Comparison of automatic versus constant CPAP in elderly patients after major abdominal surgery: a randomized noninferiority trial

Abstract

Background  Geriatric patients undergoing major open abdominal surgery are at high risk for postoperative pulmonary complications and hypoxemia. Continuous Positive Airway Pressure (CPAP) after surgery may improve postoperative lung function. This randomized controlled trial compared two CPAP techniques ‒ automatic via nasal mask and constant via facial mask ‒ regarding pulmonary function and patient tolerance.

Methods  Sixty patients (≥ 60 years) were randomized (1:1) to receive either automatic CPAP (2-10 cm H₂O) via a nasal mask (Group A) or constant CPAP (7.5 cm H₂O) via a facial mask (Group C) upon arrival in the post-anesthesia care unit. Oxygenation (PaO₂, PaO₂/FiO₂, SpO₂) and spirometry (FVC, FEV₁, PEF) were assessed preoperatively, postoperatively, and one hour after treatment. Comfort scores (0-10, with 0 indicating the best comfort) and complications were recorded.

Results  PaO₂/FiO₂ improvement was lower in Group A (32.6 ± 26.3 mmHg) than in Group C (52.9 ± 40.1 mmHg; p = 0.023). FVC improvement was also lower in Group A (3.7% ± 4.0%) than in Group C (6.7% ± 4.9%; p = 0.012). However, Group A had better tolerance, with lower comfort scores (2 [2-3] vs. 3 [2-4], p = 0.002). Pulmonary function benefits were more pronounced in patients over 70 and those undergoing upper abdominal surgery.

Conclusion  Both CPAP techniques prevent pulmonary decline in geriatric patients post-surgery. While automatic CPAP provides better comfort, constant CPAP improves oxygenation. Although our findings are short-term, they suggest that CPAP mode selection should be tailored based on patient-specific needs.

KEYWORDS
Continuous positive airway pressure; Elderly; Laparotomy; Patient comfort; Pulmonary function tests