Cardiovascular regulation of bedridden patients with severe physical disabilities to orthostatic stress and lower body negative pressure

The purpose of this investigation was to identify the cardiovascular response to an orthostatic tolerance test in severely disabled patients during prolonged recumbency in a sitting position and under lower body negative pressure. The disabled subjects were categorized into three groups according to the degree of their exposure to gravitational stress in daily living and their past history of posture and motor ability. The members of one group (ST1) were now supported in a sitting position during present daily living and were able to sit or stand independently in the past. The subjects in the second group (ST2) were never able to sit or stand independently but were also supported in an orthostatic posture during daily living as were ST1 group members. The third group (BR) was bedridden fully from birth and had no experience, ever, of orthostatic forces during daily living. A marked decrease in photoplethysmogram of the big toe in the change from the resting supine to the sitting condition, which represent...