Background: In the postoperative period hypoventilation and hypoxia with hypercarbia may occur in morbidly obese patients due to the residual influence of general anesthesia drugs, postoperative atelectasis and postoperative pain. Non-Invasive Ventilation (NIV) is a method of improvement of respiratory efficiency in patients not requiring mechanical ventilation. The aim of the study was to compare NIV (Boussignac) CPAP and traditional oxygen delivery via nasal catheter in the postoperative acute care unit (PACU) in morbidly obese patients after open Roux-en-Y gastric bypass (RYGBP).
Methods: 19 morbidly obese patients scheduled for elective open RYGBP, were randomly divided into 2 groups: CPAP (10 patients) or control (nasal catheter - 9 patients). Patients consisted of: 8 male and 11 female, mean weight 127.76 +/- 18.5 kg, height 173.41 +/- 9.41 cm, BMI 42.43 +/- 3.3 kg/m2, age 35.84 +/- 9.05 years. In the PACU, capillary blood gas measurements were taken at 3 Time Points: T1 - 30 min, T2 - 4 hours and T3 - 8 hours after admission. Sample T0 was taken before surgery. For management of postoperative pain, patients received morphine 2 mg/h intravenously and tramadol 100 mg.
Results: Mean blood gas measurements of all postoperative time points were: pO2 81.0+/-16.0 (range 78.1-85.7) mmHg vs 65.9+/-4.9 (range 63.8-68.1) mmHg (P<0.05); pCO2 40.6+/-2.4 (range 39.4-41.8) mmHg vs 41.5+/-4.0 (range 39.6-43.4) mmHg (P>0.05), in the CPAP and control groups respectively. In every case, pulse-oxymetry oxygenation was >94%.
Conclusion: Boussignac CPAP improved blood oxygenation compared to passive oxygenation with a nasal catheter but had no influence on CO2 elimination in non-CO2 retaining morbidly obese patients.