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Tilt Testing with Combined Lower Body Negative Pressure: a "Gold Standard" for Measuring Orthostatic Tolerance
Published on: March 21, 2013
Sex differences in vasoconstrictor reserve during 70 deg head-up tilt
S S Jarvis1, J P Florian, M J Curren
1Department of Kinesiology, Noll Laboratory, The Pennsylvania State University, University Park, PA 16802, USA.
Experimental Physiology
|September 8, 2009
Summary
Women exhibit lower orthostatic tolerance than men, with a blunted splanchnic vasoconstrictor response during head-up tilt (HUT). This leads to reduced splanchnic blood flow regulation and potentially lower blood pressure in women.
Area of Science:
- Physiology
- Cardiovascular Research
- Sex Differences in Health
Background:
- Orthostatic intolerance is more prevalent in women than men.
- Reduced splanchnic vasoconstriction may contribute to lower orthostatic tolerance in women.
Purpose of the Study:
- To investigate sex differences in splanchnic blood flow and vasoconstriction during head-up tilt (HUT).
- To test the hypothesis that women have a blunted splanchnic vasoconstrictor response during HUT.
Main Methods:
- 14 healthy women and 16 healthy men underwent 70-degree head-up tilt (HUT).
- Measurements included mean arterial blood pressure (MAP), heart rate (HR), cardiac output, stroke volume, splanchnic blood flow (SpBF), and vascular conductance (SVC, SpVC).
- SpBF was assessed using Indocyanine Green clearance.
Main Results:
- Women had lower MAP than men during supine and tilt positions.
- Splanchnic blood flow (SpBF) and splanchnic vascular conductance (SpVC) were lower in women at rest.
- Women showed a blunted decrease in SpVC during HUT compared to men, indicating a reduced vasoconstrictor response.
Conclusions:
- Women tend to have lower tilt-table tolerance.
- A smaller splanchnic vasoconstrictor reserve in women contributes to reduced orthostatic tolerance compared to men.
