Effect of patient positioning on anesthesiologic risk in endourological procedures

The objective is to compare supine and prone positions in terms of arterial blood gas during lithotripsy endourology procedures in different stages.

Cases of during lithotripsy endourology procedures in our department from March to September 2020 were included prospectively. The variables registered were body mass index, age, the American Society of Anesthesiologists (ASA) score, diabetes mellitus, positive end-expiratory pressure (PEEP), FiO₂, stone size, stone location, procedural type, position, procedure duration, PaO₂, SaO₂, PaCO₂, pH, and dynamic compliance. PaO₂, SaO₂, PaCO_2, pH, and dynamic compliance were recorded at the beginning of the procedure, 5 min later, 15 min later, and at the end of the procedure.

Thirty patients in prone position and 30 in lithotomy position were included in this study. Patients in prone position underwent percutaneous nephrolithotomy, and patients in supine/lithotomy underwent retrograde intrarenal surgery or ureteroscopy. Statistically significant differences were found in PEEP, duration, PaO₂ at the beginning, SaO₂ at the beginning and at the end of the procedure, PaCO₂ at the beginning and at minute 5 and pH at the beginning of the surgery. The saturation PaO2 increased significantly on prone position and was statistically significantly better at the end of the surgery.

Both prone and supine positions were safe regarding anesthesiologic risk and had no clinically relevant differences in terms of individual comparisons in arterial blood gas parameters in static moments of the procedure. Prone position was related to an increase in PaO₂ and a drop in PaCO₂ gradually from the beginning to the end of the surgery.