Short-term hemodynamic variability in supine and tilted position in young men

Abstract

The aim of the study was to evaluate short-term changes in hemodynamic parameters observed in supine and tilted positions in six young men (age: 21–25). The cardiac inter-beat interval (RR), stroke volume (SV), ejection time (ET) and pre-ejection period (PEP) parameters were followed over two six-minute periods, in supine position and 10 min after a 60-degree head-up tilting maneuver, using continuously recorded impedance cardiography (ICG) and electrocardiography (ECG) signals. Hemodynamic variability was evaluated using coefficient of variation (CV), standard deviation (SD), and quartile deviation (QD). For the supine position, the mean (M), SD, CV and QD of the observed parameters were as follows. SV: 79 ml, 16 ml, 20%, 15 ml. RR: 905 ms, 106 ms, 12%, 163 ms. ET: 308 ms, 29 ms, 10%, 33 ms. PEP: 105 ms, 19 ms, 18%, 28 ms. In the tilted position, the following were observed. SV: 54 ml, 12 ml, 21%, 15 ml. RR: 706 ms, 68 ms, 10%, 68 ms. ET: 259 ms, 38 ms, 14%, 28 ms. PEP: 123 ms, 13 ms, 12%, 15 ms. The changes in hemodynamic variability caused by tilting were not unidirectional.