Arterial to end-tidal carbon dioxide tension difference during laparoscopy. Magnitude and effect of anaesthetic technique.

The relationship between arterial carbon dioxide tension and end-tidal carbon dioxide tension was studied in 25 patients during laparoscopy. Thirteen patients received general anaesthesia and 12 epidural anaesthesia. The overall mean difference between arterial and end-tidal carbon dioxide tensions was 0.44 kPa (95% confidence intervals 0.28-0.60 kPa) which was significantly less than that reported in studies during other procedures. The reasons for this difference are probably associated with the physiological changes induced by CO2 pneumoperitoneum and steep Trendelenburg positioning. The choice of anaesthetic technique did not affect the arterial to end-tidal carbon dioxide tension difference significantly (p greater than 0.9).