unable to retrieve data from EMR.

Lung protective ventilation (LPV) has been proposed to reduce the incidence of postoperative pulmonary complications (PPCs), and protect against ventilator induced lung injury (VILI).

LPV was first introduced in the intensive care units but has been recently adopted in the operating rooms. Obstructive sleep apnea (OSA) is a widely prevalent condition in obese patients and requires special attention in the operating room. Screening for OSA risk in surgical patients is a common practice. The STOP-BANG questionnaire is a common screening tool for OSA (Snoring, Tiredness, Observed apnea, high blood Pressure, BMI, Age, Neck circumference, and male Gender). The American Society of Anesthesiologists practice guidelines for the perioperative management of patients with OSA do not recommend any specific ventilation strategy to prevent PPCs in this population. To the knowledge of the investigators, the association between intraoperative ventilation strategies and PPCs in laparoscopic bariatric surgery patients, who have a high STOP-BANG score, has not been adequately investigated. The investigators propose a retrospective chart review of patients, 18 years of age and older, who underwent laparoscopic bariatric surgery, in reverse Trendelenburg position, using pressure controlled ventilation (PCV/PCV-VG) at the Ohio State University Wexner Medical Center, between January 01, 2012 and November 22, 2016, to determine whether intraoperative driving pressure is a predictor of postoperative pulmonary complications. No procedures will be done for the sake of conducting this study except for a retrospective review of patient charts. Preoperative and intraoperative variables will be collected to determine their predictive value of postoperative complications. No risks to the patients' health or well being are anticipated due to the conduct of the proposed study. No immediate benefits to the patients from whom data was collected is anticipated either. Results obtained from this study may provide valuable information on the preferred ventilation strategies in the operating room for future patients who have a high risk of postoperative lung complications.

Inclusion Criteria:

• Male or Female
• Age ≥ 18 y/o
• Patients who underwent laparoscopic bariatric surgery
• Surgery under general anesthesia with endotracheal intubation and pressure controlled mode of ventilation (PCV or PCV-VG)

Exclusion Criteria:

• Pregnant females, prisoners
• Short procedures: time of mechanical ventilation < 60 minutes
• Patients who received volume controlled ventilation (VCV) mode
• Patients with past medical history of neuromuscular illnesses, pulmonary hypertension or CHF

Study population will include patients 18 years of age and older who underwent laparoscopic bariatric surgery, in reverse Trendelenburg position, using pressure controlled ventilation (PCV/PCV-VG) at the Ohio State University Wexner Medical Center, between January 01, 2014 and December 07, 2016.