Comparison and Evaluation of the Effects of Administration of Postoperative Non-Invasive Mechanical Ventilation Methods (CPAP and BIPAP) on Respiratory Mechanics and Gas Exchange in Patients Undergoing Abdominal Surgery.

OBJECTIVE The aim of our study is to investigate the effect of two different methods of continuous positive airway pressure (CPAP) and bilevel positive airway pressure (BIPAP) and oxygen support under spontaneous ventilation on respiration mechanics, gas exchange, dry mouth and face mask lesion during an early postoperative period in patients undergoing upper abdominal surgery. METHODS Eighty patients undergoing elective abdominal surgery with laparotomy, between the age of 25 and 75 years and American Society of Anesthesiologists Physical Status score (ASA) II-III with chronic obstructive pulmonary disease (COPD) diagnosis were included to the study. Subjects were randomly allocated in to four groups. During the first postoperative hour, the first group received BIPAP, second group received high-flow CPAP, third group received low-flow CPAP and fourth group received deep breathing exercises, respiratory physiotherapy and O2 therapy. Preoperative, postoperative before and after treatment PaO2, PaCO2, SpO2, tidal volume (TV), respiratory rate (RR) levels were recorded. Subjects with dry mouth or face mask lesion were recorded. RESULTS In all groups, PaO2 and TV measurements were higher at the postoperative first hour than the postoperative zero hour. We found that low-flow CPAP increased PaO2 and SpO2 values more, and TV levels were higher in the postoperative period than the preoperative period. PaCO2 levels were elevated at the zero hour postoperatively and at the end of the first hour; they decreased approximately to preoperative values, except in the fourth group. CONCLUSION Administration of prophylactic respiratory support can prevent the deterioration of pulmonary functions and hypoxia in patients with COPD undergoing upper abdominal surgery. In addition, we found that low-flow CPAP had better effects on PaO2, SpO2, TV compared to other techniques.