Prevalence and Etiology of Delayed Orthostatic Hypotension in Adult Women
Presented at the U.S. Food and Drug Administration Science Forum, April 18–20, 2006, Washington, DC, and the Federation of American Societies for Experimental Biology, April 28–May 2, 2007, Washington, DC.
Abstract
Madhavan G, Goddard AA, McLeod KJ. Prevalence and etiology of delayed orthostatic hypotension in adult women.
Objective
To evaluate the contributing roles of venous status, microvascular filtration, and calf muscle pump activity in the etiology of delayed orthostatic hypotension (OH).
Design
Unblinded within-subjects trial.
Setting
Academic clinical research center.
Participants
Convenience sample of healthy adult women (N=30) with an age range of 30 to 65 years.
Intervention
Plantar micromechanical stimulation applied at a 45-Hz frequency and a 50-μm amplitude for a duration of 30 minutes during upright sitting.
Main Outcome Measure
Diastolic blood pressure (DBP).
Results
White women (mean age, 51.8±1.3y) were recruited and screened for delayed OH. About one quarter (9/33) of the screened subjects showed delayed OH as determined by a significant decrease in blood pressure after at least 15 minutes of quiet sitting. Air plethysmographic assessment provided no evidence of venous insufficiency (venous filling index, >2.5mL/s; venous volume, >80mL) or excessive microvascular filtration in the affected subjects, whereas activation of the calf muscle pump (CMP) through plantar-based micromechanical stimulation consistently resulted in a significant increase in systolic blood pressure (SBP) (ΔSBP=22.8±3.9mmHg, P=.003) and DBP (ΔDBP=20.9±3.3mmHg, P=.002).
Conclusions
About 25% of the adult women studied showed delayed OH during quiet sitting and the proximate cause appears to be neuromuscular in origin, specifically inadequate calf muscle tone, because venous and microvascular filtration status is normative in the delayed OH subpopulation and CMP stimulation reverses the hypotension.
Clinical Science and Engineering Research Center and Department of Bioengineering, Innovative Technologies Complex, State University of New York, Binghamton, NY
Reprint requests to Kenneth J. McLeod, PhD, Dept of Bioengineering, Clinical Science and Engineering Research Center, Innovative Technologies Complex, State University of New York, Binghamton, NY 13902-6000
Supported by the New York State Office of Science, Technology, and Academic Research (grant no. NYSTAR C20026) in collaboration with Juvent Medical Inc.
A commercial party having a direct financial interest in the results of the research supporting this article has conferred or will confer a financial benefit on the author or one or more of the authors. McLeod has a financial interest in Juvent Medical Inc, the manufacturer of the plantar stimulation device used in this study.
ABSTRACT