CPAP in Patients With Severe Obesity After Anesthesia

The goal of this study is to compare two continuous positive airway pressure (CPAP) settings on heart and lung function in patients with severe obesity after anesthesia. The main questions it aims to answer are: 1. Does a recruitment maneuver and CPAP set to intrathoracic pressure (ITP) improve cardiopulmonary function compared to standard CPAP settings in patients with severe obesity after anesthesia? 2. Does the location of adipose tissue influence the response to CPAP settings in patients with severe obesity after anesthesia? Participants will undergo monitoring of their intrathoracic pressure using an esophageal catheter. In the recovery area after anesthesia, participants will receive two CPAP settings, each for 20 minutes. * Intervention 1: Recruitment maneuver and CPAP will set to the level of intrathoracic pressure * Intervention 2: CPAP set to home settings (if OSA is present) or between 8-10 cmH20 (if OSA is not present).

The current proposed crossover study is a single center, open-label clinical trial in patients who have severe obesity (defined by body mass index greater than or equal to 40 kg/m2) and are recovering from anesthesia. The primary aim is to describe the difference cardiopulmonary function between two settings for continuous positive airway pressure (CPAP), using electrical impedance tomography (EIT), transthoracic echocardiography, and esophageal pressure monitoring to measure response. The secondary aim is to determine whether the location of adipose tissue modifies responses to CPAP settings. The study protocol consists of placing an esophageal catheter to monitor intrathoracic pressure in the operating room when the participant is under anesthesia. In the post-anesthesia care unit, participants will receive two CPAP settings, in random order, for 20 minutes each. One setting is a recruitment maneuver and CPAP set to the level of end-expiratory pressure (intrathoracic pressure). Another setting is a CPAP set to home levels (if known) or 8-10 cmH20 if not on home CPAP. There will be a 10 minute washout period between interventions. Investigators will monitor airway and esophageal pressure, ventilation with electrical impedance tomography, right heart function with transthoracic echocardiography, and abdominal muscle contraction with ultrasound. Waist and hip circumference will be measured prior to CPAP.