The purpose of this study is to determine whether breathing high levels of oxygen during surgery affects oxygen levels after surgery. The second purpose of this study is to determine whether giving positive end expiratory pressure PEEP and high oxygen together affects patients oxygen levels after surgery.

This is a randomized, controlled, blinded trial in patients undergoing non-abdominal surgery of the effect of intraoperative increased inspired oxygen used (FiO2>0.9 vs. FiO2 = 0.3) on non-invasive oxygen saturation (pulse oximetry, SpO2) and amount of required supplemental oxygen in the post-anesthesia care unit (PACU); arterial oxygen partial pressure (PaO2) after 45 minutes in the PACU; room air SpO2 24 hours after surgery, and amount of supplemental oxygen required 24 hours after surgery. The purpose of the study is to determine whether absorption atelectasis induced by use of inspired oxygen concentrations in excess of 90% leads to a higher risk of hypoxemia, as evidenced by room air oxygen values and the need for supplemental oxygen. The objective of this study is to determine whether high inspired oxygen (>0.8), which has been demonstrated to reduce the risk of surgical site infection in patients undergoing colon surgery and other major surgical procedures has side effects that limit its use to prevent infection in lower risk operations.

There are four groups of intraoperative ventilation management in this study. Fi02 0.3 plus PEEP, Fi02 0.3 without PEEP, Fi02 greater than 0.9 plus PEEP 3 to 5 cm of water, Fi02 greater than 0.9 without PEEP.

Inclusion Criteria:

• Patients aged 18-70 years undergoing surgery under general endotracheal anesthesia at the University of Utah Hospital Operating Room and the Huntsman Cancer Hospital Operating room who will be admitted to the hospital for at least 24 hours after surgery

Exclusion Criteria:

• Major (open) abdominal surgery
• Major spine surgery
• Craniotomy surgery
• Surgeries where electrocautery or laser devices may be used near the airway (eg tracheostomy, oral surgery) because of the risk of fire with high inspired oxygen in these cases
• Procedures planned for monitored anesthesia care (MAC) or regional without general anesthesia
• Planned airway management with a laryngeal mask airway rather than an endotracheal tube
• Procedures planned in the prone position because this increases atelectasis
• Planned postoperative intubation
• Planned postoperative care in the intensive care unit
• Recent (within 3 weeks) chemotherapy because of the increased risk of pulmonary oxygen toxicity
• History of bleomycin administration because of the increased risk of pulmonary oxygen toxicity
• Diagnosed Obstructive Sleep Apnea with home continuous pulmonary airway pressure (CPAP) use
• Home oxygen use
• Preoperative room air (RA) SpO2 <90%
• History of spontaneous pneumothorax
• Emergency surgery
• Pregnancy. Women of child-bearing age are routinely screened for pregnancy urine human chorionic gonadotropin, (HCG) on the morning of surgery. Patients with a positive result will be excluded from the study (and most likely will have their elective surgery cancelled).
• Patient refusal