Orthostatic intolerance (a drop in blood pressure causing faintness upon standing) is often a physiological consequence of spaceflight and can be serious if it impairs an astronauts ability at a time when rapid egress is needed. Dr. Chester A. Rays project will determine whether ultrasonic stimulation of the mastoid (the bone behind the ear) improves orthostatic tolerance and thus could serve as an effective and simple countermeasure for postflight orthostatic intolerance. A secondary goal of this project is to determine the mechanism by which ultrasonic bone stimulation of the mastoid increases orthostatic tolerance.
Overview
Ultrasonic Bone Stimulation: Countermeasure to Orthostatic Intolerance
Principal Investigator:
Chester A. Ray, Ph.D.
Organization:
Pennsylvania State University
Technical Summary
Orthostatic intolerance (OI) is a major physiological consequence of spaceflight. It has been estimated that nearly one-half to two-thirds of all astronauts experience OI after flight. Post-spaceflight OI is a serious medical issue for manned spaceflight because physical performance of an astronaut is severely impaired at a time when rapid egress from the spacecraft may be needed during an emergency. A number of physiological factors have been suggested to contribute to this problem with a number of countermeasures developed to prevent or alleviate post-spaceflight OI. However, as of yet, no single countermeasure has effectively prevented post-spaceflight OI.
The overall objective of this project is to determine whether ultrasonic bone stimulation of the mastoid improves orthostatic tolerance and thus could serve as an effective and simple countermeasure for post-spaceflight OI. Based on preliminary data, it is hypothesized that ultrasonic bone stimulation of the mastoid will improve orthostatic tolerance in OI patients and in subjects exposed to bed rest. A secondary goal of this project is to determine the mechanism by which ultrasonic bone stimulation of the mastoid increases orthostatic tolerance.
It is hypothesized that this novel countermeasure acts to increase sympathetic nerve activity through engagement of the vestibulosympathetic reflex. Direct measurement of muscle sympathetic nerve activity will be made during ultrasonic bone stimulation in young, aged and vestibular deficient subjects. This project should provide clear information on the possible role of ultrasonic bone stimulation of the mastoid as an effective and simple countermeasure for OI following spaceflight.
Earth Applications
The current project may assist in our understanding of the mechanisms responsible for orthostatic intolerance and/or orthostatic hypotension in humans on Earth. Additionally, the device being used to elicit ultrasonic bone stimulation may be developed to help individuals on Earth who experience orthostatic intolerance. This device is noninvasive and poses minimal risk to the patient.
This project's funding ended in 2007