Hyatt R E, Bar-Yishay E, Abel M D
J Appl Physiol (1985). 1985 Jan;58(1):52-7. doi: 10.1152/jappl.1985.58.1.52.
Estimations were made of the vertical gradient of transpulmonary pressure (VGTP) from measurements of esophageal pressure in nine head-up dogs at functional residual capacity (FRC) when alive, when dead, and after total bilateral pneumothorax. The VGTP of 0.4 cmH2O/cm height in the alive state was abolished by pneumothorax, and roentgenograms showed that the heart moved in a caudal-dorsal direction. There was a small but significant increase in the VGTP on going from FRC to near total lung capacity (TLC) in alive head-up dogs. In eight dead head-up dogs heart weight was increased by replacing various amounts of heart blood with Hg. The VGTP was significantly increased from 0.28 to 0.51 cmH2O/cm height. The fractional increase in the VGTP was similar to the fractional increase in heart weight. In five dogs extrapolation to zero heart weight gave an average VGTP of 0.14 cmH2O/cm height. We conclude that the lungs help support the heart in the head-up dog and that the VGTP is in part determined by the pressure distribution required for this support.
通过测量9只处于功能残气量（FRC）的头高位清醒犬、死亡犬以及双侧全气胸后的食管压力，对跨肺压的垂直梯度（VGTP）进行了评估。在清醒状态下，VGTP为0.4 cmH₂O/cm高度，气胸可使其消失，X线片显示心脏向尾背方向移动。在头高位清醒犬从FRC到接近肺总量（TLC）时，VGTP有小幅但显著的增加。在8只头高位死亡犬中，用汞替代不同量的心内血液后，心脏重量增加，VGTP从0.28 cmH₂O/cm高度显著增加至0.51 cmH₂O/cm高度。VGTP的增加分数与心脏重量的增加分数相似。在5只犬中，外推至零心脏重量时，平均VGTP为0.14 cmH₂O/cm高度。我们得出结论，在头高位犬中，肺有助于支撑心脏，并且VGTP部分由这种支撑所需的压力分布决定。
