Comparative Study of Effects of Intraoperative Use of Positive End-Expiratory Pressure, Intermittent Recruitment Maneuver, and Conventional Ventilation on Pulmonary Functions during long-Duration Laparotomy.

Abstract

Background:With an increase in the duration of general anesthesia, there is a gradual deterioration in pulmonary functions. Intraoperative atelectasis is the major cause of deterioration in pulmonary functions. This study was performed to compare and determine the best ventilatory strategy among conventional ventilation, application of positive end-expiratory pressure (PEEP), and intermittent recruitment maneuver.Materials and Methods:Seventy-five patients were divided into three groups each of 25 patients. In the first group (zero positive end-expiratory pressure [ZEEP]), we have applied zero PEEP intraoperatively. In the second group (PEEP), we have applied PEEP of 6 cm of H2O. In the third group (intermittent lung recruitment maneuver [IRM]), we have done intermittent recruitment maneuver intraoperatively. Pulmonary functions were analyzed by partial pressure of oxygen (PaO2)/fraction of inspired oxygen (FiO2) ratio (P/F) and static lung compliance (Cstat).Results:While comparing the mean P/F ratio between the groups, a significant decrease in P/F ratio of the ZEEP group was found from 90 min after induction up till the end (i. e. 24 h after extubation) of our observations as compared to both the PEEP and IRM groups. However, it did not differ (P > 0.05) between the PEEP and IRM groups at all time points on statistical analysis. On comparing the mean of Cstat between the groups, there was a significant decrease in lung compliance of the ZEEP group as compared to both the PEEP and IRM groups at all time points. However, like P/F ratio, compliance was also found to be statistically insignificant between the PEEP and IRM groups.Conclusions:Pulmonary functions are relatively preserved with application of either PEEP or doing intermittent recruitment maneuver.