Biomedical subjects

T P Moore

Publications and source records attributed to T P Moore.

5 recordsLinked to original sources

PubMed1992

Changes in leg volume during microgravity simulation.

Little published information exists regarding the magnitude and time course of cephalad fluid shift resulting from microgravity simulations. Six subjects were exposed to 150 min each at horizontal bed rest, 6 degrees head-down tilt, and horizontal water immersion. Fluid shift was estimated by calculating leg volumes from eight serial girth measurements from groin to ankle before, during, and after exposure. Results were compared with data from the first 3 h of spaceflight. By the end of exposure, total leg volume for the six subjects decreased by 2.6 +/- 0.8%, 1.7 +/- 1.2%, and 4.0 +/- 1.6% for horizontal, head-down, and immersion, respectively. Changes had plateaued for horizontal and head-down and had slowed for immersion. Relatively more fluid was lost from the lower leg than the thigh for all three conditions, particularly head-down. During the first 3 h of spaceflight, total leg volume decreased by 8.6%, and relatively more fluid was lost from the thigh than the lower leg. The difference in volume changes in microgravity and simulated microgravity may be caused by the small transverse pressures still present in ground-based simulations and the extremely nonlinear compliance of tissue.

Adult↗

PubMed1987

Clinical characterization and etiology of space motion sickness.

An inflight, clinically-oriented investigation of SMS was begun on STS-4 and revealed the following: compared to motion sickness on Earth, autonomic signs are significantly different in space motion sickness (SMS) vs. motion sickness (MS) in that sweating is not present, pallor or flushing may be present, and vomiting is episodic, sudden, and brief. Nausea may be present but is more often absent. Onset ranges from minutes to hours, plateaus, and rapidly resolves in 8-72 h with 36 h as average. Postflight reactions have been mild unless deliberately provoked in the early period of re-exposure to gravity. Postflight there is a period of resistance to all forms of motion sickness. There is some evidence for individual reduction in sensitivity on repeated flights. Etiology could not be proven objectively; however, the sensitivity to angular motion, often pronounced in pitch, and theoretical considerations make an intravestibular conflict the most likely cause. Electro-oculogram (EOG), audio-evoked potentials, measurement of fluid shifts, and other studies are inconsistent with a transient vestibular hydrops or increased intracranial pressure as a cause.

Electrooculography↗

PubMed1987

Gastrointestinal motility in space motion sickness.

Gastrointestinal (Gl) symptoms in space motion sickness (SMS) are significantly different from those in ordinary motion sickness (MS). Vomiting is sudden, often unexpected, infrequent, never prolonged and usually without nausea. Inflight bowel sounds are absent in those with SMS but present after recovery and in those not affected. Recording and tabulation of sounds was the only technique that could be used as a measure of motility during spaceflight operations. There were 17 subjects, 6 unaffected by SMS, who made ambulatory recordings pre- and inflight. With one exception, all those affected had sharply reduced sounds while those unaffected had increases or moderate reductions. The mechanism of vomiting in SMS appears to be secondary to this ileus in contrast to vomiting in ordinary MS, where the emesis center is thought to be directly triggered by the vestibular system. This ileus appears to be the only consistent and reliable indicator for SMS to date.

Auscultation↗

PubMed1987

Fluid shifts in weightlessness.

Studies of leg volumes in space by multiple girth measurements showed reductions of 1.9 L (12.8% of leg volume) with 1.1 L from the non-dominant leg on Skylab 4. On landing, 65% of postflight leg volume increase was complete at 1.5 h. Measurement of the dominant leg during the equivalent period on Shuttle showed a mean loss of 0.9 L which was 90% complete at 150 min. Postflight increases were 87% complete at 1.5 h postlanding. Mass measurements during and after Skylab 4 showed a loss of 2.5 kg over the first 4 d on-orbit with a gain of 2.7 kg over the first 4 d of recovery. These changes are assumed to be tissue fluids secondary to changes in hydrostatic pressures and are much greater than those seen in bed rest. Rate and magnitude of inflight and postflight changes have significant operational impact.

Arm↗

PubMed1987

Space shuttle inflight and postflight fluid shifts measured by leg volume changes.

This is a study of the inflight and postflight leg volume changes associated with spaceflight on Space Shuttle missions. The results of this study show an inflight volume loss of 2 L from lower extremities, 1 L from each leg, representing an 11.6% volume change. The vast majority of this change appears to be a shift in body fluids, both intravascular and extravascular. The fluid shift occurs rapidly on Mission Day 1 (MD-1), with it being essentially complete by 6 to 10 h. The regional origin of shift and leg volume change shows a far greater absolute volume (708 ml vs. 318 ml) and percentage (69% vs. 31%) of the total change coming from the thigh as compared to the lower leg. Postflight, the return of fluid to the lower extremities occurs rapidly with the majority of volume return complete within 1.5 h postlanding. At 1 week postflight there is a residual leg volume decrement of 283 ml or 3.2% that is probably due to tissue loss secondary to atrophic deconditioning and weight loss.

Body Fluids↗