DETERMINATION OF CARDIORESPIRATORY FUNCTION AND THE OPTIMUM ANESTHETIC REGIMEN DURING LAPAROSCOPIC SURGERY IN THE RAT MODEL

Background: The rat is increasingly being used in laparoscopic researc h yet the hemodynamic and respiratory effects of CO2 pneumoperitoneum have not been studied in this model. Methods: Five Lewis rats were ane sthetized with inhaled isoflurane (1.4-2.0%) and a 50% O-2/50% N2O mix ture by mask (ISO). Another five rats were anesthetized with 1 ml/kg i ntraperitoneal sodium pentobarbital (PB) and given 100% O-2 by mask. C atheters were placed in the femoral artery and the right jugular vein and a thermistor probe was placed in the aortic arch. Heart rate (HR), blood pressure (MAP), cardiac index (CI), arterial pH, and PCO2 were measured at baseline and following 10, 20, and 30 min of 2 mmHg CO2 pn eumoperitoneum. Results: CO2 pneumoperitoneum had no effect on HR, MAP , CI, pH, or PCO2 in either the ISO or PB anesthetic groups. Comparing the two anesthetic groups, PB demonstrated a significantly higher MAP at all time points, a significantly higher PCO2 at baseline, and 10 m in of pneumoperitoneum, a significantly lower pH at baseline, 10, and 30 minutes of pneumoperitoneum, and a significantly longer induction t ime (31 vs. 6 min). There was no difference in HR or CI between the tw o anesthetics. Conclusion: Low-pressure CO2 pneumoperitoneum up to 30 min in the spontaneously breathing rat does not significantly affect H R, MAP, CI, pH, or PCO2. Inhalational isoflurane/N2O anesthesia produc es less hypertension and respiratory acidosis than intraperitoneal pen tobarbital during pneumoperitoneum in the rat.