Hemodynamic effects of surgical positioning in patients undergoing percutaneous nephrolithotomy: a prospective study

Different surgical positions can cause varying hemodynamic responses due to their distinct effects on cardiovascular physiology. This study aimed to evaluate the hemodynamic changes associated with supine, lithotomy, and prone positions during percutaneous nephrolithotomy (PCNL) using the Pressure Recording Analytical Method (PRAM). Following ethical approval, 40 patients, aged 18–65 years, with BMI < 30 and classified as ASA physical status I–II, were prospectively enrolled. Patients with known cardiac disease, renal failure, preoperative colloid use, or vasoactive/inotropic drug administration were excluded. A radial artery catheter was placed for continuous invasive hemodynamic monitoring. Parameters including heart rate (HR), mean arterial pressure (MAP), cardiac index (CI), stroke volume index (SVI), pulse pressure variation (PPV), stroke volume variation (SVV), dP/dt max, arterial elastance (Ea), cardiac cycle efficiency (CCE), and cardiac power index (CPI) were monitored using PRAM. Hemodynamic measurements were recorded at six predefined time points: three before (supine, lithotomy, prone) and three after anesthesia induction (supine, lithotomy, prone). Under general anesthesia, HR was higher in the supine position compared to lithotomy and prone (p < 0.001). SVI was lower, and Ea was higher in the supine and prone positions than in lithotomy (p < 0.05). No significant differences were found between positions in MAP, CI, CPI, or CCE. PPV and SVV showed some statistically significant differences, but these were not clinically meaningful. Within each position, general anesthesia caused significant decreases in MAP, CI, SVI, dP/dt max, and CPI (p < 0.05). CCE decreased in all positions, but this was only significant in supine and lithotomy. HR increased only in the supine position. Although Ea increased in all positions during anesthesia, this change was not statistically significant. Before anesthesia, the prone position had lower CI, SVI, CCE, and dP/dt max, and higher Ea compared to the other positions (p < 0.05). These findings highlight the importance of position-specific hemodynamic evaluation in perioperative management. Registration at clinical trial gov. (ID: NCT07109232). The date of the first registration submission was 2022-03-31, and the study started on 2022-05-15.