Key result
Antiorthostatic posture change decreased mean arterial pressure both with (98 to 90 mmHg, P<0.005) and without (94 to 84 mmHg, P<0.0001) total arterial thigh occlusion.
Why the study?
Does total arterial thigh occlusion prevent the hypotensive effects of an antiorthostatic posture change in healthy males?
Does total arterial thigh occlusion prevent the hypotensive effects of an antiorthostatic posture change in healthy males?
p-value: p=<0.005
Vasodilatation in the legs is not necessary for the hypotensive effects of a moderate antiorthostatic posture change, pointing to central vascular beds as the primary mechanism.
Leg vasodilatation unnecessary for postural MAP reduction in healthy adults; leaves open mechanisms and relevance to clinical orthostatic hypotension.
Previous results from our laboratory have shown that vasodilatation in the legs prevents mean arterial pressure (MAP) from increasing during water immersion. Therefore, we tested the hypothesis that vasodilatation in the legs is necessary for the hypotensive effects to occur during a moderate antiorthostatic posture change. 2. Ten healthy males underwent a 5 min posture change from upright seated to horizontal supine (SUP) and back to seated again with (OCCL-SUP) and without simultaneous total arterial (154 +/- 1 mmHg) thigh occlusion, and a control seated period, also with and without arterial occlusion. Cardiac output (CO) was measured by a non-invasive foreign (N2O) gas rebreathing technique. 3. MAP (brachial auscultation) decreased during SUP from 94 +/- 3 to 84 +/- 2 mmHg (P < 0.0001) and total peripheral vascular resistance (TPR = MAP/CO, n = 8) decreased by 15 +/- 4 % (P < 0.001). During OCCL-SUP, MAP decreased from 98 +/- 2 to 90 +/- 2 mmHg (P < 0.005) and TPR decreased by 14 +/- 3 % (P < 0.01). 4. In conclusion, vasodilatation in the legs is not necessary for the decrease in MAP to occur during a moderate antiorthostatic manoeuvre. Therefore, vasodilatation in more central vascular beds (e.g. abdomen) can alone account for the hypotensive effects.
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Pump et al. (1999) studied Healthy (n=10). Antiorthostatic posture change with total arterial thigh occlusion vs. Antiorthostatic posture change without occlusion was evaluated on Mean arterial pressure (MAP) (p=<0.005). Antiorthostatic posture change decreased mean arterial pressure both with (98 to 90 mmHg, P<0.005) and without (94 to 84 mmHg, P<0.0001) total arterial thigh occlusion.
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