Molénat Florence, Boussuges Alain, Grandfond Aliocha, Rostain Jean-Claude, Sainty Jean-Marie, Robinet Claude, Galland François, Meliet Jean Louis
Service de Réanimation Médico-Chirurgicale et de Surveillance Continue, Centre Hospitalier du pays d'Aix, Aix en Provence, France.
Clin Sci (Lond). 2004 Apr;106(4):389-95. doi: 10.1042/CS20030293.
In the present study, we observed the haemodynamic changes, using echocardiography and Doppler, in ten healthy volunteers during 6 h of compression in a hyperbaric chamber with a protocol designed to reproduce the conditions as near as possible to a real dive. Ambient pressure varied from 1.6 to 3 atm (1 atm=101.325 kPa) and partial pressure of inspired O2 from 1.2 to 2.8 atm. Subjects performed periods of exercise with breathing through a closed-circuit self-contained underwater breathing apparatus (SCUBA). Subjects did not eat or drink during the study. Examinations were performed after 15 min and 5 h. After 15 min, stroke volume (SV), left atrial (LA) diameter and left ventricular (LV) end-diastolic diameter (LVEDD) decreased. Heart rate (HR) and cardiac output (CO) did not vary, but indices of the LV systolic performance decreased by 10% and the LV meridional wall stress increased by 17%. After 5 h, although weight decreased, the serum protein concentration increased. Compared with values obtained after 15 min, SV and CO decreased, but LV systolic performance, LA diameter, LVEDD and LV meridional wall stress remained unchanged. Compared with the reference values obtained at sea level, total arterial compliance decreased, HR remained unchanged and CO decreased. In conclusion, hyperbaric hyperoxia results in significant haemodynamic changes. Initially, hyperoxia and the SCUBA system are responsible for reducing LV preload, increasing LV afterload and decreasing LV systolic performance, although CO did not change. Prolonged exposure resulted in a further decrease in LV preload, because of dehydration, and in a further increase in LV afterload, due to systemic vasoconstriction, with the consequence of decreasing CO.
在本研究中，我们使用超声心动图和多普勒技术，观察了10名健康志愿者在高压舱内6小时的加压过程中的血流动力学变化，所采用的方案旨在尽可能重现实际潜水的条件。环境压力从1.6个大气压变化到3个大气压（1个大气压 = 101.325千帕），吸入氧气的分压从1.2个大气压变化到2.8个大气压。受试者通过闭路自持式水下呼吸器（SCUBA）进行呼吸并进行运动阶段。受试者在研究期间未进食或饮水。在15分钟和5小时后进行检查。15分钟后，每搏输出量（SV）、左心房（LA）直径和左心室（LV）舒张末期直径（LVEDD）减小。心率（HR）和心输出量（CO）没有变化，但左心室收缩功能指标下降了10%，左心室子午线壁应力增加了17%。5小时后，尽管体重减轻，但血清蛋白浓度增加。与15分钟后获得的值相比，SV和CO下降，但左心室收缩功能、LA直径、LVEDD和左心室子午线壁应力保持不变。与海平面获得的参考值相比，总动脉顺应性下降，HR保持不变，CO下降。总之，高压高氧导致显著的血流动力学变化。最初，高氧和SCUBA系统导致左心室前负荷降低、左心室后负荷增加以及左心室收缩功能下降，尽管CO没有变化。长时间暴露由于脱水导致左心室前负荷进一步降低，并且由于全身血管收缩导致左心室后负荷进一步增加，结果是CO下降。
