Gamble J, Baranov V, Kotov A, Gartside I, Nehring I, Christ F
Department of Physiology, Charing Cross and Westminster Medical School, London, Great Britain.
J Gravit Physiol. 1997 Jul;4(2):P35-6.
Tilt procedures are frequently used to test central and peripheral cardio-vascular reflexes. We have previously used venous congestion strain gauge plethysmography for measurement of fluid filtration capacity (Kf) in human legs and have shown that, providing small cumulative venous congestion pressure steps are applied, venous congestion pressure can be increased to arterial diastolic pressure without activating peripheral vasoconstrictor mechanisms. We have also studied the effect of passive tilting on Kf and have shown that the procedure does not influence the measured value Kf indicating that passive tilting does not after the total surface area available for fluid filtration, but rather the blood flow in the microvessels of the tissue under study. In the present protocol we compared the fluid filtration (Jv) resulting from small (7-10 mmHg) cumulative pressure steps with those obtained by altering hydrostatic load with progressive increases and decreases of head down tilt of -8 degrees -15 degrees and -30 degrees, followed by a similar pattern of 15 degrees, 30 degrees and 70 degrees of head up tilt. The values of Jv obtained in response to these procedures were compared with those deduced from the relationship between fluid filtration and venous congestion pressure (Pcuff) obtained during the small cumulative pressure step protocol. It was reasoned that reflex activation, by the tilt induced pressure load, would cause a reduction in local blood flow and enhanced microvascular fluid extraction. The resulting local increase in colloid osmotic pressure would give rise to lower values of Jv than those predicted on the basis of the Kf slope.
倾斜试验常用于测试中枢和外周心血管反射。我们之前使用静脉充血应变片体积描记法测量人腿部的液体滤过能力（Kf），并且已经表明，如果施加小的累积静脉充血压力步长，静脉充血压力可以增加到动脉舒张压而不激活外周血管收缩机制。我们还研究了被动倾斜对Kf的影响，并且已经表明该过程不影响测量值Kf，这表明被动倾斜不会改变可用于液体滤过的总表面积，而是改变所研究组织微血管中的血流。在本方案中，我们将小（7 - 10 mmHg）累积压力步长产生的液体滤过（Jv）与通过将头向下倾斜-8度、-15度和-30度并逐渐增加和减少静水负荷，随后以15度、30度和70度头向上倾斜的类似模式获得的液体滤过进行比较。将响应这些过程获得的Jv值与从小累积压力步长方案期间获得的液体滤过与静脉充血压力（袖带压力）之间的关系推导得出的值进行比较。据推测，倾斜诱导的压力负荷引起的反射激活将导致局部血流减少和微血管液体提取增加。由此产生的局部胶体渗透压升高将导致Jv值低于基于Kf斜率预测的值。
