Effects of G-Induced Stress on Pulmonary Circulation.
Abstract
These studies evaluated pulmonary circulation under mild gravitational stresses, such as water immersion and passive tilt to the upright position. They extended previous observations that the standard USAF anti-G suit might be more efficient if inflated from below upwards, rather than from the abdominal bladder. A modified anti-G suit was designed with pressure switches that enabled sequential filling from below upward. Utilizing the rebreathing technique previously developed for pulmonary circulatory parameters the authors measured the effects on pulmonary circulatory parameters of water immersion to the neck (NI). They demonstrated that, in the seated subject, such NI caused a significant increase in pulmonary capillary blood flow and diffusing capacity which persisted throughout the 4-hr immersion period. The lack of change in pulmonary tissue volume suggested that the central vascular engorgement so induced is not accompanied by extravasation of fluid into the pulmonary interstitial space. The study thus supports the concept that, in the seated subject, the renal or hormonal effects of NI are mediated by a redistribution of blood volume, with a resultant central hypervolemia.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1976
- Accession Number
- ADA040109
Entities
People
- Adam Wanner
- Marvin A. Sackner
Organizations
- Mount Sinai Medical Center