倾斜床模拟推拉动作对心血管功能的影响

目的：探讨倾斜床模拟推拉动作的效果，观察各种体位改变对心血管功能的影响。方法：12名受试者随机分为两组，倒立组在倾斜床上经受“直立位对照（＋1Gz)→倒立位（－1Gz）→直立位（＋1Gz）”；平卧组则经受“直立位对照（＋1Gz）→平卧位（0Gz）→直立位（＋1Gz）”的推拉动作，测定心率（HR）、血压（BP），基础阻抗（Z0），每搏量（SV）、心输出量（CO）及总外周阻力（TPR）等生理指标。结果L在平卧位时，受试者HR减慢，TPR降低，SV和CO增加与直立位比较达显著性水平（P＜0．01）。在倒立位时，上述变化同样出现而且幅度更大，与0Gz比较，－1Gz时HR的降低，SV和CO的增加更为显著，两者比较达到显著性水平，两组各自的再次直立位与直立位间心血管指标变化率的比较，倒立组的多数指标比平卧组的改变程度更大。结论：应用倾斜床模拟推拉动作是可行的，“推”时相不同的G值水平暴露对其后“拉”时相的心血管功能影响程度是不同的。

Effect of tilt-bed simulated push-pull maneuver on cardiovascular function

AIM To explore the effect of push pull maneuver (PPM) simulated by tilt bed on cardiovascular function. METHODS A special tilt bed was used to simulate the push pull maneuver. Twelve healthy male volunteers participated in the experiment and were randomly divided into twogroups. In one group of head down erect position, subjects were kept in head up erect position (+1 Gz) for 1 min (as control), then in head down erect position (-1 Gz) for 30 s and again in head up erect position (+1 Gz) for 1 min. In the other group of head horizontal position, subjects were kept in head up erect position (+1 Gz) for 1 min (as control), then in head horizontal position (0 Gz) for 30 s and again in head up erect position (+1 Gz) for 1 min. The changes of heart rate (HR), blood pressure (BP), basic impedance (Z 0), stroke volume (SV), cardiac output (CO) and total peripheral resistance (TPR) were measured during the experiment. RESULTS As compared with head up erect position, during 0 Gz, HR and TPR decreased significantly ( P <0.01), while SV and CO increased significantly ( P <0.01); during -1 Gz, this trend also appeared and the degree was larger. As compared with 0 Gz, HR during -1 Gz decreased significantly ( P <0.05), while SV and CO increased significantly ( P <0.01). As compared with head up erect position, during again in head up erect position, the changes of above cardiovascular indexes in head down erect group were larger than those in head horizontal group. CONCLUSION Tilt bed can be used to simulate push pull effect; the degree of cardiovascular function at pull time phase is different after being exposed to different acceleration value at push time phase.