Jardin F, Farcot J C, Guéret P, Prost J F, Ozier Y, Bourdarias J P
J Appl Physiol Respir Environ Exerc Physiol. 1984 Mar;56(3):619-27. doi: 10.1152/jappl.1984.56.3.619.
Using M-mode and two-dimensional echocardiography, we have compared left and right ventricular dimensions at expiration and inspiration in a group of 12 healthy young volunteers during the following two distinct periods: 1) a control period with atmospheric pressure breathing, and 2) a continuous positive airway pressure (CPAP) period with 15 cmH2O end-expiratory pressure breathing. In 6 of the 12 subjects we also evaluated inferior vena caval size, using the same technique. Inspiratory decrease in left ventricular short-axis area (A), length (L), calculated volumes (V = 5/6 AL), and inspiratory increase in right ventricular short-axis diameter and long-axis area were evident at both control and CPAP periods. CPAP also produced a marked decrease in left and an increase in right ventricular dimensions during both expiration and inspiration and a significant decrease in calculated stroke output. An increase in vena caval size during CPAP breathing indirectly suggested a decrease in venous return, but the finding of an unchanged percent of inspiratory change of this vessel during CPAP indicated that the inspiratory augmentation of venous return was still present. On the other hand, the finding of an increased right ventricular size indicated that the right ventricle was afterloaded by CPAP; this probably could explain the observed reduction in calculated stroke output.
我们使用M型和二维超声心动图，在以下两个不同时期，对12名健康年轻志愿者在呼气和吸气时的左、右心室尺寸进行了比较：1）大气压呼吸的对照期，以及2）呼气末压力为15 cmH₂O的持续气道正压通气（CPAP）期。在12名受试者中的6名中，我们还使用相同技术评估了下腔静脉大小。在对照期和CPAP期，吸气时左心室短轴面积（A）、长度（L）、计算得出的容积（V = 5/6AL）减小，以及右心室短轴直径和长轴面积增加均很明显。CPAP在呼气和吸气期间还导致左心室尺寸显著减小，右心室尺寸增加，并且计算得出的每搏输出量显著降低。CPAP呼吸期间腔静脉大小增加间接提示静脉回流减少，但CPAP期间该血管吸气变化百分比未变这一发现表明，静脉回流的吸气增强仍然存在。另一方面，右心室尺寸增加的发现表明右心室因CPAP而承受后负荷增加；这可能可以解释观察到的计算得出的每搏输出量降低。
