Bassell G M, Humayun S G, Marx G F
Obstet Gynecol. 1980 Jul;56(1):39-41.
A prospective study of 12 unmedicated pregnant women in the second stage of labor was undertaken to assess the effects of bearing down efforts on brachial and popliteal blood pressure. Inferior vena cava compression, usually detected by reductions in mean and/or pulse pressure in the brachial artery, did not occur at any time, whether or not the uterus was displaced to the left. Abdominal aortic compression, suggested by popliteal pressure fall, was maintained into the second stage of labor, was aggravated when the women bore down, and was alleviated only when bearing down efforts ceased and the uterus was displaced to the left. Bearing down efforts are therefore yet another mechanism by which distal aortic and possibly uteroplacental blood flow can be prejudiced. Their avoidance can be advantageous to the fetus at risk.
对12名处于第二产程且未用药的孕妇进行了一项前瞻性研究，以评估屏气用力对肱动脉和腘动脉血压的影响。下腔静脉受压通常通过肱动脉平均压和/或脉压降低来检测，无论子宫是否向左移位，在任何时候都未发生。腘动脉压力下降提示腹主动脉受压，这种情况在第二产程持续存在，妇女屏气用力时加重，只有在屏气用力停止且子宫向左移位时才缓解。因此，屏气用力是另一种可能损害远端主动脉及子宫胎盘血流的机制。避免屏气用力对处于危险中的胎儿可能有益。
