Does hypocapnia before and during carbon dioxide insufflation attenuate the hemodynamic changes during laparoscopic cholecystectomy?

Hypocapnia before and during carbon dioxide (CO2) insufflation for laparoscopic cholecystectomy may reduce the adverse hemodynamic responses. After ethical approval, 100 patients scheduled for laparoscopic cholecystectomy were ventilated using a tidal volume of 8 ml/kg, an inspiration:expiration ratio of 1:2.5, and a positive end-expiratory pressure (PEEP) of 5 cm H2O. At 15 min before CO2 insufflation, the patients were randomly allocated into two groups of 50 patients each. For the normocapnia group, the respiratory rate (RR) was adjusted to maintain arterial CO2 tension (PaCO2) at 35 to 45 mmHg. For the hypocapnia group, the RR was adjusted to maintain PaCO2 at 30 to 35 mmHg. Anesthesia was maintained with sevoflurane 2% to 2.5% in 40% air oxygen and rocuronium. Hemodynamic variables, PaCO2, end-tidal CO2 tension (EtCO2), arterial-to-end-tidal CO2 (Pa-ETCO2) gradient, and RR were recorded. Compared with the control group, the use of hypocapnia before and during pneumoperitoneum was associated with significantly lower arterial blood pressures, lower PaCO2 and EtCO2 values, a higher Pa-ETCO2, a higher RR (p < 0.001), and less need for supplemental doses of fentanyl and labetalol. The authors conclude that the use of hypocapnia before and during CO2 insufflation is effective in attenuating increases in blood pressure after CO2 pneumoperitoneum during anesthesia for laparoscopic cholecystectomy.