Pulmonary pressure-flow relationships in the fetal lamb during in utero ventilation.
Pulmonary pressure-flow relationships in the fetal lamb during in utero ventilation.
复制标题
子宫内通气期间胎儿羔羊的肺压力-流量关系。
DOI：
10.1152/jappl.1990.69.5.1630
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发表时间：
1990
期刊：
影响因子：
--
通讯作者：
Thornburg,KL
中科院分区：
文献类型：
--
作者：
Reid,DL;Thornburg,KL
在未分娩的胎羊中，呼吸机肺中的压力-流量关系以前还没有被确定。因此，我们以11只妊娠晚期慢性制备的胎羊为研究对象，采用不同的混合气体进行正压通气，以确定机械扩张和血气张力对肺内压力-流量关系的影响。在动脉血气没有改变的情况下，3%O2-7%CO2的通气会显著降低肺血管阻力。在机械扩张期间，肺血管阻力下降超过机械扩张时，肺动脉血氧分压的增加与肺血管阻力的下降有关。肺动脉二氧化碳分压的降低和相关的pH升高也与肺血管阻力的下降有关。当肺动脉压力超过左房压力时，肺血流停止，这表明左房压力并不代表通过肺血管床的驱动压力的真正下游分量。因此，正常成熟胎羊的驱动力压力-流量关系的斜率不同于肺动脉压/肺动脉流量的比率。结论：机械通气、氧分压升高、二氧化碳分压降低和/或pH升高对胎羊宫内正压通气引起的肺血管阻力下降有重要影响，肺血流下行驱动压大于左房压。
Pressure-flow relationships in the ventilated lung have not been previously determined in undelivered fetal sheep. Therefore we studied 11 late-gestation chronically prepared fetal sheep during positive-pressure ventilation with different gas mixtures to determine the roles of mechanical distension and blood gas tensions on pressure-flow relationships in the lung. Ventilation with 3% O2-7% CO2 produced a substantial fall in pulmonary vascular resistance even though arterial blood gases were not changed. Increases in pulmonary arterial PO2 during ventilation were associated with falls in pulmonary vascular resistance beyond that measured during mechanical distension. Decreases in pulmonary arterial PCO2 and associated increases in pH were also associated with falls in pulmonary vascular resistance. Pulmonary blood flow ceased at a pulmonary arterial pressure that exceeded left atrial pressure, indicating that left atrial pressure does not represent the true downstream component of driving pressure through the pulmonary vascular bed. The slope of the driving pressure-flow relationship in the normal mature fetal lamb was therefore different from the ratio of pulmonary arterial pressure to pulmonary arterial flow. We conclude that mechanical ventilation, increased PO2 and decreased PCO2, and/or increased pH has an important influence on the fall in pulmonary vascular resistance elicited by positive pressure in utero ventilation of the fetal lamb and that the downstream driving pressure for pulmonary blood flow exceeds left atrial pressure.