The Effect of Various Straining Maneuvers on Cardiac Volumes at 1G and During +Gz Acceleration
Abstract
The purpose of this study was to evaluate the effect of Valsalva (Val), isometric contraction (Iso) and the L-1 maneuvers (L-1) on cardiac volumes at IG and during 4G. Two-dimensional echocardiography was used to measure volumes. IG Phase: Eight seated male subjects performed the three maneuvers. The end-diastolic volume (EDV) decreased during Val and L-1 (p< 0.05) . EDV decreased initially but then returned to baseline with Iso. 4G Phase: Seven male subjects experienced three 30 second 4G epochs while performing the three maneuvers. During 4G, 3 of 7 performing Val, 2 of 7 performing Iso, and none performing L-1, experienced peripheral light loss. EDV decreased and stabilized below baseline during the 4Gz epoch (p < 0.05). Heart rate and cardiac output increased for all maneuvers. Differences between the effects of Val, Tso, and L-1 on G-tolerance do not appear to be related to a differential ability to maintain cardiac volumes. L-1 must provide more C protection due to the isometric contraction component of the maneuver and its ability to increase blood pressure.... Echocardiography, Straining maneuver.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 23, 1989
- Accession Number
- ADA262335
Entities
People
- Chuck Goodyear
- David Ratino
- John Seaworth
- Lloyd Tripp
- Lora Howell
- Tom Jennings
Organizations
- Armstrong Laboratory