Mure M, Glenny R W, Domino K B, Hlastala M P
Departments of Anesthesiology, Medicine, and Physiology and Biophysics, University of Washington, School of Medicine, Seattle, Washington, USA.
Am J Respir Crit Care Med. 1998 Jun;157(6 Pt 1):1785-90. doi: 10.1164/ajrccm.157.6.9711104.
Arterial blood oxygenation in patients with adult respiratory distress syndrome is often improved in the prone position. Critically ill patients often have abdominal distension and whether similar improvements in gas exchange occur with the prone position is not known. We therefore studied the effect of posture on gas exchange in eight ketamine-anesthetized pigs with abdominal distension. A rubber balloon, placed in the abdominal cavity, was filled with water to increase intra-abdominal pressure. The animals were mechanically ventilated with FIO2 = 0.4, and PaCO2 was kept constant. Gas exchange was measured in the supine and prone positions, with and without abdominal distension, in random order, using the multiple inert gas elimination technique (MIGET). When the abdomen was normal, the prone position increased PaO2 by 16 +/- 21 mm Hg (p < 0.05), accompanied by a small, but statistically insignificant, decrease in AaPO2 (p = 0.08) and no change in ventilation/perfusion (V A/Q) heterogeneity measured by MIGET. In the presence of abdominal distension, the prone position increased Pa O2 by 26 +/- 18 mm Hg (p < 0.01) and decreased AaPO2 (p < 0.05) and V A/Q heterogeneity as measured by the log standard deviation of the perfusion distribution (p < 0.01) and the arterial-alveolar difference area (p < 0.05). In addition, intragastric pressure was lower in the prone position (p < 0.01). We conclude that in anesthetized, mechanically ventilated pigs, the prone position improves pulmonary gas exchange to a greater degree in the presence of abdominal distension than when the abdomen is normal.
成人呼吸窘迫综合征患者采取俯卧位时，动脉血氧合情况常常会得到改善。重症患者常伴有腹胀，而俯卧位是否能使气体交换得到类似改善尚不清楚。因此，我们研究了体位对八只患有腹胀的氯胺酮麻醉猪气体交换的影响。在腹腔内放置一个橡胶气球并注满水以增加腹内压。动物采用FIO2 = 0.4进行机械通气，并保持PaCO2恒定。使用多惰性气体排除技术（MIGET），以随机顺序测量仰卧位和俯卧位时、有无腹胀情况下的气体交换情况。当腹部正常时，俯卧位可使PaO2升高16±21 mmHg（p < 0.05），同时AaPO2有小幅下降但无统计学意义（p = 0.08）, 并且通过MIGET测量的通气/灌注（V A/Q）不均一性无变化。存在腹胀时，俯卧位可使Pa O2升高26±18 mmHg（p < 0.01），降低AaPO2（p < 0.05），并使通过灌注分布的对数标准差（p < 0.01）和动脉 - 肺泡差异面积（p < 0.05）测量的V A/Q不均一性降低。此外，俯卧位时胃内压较低（p < 0.01）。我们得出结论，在麻醉、机械通气的猪中，存在腹胀时俯卧位比腹部正常时能更大程度地改善肺气体交换。
