Is there "cardiovascular drift" during and after simulated orthostasis in humans?
This study investigates the time course of hemodynamic variables during and after simulated orthostasis (lower body suction at 55mmHg for 30 mins: LBNP-55).  Individual strategies of blood pressure defense could be observed; LBNP-55 increased heart rate and reduced stroke volume, but was non-hypotensive.  During 20 minutes post-LBNP, heart rate was decreased as well as stroke volume index below pre-LBNP values.  The reduced cardiac index together with unchanged mean arterial pressure gave a highly significant increase of peripheral resistance after LBNP.  The validity of stroke volume results under the experimental conditions given needs to be clarified.
Hinghofer-Szalkay
H G
HG
University of Graz, Department of Physiology, Austria.
László
Z
Z
Rössler
A
A
D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008150:Lower Body Negative Pressure / Q000009:adverse effects*; D008297:Male; D013318:Stroke Volume / Q000502:physiology*; D014655:Vascular Resistance / Q000502:physiology