Physiological Effects of Centrifuge-Simulated Suborbital Spaceflight

BACKGROUND: high-G acceleration experienced during launch and re-entry of suborbital spaceflights may present challenges for older or medically susceptible participants. a detailed understanding of the associated physiological responses would support the development of an evidence-based medical approach to commercial suborbital spaceflight.METHODS: there were 24 healthy subjects recruited into 'younger' (18-44 yr), 'intermediate' (45-64 yr) and 'older' (65-80 yr) age groups. cardiovascular and respiratory variables were measured continuously during dynamic combinations of +Gx (chest-to-back) and +Gz (head-to-foot) acceleration that simulated suborbital G profiles for spaceplane and rocket/ capsule platforms. Measurements were conducted breathing air and breathing 15% oxygen to simulate a cabin pressure altitude of 8000 ft.RESULTS: suborbital G profiles generated highly dynamic changes in heart rate, blood pressure, and cardiac output. G-induced hypoxemia was observed, with minimum arterial oxygen saturation < 80% in a quarter of subjects. increased age was associated with greater hypoxemia and reduced cardiac output responses but did not have detrimental cardiovascular effects. ecG changes included recurrent G-induced trigeminy in one individual. Respiratory and visual symptoms were common, with 88% of subjects reporting greyout and 29% reporting blackout. there was one episode of G-induced loss of consciousness (G-lOc).DISCUSSION: suborbital acceleration profiles are generally well tolerated but are not physiologically inconsequential. Marked hemodynamic effects and transient respiratory compromise could interact with predisposing factors to precipitate IP: 8.46.247.10 On: Tue, 27 Dec 2022 10:40:35 adverse cardiopulmonary effects n a minority of participants. Medically susceptible individuals may benefit from Copyright: Aerospace Medical Association expanded preflight centrifuge familiarization that includes targeted physiological evaluation in the form of a Delivered by Ingenta 'G challenge test'.

Automated summary

The study revealed that high-G acceleration during suborbital flights can have significant impacts on cardiovascular and respiratory systems, especially for older or susceptible individuals, leading to hypoxemia and reduced cardiac output. Therefore, developing evidence-based medical approaches for commercial suborbital spaceflights is crucial.