Factors affecting respiratory function tests in morbid obese patients purchasing laparoscopic sleeve gastrectomy

Obesity is a progressive, chronic and life-threatening disease due to its accompanying diseases. In obese patients, low driving pressure values in mechanical ventilator settings have been shown to be associated with good prognosis. In our study, we aimed to show the change in lung functions caused by different driving pressure application with different end-expiratory positive pressure (PEEP) values in morbidly obese patients who underwent laparoscopic sleeve gastrectomy (LSG) surgery with pulmonary function tests (PFT.) In our prospective, randomized controlled clinical study - after the approval of the ethics committee- was completed with a total of 128 patients whose written consents were obtained between 01/01/2022 and 01/08/2022. The patients age, gender, body mass index (BMI), American Society of Anesthesiologists(ASA) score, comorbidities, mechanical ventilator parameters applied to the patients, and the parameters in the pulmonary function tests performed in the preoperative period and on the 3rd day of the postoperative period were recorded. According to the mechanical ventilator strategies applied during the operation, the patients were divided into 2 groups as Group 1 Driving Pressure Value (ΔP) >15, PEEP applied 5 cm H2O and Group 2 Driving Pressure Value (ΔP) <15, applied PEEP 10 cm H2O. Preoperative and postoperative pulmonary function tests were performed on the patients and the effects of mechanical ventilation strategies were evaluated prospectively. It was determined that the FVC, FEV1, FEF 25%, FEF 75%, FEF 25%-75%, FEFmax, FIVC and FIFmax values of the patients in both groups decreased significantly after surgery. It was determined that the PFT values of the patients with a driving pressure value less than 15 cm H2O were affected less than the patients with a driving pressure value greater than 15 cm H2O. Postoperative deterioration in PFT values of patients receiving general anesthesia can be reduced by lung protective mechanical ventilation strategies. In conclusion; Although it is thought that lower driving pressure values obtained with higher PEEP values applied in obese patients who will undergo LSG surgery may provide lung protective ventilation, more extensive research is needed for the optimization of the applied strategies. Key words: Driving Pressure, PEEP, LSG, PFT