Sprung J, Mackenzie C F, Green M D, O'Dwyer J, Barnas G M
Department of Anesthesiology, Cleveland Clinic Foundation, OH 44195-9247, USA.
J Cardiothorac Vasc Anesth. 1997 Aug;11(5):608-12. doi: 10.1016/s1053-0770(97)90014-8.
In trauma and in surgical patients, respiratory mechanics may change because of many factors, including the hypotension induced by hemorrhage. The effects of acute hemorrhage on elastic and resistive characteristics of the respiratory system were studied.
Prospective study.
Anesthesia research laboratory.
Acute hemorrhagic shock was induced in 24 supine anesthetized/paralyzed, mechanically ventilated dogs by blood withdrawal over a 12-minute period to decrease systolic arterial pressure to 50 mmHg; additional blood was subsequently withdrawn to maintain this pressure for 2 hours. Total respiratory system dynamic compliance and resistance and lung and chest wall compliances and resistances were measured.
Total respiratory system dynamic compliance decreased from control (0.03 +/- 0.002 L/cmH2O) by the first 10 minutes of shock (p < 0.05) and was 9.8 +/- 2% lower than control 2 hours after the induction of shock because of decreases in both lung (9.6 +/- 3%) and chest wall (7.7 +/- 3%) compliances. Total respiratory resistance increased 12.8 +/- 3% from control (3.08 +/- 0.19 cmH2O/L/s) after 2 hours of shock (p < 0.05) because of an increase in chest wall resistance (21.6 +/- 8%, p < 0.05). Pulmonary resistance was not significantly increased (p > 0.05). In six control dogs, prepared similarly but not hemorrhaged, chest wall compliance and resistance did not change, but lung compliance gradually decreased by 17.8% during 150 minutes of anesthesia/paralysis. Lung resistance increased only after 100 minutes (p < 0.05).
(1) Hemorrhagic shock caused slight changes in the chest wall, but effects on lung mechanics were a consequence of prolonged mechanical ventilation during anesthesia/paralysis, and (2) changes in respiratory mechanics caused by hemorrhagic shock are small and, unless other deleterious factors are present, would probably have little clinical significance.
在创伤患者和外科手术患者中，呼吸力学可能因多种因素而改变，包括出血引起的低血压。本研究探讨急性出血对呼吸系统弹性和阻力特性的影响。
前瞻性研究。
麻醉研究实验室。
对24只仰卧位麻醉/瘫痪、机械通气的犬，在12分钟内通过放血诱导急性失血性休克，使收缩压降至50 mmHg；随后再放血以维持该压力2小时。测量全呼吸系统动态顺应性和阻力以及肺和胸壁的顺应性和阻力。
休克最初10分钟内，全呼吸系统动态顺应性较对照组（0.03±0.002 L/cmH₂O）下降（p<0.05），休克诱导2小时后比对照组低9.8±2%，这是由于肺顺应性（9.6±3%）和胸壁顺应性（7.7±3%）均下降所致。休克2小时后，全呼吸阻力较对照组（3.08±0.19 cmH₂O/L/s）增加12.8±3%（p<0.05），原因是胸壁阻力增加（21.6±8%，p<0.05）。肺阻力无显著增加（p>0.05）。在6只同样准备但未出血的对照犬中，胸壁顺应性和阻力未改变，但在麻醉/瘫痪150分钟期间肺顺应性逐渐下降17.8%。肺阻力仅在100分钟后增加（p<0.05）。
（1）失血性休克导致胸壁有轻微变化，但对肺力学的影响是麻醉/瘫痪期间长时间机械通气的结果；（2）失血性休克引起的呼吸力学变化较小，除非存在其他有害因素，可能临床意义不大。
