 10.1111/j.1553-2712.1994.tb02797.x.
To determine whether tidal volume, intrapleural pressure, and gastric volume differ when the bag--valve-- mask (BVM) and the manually triggered oxygen powered breathing device (MTBD) are used in the settings of normal and decreased lung compliance.
Prospective, randomized in-vitro model, with emergency medical technician-paramedics (EMT-Ps; n = 10) and emergency medical technicians (EMTs; n = 20) blinded to model gauges. Each participant randomly performed four one-minute trials ventilating a mechanical test lung through an intubation mannikin head at a rate of 20 breaths/min. Each subject used the BVM and the MTBD to ventilate the lung for 20 breaths during normal (0.10 L/cm H2O) and decreased 0.04 L/cm H2O) compliance. Tidal volumes and intrapleural pressures were recorded for every breath and the gastric volume was recorded for each trial using a flowmeter placed below a simulated esophageal sphincter (20 cm H2O PEEP valve).
With normal compliance, mean tidal volumes and intrapleural pressures were not significantly different, while mean gastric volumes differed significantly (BVM = 1,300 mL, MTBD = 0 mL; p < 0.001). When compliance was decreased, mean tidal volumes and intrapleural pressures again did not differ significantly, while gastric volumes remained significantly different (BVM = 3,700 mL, MTBD = 1,100 mL p < 0.001).
In this model, tidal volumes and intrapleural pressures were similar for the two devices. When compliance was normal, no participant insufflated the stomach with the MTBD, while the gastric volume with BVM ventilation averaged 1.3 L. With decreased compliance, the MTBD again delivered significantly less gastric volume than the BVM (1.1 vs. 3.7 L, respectively). These findings favoring MTBD ventilation require corroboration in vivo.
确定在正常肺顺应性和降低的肺顺应性情况下，使用袋阀面罩（BVM）和手动触发的氧气驱动呼吸装置（MTBD）时潮气量、胸腔内压和胃内气体量是否存在差异。
前瞻性随机体外模型，急诊医疗技术人员-护理人员（EMT-P；n = 10）和急诊医疗技术人员（EMT；n = 20）对模型测量值不知情。每位参与者以20次/分钟的频率通过插管人体模型头部对机械测试肺进行四次一分钟的通气试验。每位受试者在正常顺应性（0.10 L/cm H₂O）和降低的顺应性（0.04 L/cm H₂O）情况下，使用BVM和MTBD对肺进行20次呼吸通气。记录每次呼吸的潮气量和胸腔内压，并使用置于模拟食管括约肌下方（20 cm H₂O呼气末正压阀）的流量计记录每次试验的胃内气体量。
在正常顺应性时，平均潮气量和胸腔内压无显著差异，而平均胃内气体量有显著差异（BVM = 1300 mL，MTBD = 0 mL；p < 0.001）。当顺应性降低时，平均潮气量和胸腔内压再次无显著差异，而胃内气体量仍有显著差异（BVM = 3700 mL，MTBD = 1100 mL，p < 0.001）。
在该模型中，两种装置的潮气量和胸腔内压相似。当顺应性正常时，没有参与者使用MTBD使胃充气，而使用BVM通气时胃内气体量平均为1.3 L。当顺应性降低时，MTBD导致的胃内气体量再次显著少于BVM（分别为1.1 L和3.7 L）。这些支持MTBD通气的发现需要在体内得到证实。
