Hemodynamic Changes In Prone Position - A Non-Invasive Physiological Study

Background and Goal of the study: The aim of this physiological study was to observe changes in cardiac output and other hemodynamic parameters after proning and to compare hemodynamic profile of prone position with and without chest and pelvic support.Type of study: Prospective, observational study.Setting: Clinical laboratory of a university hospital.Material and Methods: Twelve healthy volunteers older than 18 years were included in the study. Non-invasive hemody namic measurement was initiated using ClearSight/EV 1000 system in supine position (S position). Cardiac index (CI), stroke volume index (SVI), stroke volume variation (SVV), systemic vascular resistance index (SVRI) and mean arterial pressure (MAP) were recorded. Following parameters were measured using ultrasound at predefined sites: expiratory area of v. cephalica (sVCe), v. saphena (sVSe), v. jugularis interna (sVJe), expiratory and inspiratory area (sVCIe a sVCIi), and maximum and minimum diameter (dVCImax a dVCImin) of v. cava inferior and index of colapsibility (VCI CI) were calculated. Corrected carotid flow time (ccFT) was measured using a Doppler ultrasound. All measurements were repeated in unsupported (P1 position) and supported (P2 position) prone positions with supported chest and pelvic regions.Results and Discussion: There were no differences in CI, SVI, SVV and ccFT values between positions. Significantly different values of MAP and VCI CI were observed between positions. Higher SVRI in P1 position in comparison with S position, higher sVJe in prone positions and lower dVCImin in P2 position in comparison with P1 position were recorded.Conclusion: No differences in cardiac output and preload were detected after proning in unsedated healthy volunteers. Prone position was associated with changes of systemic vascular resistance, blood stagnation in jugular catchment area and, in unsupported prone position, increased collapsibility of inferior vena cava.