[Specifics of anesthesiology in the operative phase of laparoscopic surgery]

The present investigation was initiated to quantify the effect of a CO2-peritoneum on CO2-absorption (VCO2res) and other respiratory variables during laparoscopic surgical procedures.

Gas exchange and endtidal pCO2 (petCO2) were measured continuously. Ventilation was adjusted to maintain preoperative petCO2 mainly by increasing the tidal volume. Arterial blood gas samples were taken directly before starting and directly before the end of the CO2-peritoneum.

In 49 patients a complete set of data was evaluated for a mean duration (+/- 50) of 99 (43) min CO2-peritoneum. The mean VCO2res was 37 (30)ml/min. The VCO2 showed a steady state of 137 (29)ml/min before the start of the operation. Individual VCO2res maxima of 223 ml/min were detected. Due to a mean rise of arterial pCO2 (paCO2) of 39 (3.6) to 42.6 (4.5) mmHG the VCO2res was underestimated by about 5 ml/min. This CO2 accumulation was mainly the result of an increasing petCO2-paCO2 difference till the end of the CO2-peritoneum. No significant change in VCO2res has been detected with increasing duration of the CO2-peritoneum, though in individual courses a continuously increasing VCO2res was found. Overweight individuals (n = 17) showed a significantly lower VCO2res of 23 (12)ml/min in comparison to normal weight patients (n = 34) with 43 (16)ml/min. The static total compliance was significantly reduced by 30% at the end of the CO2-peritoneum. The ventilatory deadspeace/tidal volume relation did not change. To maintain normocapnia the average alveolar ventilation had to be increased by 38% till the end of the CO2-peritoneum.

This increase in ventilation can easily be established in pulmonary uncompromised patients. Problems in adequately increasing minute volume are expected in chronic obstructive lung disease and with maximal VCO2res. Monitoring of at least petCO2 is strongly recommended since the individual course of VCO2res cannot be predicted.