Cerebral Oximetry after Low Pressure versus Standard Pressure Pneumoperitoneum in Laparoscopic Nephrectomy.

Abstract

To evaluate whether pneumoperitoneum pressure lower than the standard pressure would allow higher cerebral oxygen saturation (rSO2) during laparoscopic nephrectomy (LN). Randomised controlled trial. Ondokuz Mayis University Hospital, Samsun, Turkey, from January to November 2020. Sixty-two patients (aged 18-65 years; ASA I-III) scheduled for LN were equally divided into a low-pressure (LP; 8 mmHg) and standard-pressure (SP; 14 mmHg) group. Mechanical ventilator settings were adjusted to maintain 32-37 mmHg ETCO2 and >96% SpO2 throughout the surgery. The rSO2 was evaluated by near-infrared spectroscopy before and one minute after induction and then every five minutes until patient transfer to the recovery unit. Oxygen and carbon dioxide partial pressures, pH, and haemoglobin, recorded at five minutes after induction, five and 30 minutes after insufflation, and 10 minutes after desufflation, were examined for correlations with rSO2. Both groups had similar rSo2, arterial blood gas, and haemoglobin values at all measurement times. The LP group showed no differences between the preoperative values and the values obtained at the different time points. In contrast, the SP group showed significant differences between the preoperative and the measured values (except at 25, 30, and 35 minutes) (p = 0.001). Four patients (12.9%) in both groups showed cerebral desaturation. The rSO2 values were moderately correlated with the CO2 and haemoglobin values. Low insufflation pressure offered no advantages over standard pressure in terms of haemodynamics, arterial blood gases, cerebral oxygen saturation during LN, and CO2 insufflation did not change rSO2 levels. Key Words: Pneumoperitoneum, Spectroscopy, Oximetry, Nephrectomy, Surgery, Laparoscopic nephrectomy.