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Hemodynamics in diabetic orthostatic hypotension
The Journal of Clinical Investigation
|December 1, 1981
Summary
Diabetic hypoadrenergic orthostatic hypotension is characterized by an impaired ability to increase vascular resistance, likely due to reduced sympathetic activity. This leads to significant blood pressure drops upon standing in affected patients.
Area of Science:
- Cardiovascular Physiology
- Diabetology
- Autonomic Nervous System Function
Background:
- Orthostatic hypotension is a common complication in diabetic patients, particularly those with neuropathy.
- The underlying mechanisms of hypoadrenergic orthostatic hypotension in diabetes are not fully understood.
- Autonomic dysfunction affects sympathetic nerve activity, impacting cardiovascular regulation.
Purpose of the Study:
- To investigate hemodynamic and neurohormonal responses to standing in diabetic patients with varying degrees of neuropathy.
- To identify the pathophysiological defects contributing to orthostatic hypotension in diabetes.
- To compare responses between normal subjects and diabetic groups with and without neuropathy.
Main Methods:
- Measured hemodynamic variables (blood pressure, cardiac output, heart rate, plasma volume, splanchnic and peripheral blood flow) in supine and standing positions.
- Assessed plasma concentrations of norepinephrine, epinephrine, and renin.
- Compared responses in normal subjects and three diabetic groups: no neuropathy, slight neuropathy, and severe neuropathy with orthostatic hypotension.
Main Results:
- Diabetic patients with orthostatic hypotension showed precipitous blood pressure decreases upon standing.
- Increases in total peripheral, splanchnic, and subcutaneous vascular resistance were significantly lower in patients with orthostatic hypotension.
- Reduced plasma norepinephrine increase upon standing was observed in the orthostatic hypotension group, suggesting impaired sympathetic activity.
Conclusions:
- Diabetic hypoadrenergic orthostatic hypotension is primarily caused by an inability to increase vascular resistance, likely due to impaired sympathetic nerve function.
- Cardiac output and plasma volume responses to standing are comparable in normal subjects and diabetics without neuropathy.
- Findings highlight the role of autonomic neuropathy in the pathogenesis of orthostatic hypotension in diabetes.
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