Is Positive End-expiratory Pressure Required Under General Anesthesia for Short Procedures

Background and Aims: General anesthesia results in some amount of atelectasis in most of the patients. Positive end-expiratory pressure (PEEP) increases functional residual capacity and thereby decreases atelectasis. It is not clear if the expected benefits override the risks associated with PEEP. Hence, we compared the effects of no PEEP and 10 cm H2O PEEP on ventilation, hemodynamic, and oxygenation indices in subjects undergoing elective surgeries in the supine position. Methods: The American Society for Anesthesiologists one and two patients with normal lung function were randomly divided into two groups, of which one group received 7 ml/kg tidal volume with no PEEP, and the other group with 10 cm H2O PEEP. EtCO2, peak airway pressure, heart rate, and blood pressure were noted in both groups. ABG was done first in the preoperative period and the second one after 1 h of the start of the procedure to look for changes in the oxygenation indices in either of the groups. Outcome variables were compared using two-sample t -test or Mann–Whitney U test. Results: There was no difference in ABG parameters between the two groups. We found that in one-fifth of the subjects ventilated with a 10 cm H2O PEEP, there was a rise in EtCO2 which required intervention. The peak airway pressures did not increase >35 cmH2O in 96% of the subjects ventilated with 10 cm H2O PEEP. There was no significant difference in heart rate, blood pressure. Conclusion: A PEEP of 10 cm H2O does not necessarily improve oxygenation. There was no hemodynamic compromise seen.