V A Convertino1, C A Reister. 1. U.S. Army Institute of Surgical Research, Fort Sam Houston, TX 78234-6315, USA.
Abstract
INTRODUCTION: To test the hypothesis that G-suit inflation could increase cardiac chronotropic responses to baroreceptor stimulation and enhance baroreflex buffering of BP, the carotid-cardiac baroreflex response of 12 subjects was measured across two levels of lower body negative pressure (LBNP = 0 and 50 mm Hg) and two levels of G-suit inflation (0 and 50 mm Hg) in random order. METHODS: Carotid-cardiac baroreflex stimulation was delivered via a silastic neck pressure cuff and responsiveness quantified by determination of the maximum slope of the stimulus-response function between R-R intervals (ms) and their respective carotid distending pressures (mmHg). RESULTS: Mean +/- SE baseline control baroreflex responsiveness was 3.8+/-0.4 ms x mm Hg(-1). LBNP reduced the baroreflex response to 2.7+/-0.4 ms x mm Hg(-1), but G-suit inflation with LBNP restored the baroreflex response to 4.3+/-0.6 ms x mm Hg(-1). CONCLUSIONS: These results suggest that, in addition to increased venous return and elevated peripheral resistance, G-suit inflation may provide protection against the debilitating effects of blood distribution to the lower extremities during orthostatic challenges such as standing or high +Gz acceleration by increasing cardiovascular responsiveness to carotid baroreceptor stimulation.
INTRODUCTION: To test the hypothesis that G-suit inflation could increase cardiac chronotropic responses to baroreceptor stimulation and enhance baroreflex buffering of BP, the carotid-cardiac baroreflex response of 12 subjects was measured across two levels of lower body negative pressure (LBNP = 0 and 50 mm Hg) and two levels of G-suit inflation (0 and 50 mm Hg) in random order. METHODS: Carotid-cardiac baroreflex stimulation was delivered via a silastic neck pressure cuff and responsiveness quantified by determination of the maximum slope of the stimulus-response function between R-R intervals (ms) and their respective carotid distending pressures (mmHg). RESULTS: Mean +/- SE baseline control baroreflex responsiveness was 3.8+/-0.4 ms x mm Hg(-1). LBNP reduced the baroreflex response to 2.7+/-0.4 ms x mm Hg(-1), but G-suit inflation with LBNP restored the baroreflex response to 4.3+/-0.6 ms x mm Hg(-1). CONCLUSIONS: These results suggest that, in addition to increased venous return and elevated peripheral resistance, G-suit inflation may provide protection against the debilitating effects of blood distribution to the lower extremities during orthostatic challenges such as standing or high +Gz acceleration by increasing cardiovascular responsiveness to carotid baroreceptor stimulation.
Authors: Victor A Convertino; Duane A Ratliff; Kathy L Ryan; William H Cooke; Donald F Doerr; David A Ludwig; Gary W Muniz; Deanna L Britton; Savran D Clah; Kathleen B Fernald; Alicia F Ruiz; Ahamed Idris; Keith G Lurie Journal: Clin Auton Res Date: 2004-08 Impact factor: 4.435
Authors: Heberto Suarez-Roca; Rebecca Y Klinger; Mihai V Podgoreanu; Ru-Rong Ji; Martin I Sigurdsson; Nathan Waldron; Joseph P Mathew; William Maixner Journal: Anesthesiology Date: 2019-04 Impact factor: 7.892
Authors: Marta Carrara; Giovanni Babini; Giuseppe Baselli; Giuseppe Ristagno; Roberta Pastorelli; Laura Brunelli; Manuela Ferrario Journal: J Appl Physiol (1985) Date: 2018-07-12