In order to determine mechanisms for increased stroke volume at birth, left ventricular function was investigated in eight fetal lambs during in utero pulmonary ventilation. At surgery fetuses were prepared with a tracheal tube, aortic electromagnetic flow sensor, and carotid, jugular, pericardial and left atrial catheters. 2. After 8.3 +/- 1.5 (mean +/- S.D.) post-surgery days and at 137 +/- 3 days gestation, haemodynamic values were obtained before and during pulmonary ventilation in utero. 3. During ventilation, O2 content increased from 7.3 +/- 2.1 to 14.7 +/- 2.7 ml dl-1 (P less than 0.001), right atrial pressure from 3.0 +/- 1.3 to 4.5 +/- 1.6 mmHg (P less than 0.05), left atrial pressure from 2.5 +/- 1.2 to 10.2 +/- 3.7 mmHg (P less than 0.001), left ventricular stroke volume from 1.1 +/- 0.4 to 1.9 +/- 1.2 ml kg-1 (P less than 0.05), and heart rate from 160 +/- 21 to 183 +/- 11 beats min-1 (P less than 0.05). 4. During O2 ventilation, left ventricular function curves relating stroke volume to left atrial pressure were shifted upward. 5. O2 ventilation produced rapid, reversible increases in left ventricular stroke volume which approximate increases in stroke volume at birth.
摘要
为了确定出生时每搏输出量增加的机制，在子宫内肺通气期间对8只胎羊的左心室功能进行了研究。手术时，给胎儿准备了气管导管、主动脉电磁流量传感器以及颈动脉、颈静脉、心包和左心房导管。2. 术后8.3±1.5（平均值±标准差）天且妊娠137±3天时，在子宫内肺通气前和通气期间获取血流动力学值。3. 通气期间，氧含量从7.3±2.1增加至14.7±2.7 ml dl-1（P<0.001），右心房压力从3.0±1.3升至4.5±1.6 mmHg（P<0.05），左心房压力从2.5±1.2升至10.2±3.7 mmHg（P<0.001），左心室每搏输出量从1.1±0.4增加至1.9±1.2 ml kg-1（P<0.05），心率从160±21次/分钟增至183±11次/分钟（P<0.05）。4. 在氧气通气期间，将每搏输出量与左心房压力相关联的左心室功能曲线向上移动。5. 氧气通气使左心室每搏输出量迅速、可逆地增加，这与出生时每搏输出量的增加情况相近。
