Supine vs. elevated supine postures: Comparative effects on blood ejection and perfusion

The comparative effects on blood ejection and perfusion between supine and elevated supine postures with upper body elevations were investigated in this study. Blood ejection and perfusion were measured by electrical bioimpedance and laser Doppler flowmetry techniques respectively in normal human subjects. Using hardware and software, electrical bioimpedance based blood ejection from heart were calculated in different supine postures (normal and elevated). Skin blood perfusions were also measured by laser Doppler flowmetry technique in all cases. At first, data recordings were performed in normal supine posture (upper body elevated by 0
^o
). Data recordings were done also when upper body elevations were sequentially increased to 15
^o
, 30
^o
, and 45
^o
. Changes in Blood ejection and perfusion were significant when upper body elevations were increased to a higher angle. Results showed highest blood ejection and perfusion in normal supine posture or elevated supine posture (30° elevation only) for most of the subjects. Optimum blood ejection and perfusion are desirable for better performance in blood circulation as well as to meet body's metabolic needs. It is recommended highly to sleep in supine posture with no elevation or 30° elevated supine posture only if the subject prefers to sleep in some elevation.