Modin A Iu, Shashkov V S
Aviakosm Ekolog Med. 1992 Mar-Apr;26(2):26-9.
Fourteen volunteers were exposed to a graded orthostatic test by a passive tilt from the horizontal position (0 degree) to an orthostatic posture (70 degrees) with intermediate angles of 10, 20, 30, 40, 50 and 60 degrees. Each position was maintained for 5 min. At the end of each step ECG, the first derivative of impedance cardiogram and auscultative blood pressure were registered. Stroke volume, cardiac output, Q-Z interval, thoracic impedance and diastole-systolic coefficient of impedance cardiogram (the parameter of pre-loading) were most markedly changed at the beginning of the test, when the tilt angle was less than 30 degrees. Its further increase was associated with moderate changes of the mentioned parameters. Diastolic arterial pressure began growing significantly from the tilt angle of 10 degrees and the cardiac rhythm became significantly more frequent starting from 30 degrees. Thus, the set of parameters registered becomes more informative if the test is performed in a graded manner since in this case it is possible to evaluate the order and magnitude of passive and active hemodynamic changes, and on the basis of their comparison to assess the adequacy of compensatory circulatory responses to orthostatic exposure.
14名志愿者接受了分级直立试验，通过从水平位置（0度）被动倾斜至直立姿势（70度），中间角度为10度、20度、30度、40度、50度和60度。每个姿势保持5分钟。在每一步结束时记录心电图、阻抗心动图的一阶导数和听诊血压。在试验开始时，当倾斜角度小于30度时，每搏输出量、心输出量、Q-Z间期、胸阻抗和阻抗心动图的舒张期-收缩期系数（预负荷参数）变化最为明显。其进一步增加与上述参数的适度变化有关。舒张压从10度倾斜角度开始显著升高，心律从30度开始显著加快。因此，如果以分级方式进行试验，所记录的参数集将更具信息性，因为在这种情况下，可以评估被动和主动血液动力学变化的顺序和幅度，并在比较的基础上评估对直立暴露的代偿性循环反应的充分性。
