Key result
High-pressure blood flow restriction mitigates orthostatic systolic blood pressure drop by ~5.5 mmHg vs sham.
Why the study?
Orthostatic intolerance occurs in some astronauts after space flight, creating a need for an immediate short-term solution to maintain blood pressure during situations like emergency evacuation.
Does blood flow restriction maintain blood pressure upon head-up tilt in healthy individuals?
RCT (n=89)
Single-blind (blindly presented to participant)
Blocking method (men and women) counterbalancing the three different pressures
No
Does blood flow restriction maintain blood pressure upon head-up tilt in healthy individuals?
Applying lower-body blood flow restriction mitigates the orthostatic decline in blood pressure upon head-up tilt, suggesting a potential short-term countermeasure for orthostatic intolerance.
Answers are grounded in this paper and cite their sources.
May support blood flow restriction as a short-term orthostatic countermeasure; first RCT evidence leaves efficacy in patients open.
Background: Orthostatic intolerance occurs in some astronauts following space flight. Although orthostatic blood pressure responses should normalize in the weeks following the return to Earth, there may be situations where an immediate short-term solution is necessary (e.g., emergency evacuation). Purpose: The purpose of this study was to examine different levels of blood flow restriction on changes in blood pressure and heart rate when transitioning from supine to a head-up tilt and determine whether this change differs based on sex. Methods: Eighty-nine participants (45 men, 44 women) completed the three visits with different pressures (Sham, Moderate, and High) in a randomized order. Cuffs were placed on the most proximal area of the thighs. Brachial blood pressure was measured at baseline, upon inflation of the cuffs in a supine position, immediately after tilt (70°), and eight more times separated by 45 seconds. Results: Data are presented as mean (SD). The change in systolic (High > Moderate > Sham) [High vs Sham: 5.5 (7.4) mmHg, High vs Moderate: 3 (7.4) mmHg, and Moderate vs Sham: 2.4 (8.4) mmHg] and diastolic pressure (High > Moderate = Sham) [High vs Sham: 2.4 (5.3) mmHg, High vs Moderate: 1.9 (6.3) mmHg] differed across applied pressures. The change in heart rate was initially greatest in the sham-pressure but increased the greatest in the high-pressure condition by the end of the head-up tilt period. Additionally, there was no influence of sex. Conclusion: Blood flow restriction applied in this study increased blood pressure in a pressure-dependent manner upon head-up tilt.
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Wong et al. (2022) conducted an RCT in Healthy individuals (Orthostatic intolerance model) (n=89). Blood flow restriction vs. Sham pressure (0 mmHg) was evaluated on Change in systolic blood pressure transitioning from supine to head-up tilt (Mean difference 5.5 mmHg (SD 7.4) for High vs Sham, p=<0.05). High-pressure blood flow restriction mitigated the orthostatic drop in systolic blood pressure compared to sham, with a mean difference of 5.5 mmHg.
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