What is the clinical evidence from this study?

Study design: Observational. Population: Healthy subjects (n=20). Intervention: Microgravity (0g) vs. Normal gravity (1g). Primary outcome: Central systolic blood pressure (p=0.017).

July 23, 2018Open Access

The Effect of Microgravity on Central Aortic Blood Pressure

Key Result

Transition to microgravity significantly increased central systolic blood pressure from 124 to 127 mm Hg (P=0.017) and augmented cardiac index in healthy subjects.

Study Design

Type

Observational (n=20)

PICO

Population

20 healthy subjects aged 19 to 43 years evaluated during 7 parabolic flights with 22 seconds of weightlessness to assess hemodynamic changes.

Exposure / Comparator

Microgravity (0g) vs Normal gravity (1g)

Primary Outcome

Central systolic blood pressure, p=0.017

Main Result

Absolute Event Rate: 127% vs 124%

p-value: p=0.017

Abstract

BACKGROUND: Blood pressure has been traditionally measured at peripheral arteries. In the past decade, evidence has grown that central aortic blood pressure may be a more powerful predictor for cardiovascular events, but data on its regulation are rare. The present work examines the impact of microgravity on central blood pressure for the first time. METHODS: We performed 7 parabolic flights with 22 seconds of weightlessness in each parabola. Hemodynamic parameters including central systolic blood pressure were measured noninvasively in a free-floating position in 20 healthy subjects (19-43 years of age). RESULTS: Arterial elasticity at rest was normal in all participants (augmentation index 14% (interquartile range (IQR) 10-22), pulse wave velocity 5.2 m/s (IQR 5.0-5.4)). Transition of 1g to 0g led to a significant increase of central systolic blood pressure from 124 (IQR 118-133) to 127 (IQR 119-133) mm Hg (P = 0.017). Cardiac index augmented significantly from 2.5 (IQR 2.2-2.8) to 2.7 (IQR 2.3-3.0) l/min/m2 (P 0.05). CONCLUSION: Whereas there is a multitude of studies on the effects of microgravity on peripheral blood pressure, this study provides first data on central aortic blood pressure. An acute loss of gravity leads to a central blood volume shift with an augmentation of cardiac output. In healthy subjects with normal arterial stiffness, the compensatory decrease of peripheral resistance does not outweigh this effect resulting in an increase of central blood pressure.