Variation in arterial to end-tidal CO2 tension differences during anesthesia in the kidney rest lateral decubitus position

The course of arterial to end-tidal carbon dioxide tension difference [P(a-ET)CO 2 ] was evaluated during general anesthesia in 25 patients scheduled for renal surgery performed in the «kidney position. » The difference between arterial PCO 2 (PaCO 2 ) corrected to body temperature, and end-tidal PCO 2 (PETCO 2 ) measured by mass spectrometry was assessed after induction of anesthesia, after placement in the lateral decubitus position with back arched over a kidney bridge («kidney position»), and every 20 min until the patients were replaced in the supine position at the end of the surgical procedure