Inspiratory Resistance, Cerebral Blood Flow Velocity, and Symptoms of Acute Hypotension
Abstract
Introduction: Symptoms of orthostatic intolerance, e.g., following prolonged bed rest and microgravity exposure, are associated with reductions in cerebral blood flow. We tested the hypothesis that spontaneously breathing through an impedance threshold device (ITD) would attenuate the fall in cerebral blood flow velocity (CBFV) during a hypotensive ortho- static challenge and reduce the severity of reported symptoms. Methods: While breathing through either an active ITD ( - 7 cm H2O inspiratory impedance) or a sham ITD (no impedance), 19 subjects performed a squat stand test (SST). Symptoms upon stand were recorded on a 5-point scale (1 = normal; 5 = faint) of subject-perceived rating (SPR). To address our hypothesis, only data from symptomatic subjects (SPR greater than 1 during the sham trial) were analyzed ( N = 9). Mean arterial blood pressure (MAP) and mean CBFV were measured continuously throughout the SST and analyzed in time and frequency domain.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 2008
- Accession Number
- ADA630425
Entities
People
- Caroline A Rickards
- Christopher T Lee
- Don F. Doerr
- Kathy L. Ryan
- Keith G. Lurie
- Kenneth D. Cohen
- Lindsey L. Bergeron
- Lubrina Burton
- Prateek J. Khatri
- William H. Cooke
Organizations
- United States Army Institute of Surgical Research