The effect of heating insufflation gas on acid-base alterations and core temperature during laparoscopic major abdominal surgery

BACKGROUND: Carbon dioxide (CO(2)) has different biophysical properties under different thermal conditions, which may affect its rate of absorption in the blood and the related adverse events. The present study was aimed to investigate the effects of heating of CO(2) on acid-base balance using Stewart's physiochemical approach, and body temperature during laparoscopy. METHODS: Thirty adult patients undergoing laparoscopic major abdominal surgery were randomized to receive either room temperature CO(2) (control group, n = 15) or heated CO(2) (heated group, n = 15). The acid-base parameters were measured 10 min after the induction of anesthesia (T1), 40 min after pneumoperitoneum (T2), at the end of surgery (T3) and 1 h after surgery (T4). Body temperature was measured at 15-min intervals until the end of the surgery. RESULTS: There were no significant differences in pH, PaCO(2), the apparent strong ion difference, the strong ion gap, bicarbonate ion, or lactate between two groups throughout the whole investigation period. At T2, pH was decreased whereas PaCO(2) was increased in both groups compared with T1 but these changes were not significantly different. Body temperatures in the heated group were significantly higher than those in the control group from 30 to 90 min after pneumoperitoneum. CONCLUSIONS: The heating of insufflating CO(2) did not affect changes in the acid-base status and PaCO(2) in patients undergoing laparoscopic abdominal surgery when the ventilator was set to maintain constant end-tidal CO(2). However, the heated CO(2) reduced the decrease in the core body temperature 30 min after the pneumoperitoneum.