Can pulse oximetry and end-tidal capnography reflect arterial oxygenation and carbon dioxide elimination during laparoscopic cholecystectomy?

An investigation was carried out on 13 ASA class 1 or 2 adult patients undergoing laparoscopic cholecystectomy. Throughout laparoscopy, the end-tidal PCO2 was continuously monitored by capnography and the arterial hemoglobin oxygen saturation by pulse oximetry. Also, repeated measurements of arterial blood gases were done. Ventilation was controlled using an inspired oxygen concentration of 33% and tidal volume of 10 to 15 ml/kg at a rate of 10-14/min. The report showed that both the mean end-tidal PCO2 and arterial PCO2 progressively increased following carbon dioxide insufflation, to reach a maximal value after 30 min, with no significant change in the arterial-alveolar PCO2 gradient. Also, the arterial PO2 significantly decreased, and the hemoglobin oxygen saturation was always above 98% whether monitored by arterial blood gas analysis or by pulse oximetry. The results suggest that end-tidal capnography and pulse oximetry can be used as noninvasive techniques for monitoring arterial oxygenation and carbon dioxide elimination during laparoscopic cholecystectomy.