Postoperative spontaneous breathing with CPAP to normalize late postoperative oxygenation

After intubation for elective upper abdominal surgery 30 patients were randomized in group A or B. Both groups had the same anaesthetics and were ventilated with a tidal volume of 12 ml/kg the rate keeping PaCO2 near 40 mm Hg. Group A was ventilated with ZEEP and group B with PEEP 10 cm H2O. Group A was extubated when VC reached 15 ml/kg and PaCO2 did not exceed 50 mm Hg breathing spontaneously. Group B was allowed to breathe spontaneously with CPAP and PEEP 5 cm H2O (Basel PEEP-WeanerR) for 3 hours before extubation. Measurements: BP, PAP, RAP, HR, Hb, arterial and mixed-venous blood gases with FIO2=0,21. Both groups were similar in age, sex, cigarette consumption, preoperative pulmonary pathology, surgical procedure pathology, surgical procedure and time of operation.