过度通气对狗血流动力学的影响

THE INFLUENCE OF HYPERVENTILATION ON HEMODYNAMICS IN DOGS

本文观察１５只正常狗麻醉后于自主呼吸、机械正常通气、机械过度通气及纠正呼吸性碱中毒后４个阶段的血流动力学变化，发现过度通气后ＰＡＰ及ＣＯ显著下降，分别为２．５５１±０．６５０／２．７６５±０．７９１ｋＰａ，Ｐ＜０．０１和２．１３１±０．６３３／２．３２９±０．７８０Ｌ／ｍｉｎ（Ｐ＜０．０５），二者显著相关（ｒ＝０．６１９２，Ｐ＜０．０２）．气道平均压显著增高，表明（１）呼碱可直接影响ＰＡＰ及ＣＯ；（２）ＨＶ使胸内压升高；（３）呼碱时血钙降低，心肌收缩力下降；（４）后负荷增加．建议临床使用ＨＶ治疗肺动脉高压时应防止严重呼碱及胸内压过度增高，并加强血流动力学的监侧。

The changes of hemodynamies were observed on 15 dogs at the time of spontaneous respiration. mechanic normal ventilation, hyperventilation(HV) and HV with normal PaCO2 respectively. We found that pulmonary artery pressure(PAP) decreased(2.551 ± 0.650 vs 2.765 ±0.791 kPa,P<0.001) accompanied by a significant decrcase in cardiac output(CO) after HV(2.1 3 1 ±0.633 vs 2.309 ± 0.780L/min,P<0.05). The reduction of PAP was found to be correlated with decrcase in CO(r=0.6192, P<0.02). The mean pressure of airway increased markedly during HV and HV with norrnal PaCO2. The causes of these changes were:(1) the direct influence of respiratory alkalosis on PAP and CO;(2) the inercase of intrathoracic pressurc during HV;(3)the reduction in ionized calcium and inhibiting myocardial contractility and;(4) the increase of afterload. We suggest that serious respiratory alkalosis and the overhigh of intrathoracic pressure at the same time of treating pulmonary hypertension with HV should be avoided, and that the hemodynamic monitoring should be enhanced.