Effect of Postural Challenges on Non-invasive Cardiac Output Measurement with Impedance Cardiography in Young Healthy Adults Using New Horizontal Electrode Placement Method.

Abstract

Background: Cardiac output is an important hemodynamic parameter of cardiovascular system and a significant indicator of autonomic function status of a person. It can be measured invasively as well as non-invasively. Imepdance cardiography (ICG) is a promising, new, noninvasive technique to measure cardiac output. There are no studies noninvasively measuring cardiac output in healthy subject by impedance cardiography using new horizontal method of electrode placement during postural challenges. Objective: We observed effect of postural challenges on noninvasive cardiac output measurement using ICG by new horizontal electrode placement method. Methods: Cardiac output (CO), stroke volume (SV) and cardiac index (CI), were measured noninvasively, before and after postural challenges namely Head Up Tilt (HUT) of 70 0 and Head Down Tilt (HDT) 20 0 , in 38 healthy male subjects (mean age-28 yrs, range 22-34 yrs). Results: After 70 0 HUT the values of CO, SV and CI decreased by 1.5±0.9 l/min (31%), 25.8±11.4 ml (37%), & 0.8±0.4 l/min/m 2 (27 %), respectively. HDT did not cause significant change in theses hemodynamic parameters. Conclusion: ICG successfully detected physiological changes in cardiac output following postural challenges using new horizontal electrode placement method. The study underscores utility of this simple noninvasive tool for hemodynamic assessment after postural challenge using new horizontal electrode placement method.

Compression Garment-induced Leg Changes Increase Hemodynamic Responses in Healthy Individuals

“…In addition, thigh CSA muscle , SupV, DA and DV were larger when upright possibly because of the orthostatic challenge [29], whereas the COMP applied in the current study may not be sufficient to overcome the orthostatic-induced tissue engorgement [15]. In the upright position, CO and SV were lower [31,32], therefore higher HR was observed to compensate for the orthostatic challenge [32,33]. A previous study showed that 60 mmHg would completely occlude vessels in the upright position in leg pain patients [15], however the COMP applied to significantly compress thigh tissues and its effects in healthy populations warrants further investigation.…”

Cerebral blood flow remains reduced after tilt testing in myalgic encephalomyelitis/chronic fatigue syndrome patients

“…Although the mechanism of the abnormal cerebral blood flow reduction in ME/CFS patients is not fully understood, one of the hypothesized mechanisms is that the abnormal cerebral blood flow reduction is related to an abnormal cardiac output reduction due to increased venous pooling and lack of venous return during the tilt test ( Timmers et al, 2002 , van Campen and Visser, 2018a ). It has previously been shown in healthy controls that cardiac output returns to normal pre-tilt test values within 1 min of the supine recovery phase ( Barde and Deepak, 2012 , Miyake et al, 2014 , Toska and Walløe, 2002 ). In ME/CFS patients the cardiac output in the post-test supine recovery phase has not been studied previously.…”