允许性高碳酸血症治疗ARDS中肺力学及血流动力学变化

Therapeutic Effects of Permissive Hypercapnia on Pulmonary Mechanics and Hemodynamics in Patients with Acute Respiratory Distress Syndrome

目的探讨允许性高碳酸血症（permissive hypercapnia，PHC）对重度急性呼吸窘迫综合征（acute respiratory distress syndrome，ARDS）肺力学及血流动力学的影响。方法观察不同潮气量（tide volume，VT）时，20例重度ARDS惠者肺气体交换、肺力学和血流动力学的改变。结果当VT从15ml／kg降至6ml／kg时，患者均出现PHC，动脉血氧分压、氧饱和度和混合静脉血氧饱和度显著降低（P〈0．05）。PHC时，气道压力显著降低，气道阻力明显增高（P〈0．05）；左心室做功指数、心率、血压和心排指数等无明显变化。静态肺压力一容积曲线高位转折点对应的压力为（22．2±1．8）cm H2O，容积为10ml／kg，1cmH2O=0．098kPa。结论在实施PHC时，只有当气道平台压〈20-25cmH2O时才有可能避免肺泡过度膨胀，且实施PHC时血流动力学无明显变化。

Objective To explore the therapeutic effects of permissive hypercapnia （PHC） on pulmonary mechanics and hemodynamics in patients with acute respiratory distress syndrome. Methods Twenty patients with ARDS were admitted in the study. Gas changes, pulmonary mechanics and hemodynamics were observed at different tide volume （VT）. Results When VT decreased from 15 ml/kg to 6 ml/kg, PHC was induced. Arterial oxygen pressure, oxygen saturation and mixed venous oxygen saturation decreased markedly （ P 〈 0.05）. Pressure of airway decreased markedly, but resistance of airway increased （P〈0.05）. But there was no difference in left ventricular stroke work index, heart rate and cardiac index in the groups. In static pressure-volume curve, the pressure of upper inflection point was 22.2 ± 1.8 cmH2O, volume was 10 ml/kg. Conclusion Alveolar overdistension may be prevented only when airway plateau pressure is less than 20-25 cm H2O, and no hemodynamic changes in PHC.