Effect of Boussignac continuous positive airway pressure ventilation on Pao2 and Pao2/Fio2 ratio immediately after extubation in morbidly obese patients undergoing bariatric surgery: a randomized controlled trial

Abstract Study Objective Pathophysiological changes after laparoscopic Roux-en-Y gastric bypass may increase the risk of pulmonary complications in morbidly obese patients. The purpose of the study was to assess the impact of immediate postextubation use of Boussignac continuous positive airway pressure (CPAP) on arterial oxygenation in morbidly obese patients undergoing laparoscopic Roux-en-Y gastric bypass. The hypothesis is that the use of CPAP may improve oxygenation in the postoperative period when compared to Venturi mask. Design Randomized controlled study. Setting A tertiary referral hospital. Patients Recruited morbidly obese adult patients undergoing laparoscopic Roux-en-Y gastric bypass. Interventions Boussignac CPAP or Venturi mask was randomly applied immediately after extubation in the operating room and was maintained during the first 2 hours in the recovery room. Measurements Pao 2 and Pao 2 /fraction of inspired oxygen (Fio 2 ) ratio values were measured preoperatively and at 1 (T1), 2 (T2), and 24 hours (T24) after extubation, through arterial blood samples. Secondary outcomes (spirometric parameters) were measured at the same periods. For comparison between groups, Student t test, Mann-Whitney U nonparametric test, and χ 2 test were used. Statistical significance is at P Main Results Twenty-four patients were included, 12 in each group. There were no differences in preoperative evaluation. There were significant differences between groups in Pao 2 and Pao 2 /Fio 2 mean values at T1, T2, and T24, being superior in the Boussignac group. During the 24 hours postextubation, 9% of patients in the Boussignac group and 50% in the Venturi group had a Pao 2 less than 60 mm Hg in at least 1 of the evaluations. After extubation, a Pao 2 /Fio 2 ratio value less than 300 was observed in all patients in the Venturi group and in 55% in Boussignac group in at least 1 of the evaluations. There were no differences in spirometric parameters between groups at T1, T2, and T24. Conclusions Application of Boussignac CPAP for 2 hours after extubation improved oxygenation but did not improve forced expiratory volume at 1 second and forced vital capacity.