Medizinische Universität Graz Austria/Österreich - Forschungsportal - Medical University of Graz
Gewählte Publikation:
Hinghofer-Szalkay, H; Loder, I; Rossler, A; Jezova, D.
Neutral point titration: Cardiovascular regulation during combined (LBNP/HDT vs. LBPP/HUT) stimulation
ESA SP PUBL. 2002; 501: 199-200.
Web of Science
- Führende Autor*innen der Med Uni Graz
- Hinghofer-Szalkay Helmut
- Co-Autor*innen der Med Uni Graz
- Rössler Andreas
- Altmetrics:
- Abstract:
- This study was undertaken to identify combinations ('neutral points', NP) of orthostatic (tilt: head-down = HDT, head-up = HUT) and pseudo-orthostatic (lower body pressure: positive = LBPP, negative = LBNP) stimuli able to compensate one another in their effect on hemodynamic variables, electrical thoracic impedance (TI), hematocrit and plasma mass density (PD), and blood hormone concentrations. We asked if NP's exist for tested variables (hypothesis 1), if NP's differ with variables (hypothesis 2), and if NP's change as a function of time (hypothesis 3). For the blood volume sensitive variables (PD, plasma total protein concentration, and hematocrit) we found a NP at greater than or equal to30degrees HDT at LBNP-35 and approximate to15degreesHUT with LBPP+35. There was no clear PD / total plasma protein concentration effect with various degrees of LBNP-15 / HDT. NP's could be derived for some hemodynamic variables: With LBNP-35, a NP for heart rate was derived at approximate to25degrees HDT and for MAP at approximate to30degrees HDT. Heart rate intersected at greater than or equal to30degrees HDT with LBNP-15 (extrapolated), stroke volume index (SVI) at approximate to20degrees HDT. With LBPP+35, SVI had its NP at 11 HUT. The hormonal responses displayed a pattern where plasma renin activity (PRA) NP's were logically scattered with LBNP intensity, whereas aldosterone displayed similar NP's with both LBNP intensities.