Evaluation of Cardiac Function in Humans Wearing Combat Edge or the Tactical Life Support System when Exposed to +Gz-Acceleration.

摘要

Current and future high performance aircraft operate in an envelope which requires both high altitude and acceleration protection for their aircrew. Such protection includes both positive pressure breathing (PPB) and an anti-G suit. These factors have been incorporated into a variety of different aircrew clothing ensemble concepts. As part of an ongoing US Navy evaluation of these integrated life support ensembles, 7 subjects (6 male) were exposed to acceleration stress in the Naval Air Warfare Center Aircraft Division Warminster human centrifuge while wearing the Combined Advanced Technology Enhanced Design G Ensemble (COMBAT EDGE - CE) or the Tactical Life Support System (TLSS). The following report describes how cardiac function, as measured using impedance cardiography, was effected under +Gz-stress while subjects wore these ensembles. It was found that relaxed rapid onset +Gz-tolerance (without anti-G straining maneuvers) was about 1.5 G higher when the subjects wore TLSS as compared to CE. Stroke (SI) and (CI) indices both decreased and heart rate rose as +Gz-stress was increased regardless of the outfit worn. While the absolute values of these indices were somewhat higher when CE was worn, the relative change in SI and Cl (Delta SI, Delta CI,) with respect to pre-stress values was smaller with the TLSS ensemble. For both garments, Delta SI and Delta CI was greatest at +6 Gz (PBG = 24 mmhg). However, TLSS, Delta SI and Delta CI were markedly reduced with PBG levels > 30 mmHg (+6.5 Gz). Impedance cardiography, Stroke volume, G-Protection, Combat edge, TLSS.