[Respiratory mechanics and gas exchange in anesthesia for laparoscopic cholecystectomy]

Abstract

Objective: To evaluate the influence of endoabdominal CO2 insufflation during anaesthesia for laparoscopic cholecystectomy on airway pressure, gas exchange and their relationships.

Design: Perspective; clinical investigation.

Setting: Operating room at a central general hospital.

Patients: 14 patients (3 males and 11 females) ASA 1-2, non smokers, without lung disease, scheduled for elective laparoscopic cholecystectomy.

Interventions: During balanced anaesthesia (N2O/O2, Fentanyl, Isoflurane), with fixed minute ventilation, endoperitoneal insufflation of CO2 held at constant pressure (21 cm H2O).

Measurements: Serial measurements of: Airway pressure, near-static compliance, ETCO2, CO2 minute production, blood gas analysis and derived data: P(a-A)O2, P(a-ET)CO2, Vd/Vt.

Main results: During insufflation peak and pause pressures increased by 6 cm H2O and mean pressure; by 3 cm H2O; Compliance was reduced by 48%; PaO2 decreased evenly with time (p > 0.05) irrespective of the airway pressure. PaCO2, PECO2, VCO2 and Vd/Vt after a sharp increase stabilized at 30% (mean value) over the baseline. P(a-ET)CO2 and Vd/Vt fluctuate in the physiological range except for two short but significant changes (p > 0.05) at insufflation and desufflation time.

Conclusions: Laparoscopic technique for cholecystectomy, at least in healthy patients, produces relevant changes in airway pressures but only minor modifications of gas exchange, similar to those seen during general anaesthesia. This technique can be safely used for routine operation with standard monitoring equipment.