Noninvasive Cardiac Output Monitoring in Morbidly Obese Patients During Laparoscopic Bariatric Surgery: Effect of Positive End-Expiratory Pressure and Alveolar Recruitment Maneuver

Objective: This study was designed to evaluate the effect of positive end-expiratory pressure (PEEP) and Alveolar recruitment maneuver (ARM) used to improve gas exchange during anesthesia in laparoscopic bariatric surgery on cardiac output parameters using non-invasive thoracic electrical bioimpedance. Study Design: A randomized controlled study was conducted on 30 morbidly obese patients (ASA I and II), with BMI >40kg.m2, scheduled for laparoscopic bariatric surgery were included the study. Setting: International Medical Center (IMC) Hospital, OR department, Bariatric surgery unit, Jeddah, K.S.A. Interventions: Patients were classified into two groups after induction of anesthesia (15 in each): Group I: PEEP was maintained at 10cm H20 prior to peritoneum insufflation with CO2 until the end of the surgery. Group II: The first set of Lung recruitment was achieved prior to insufflation of peritoneum with CO2, by sequential increases in PEEP in three steps from 0 to 20 cm H20. The maneuver was repeated ten minutes after insufflation of peritoneum and lastly the maneuver was done after abdominal deflation. Measurement: Stroke volume index (SVI), cardiac index (CI), and ejection fraction (EF), using non-invasive thoracic electrical bioimpedance, together with heart rate (HR) and mean arterial blood pressure (MAP) were measured in both groups, at three points: To: Prior to, applying PEEP in group I and before starting the first set of Lung recruitment in group II. Ti: 10 minutes after applying PEEP in group I and after starting the first set of Lung recruitment in group II. T2: 10 minutes after abdominal deflation in group I and group II. Results: The patients were comparable regarding their age and BMI. HR was significantly increase in group I and group II at Ti when compared toTo (p=0.01). MBP showed significant decrease at T1 inside group I (p=0.04) and group II (p=0.01) when compared to To. At T2 there were insignificant changes in HR and MBP values in both groups (p>0.05). Correspondence to: Dr. Abdelrady S. Ibrahim, The Department of Anesthesia, Faculty of Medicine, Assiut University SVI and CI showed significant decrease in group I, at Ti and T2 when compared to To, (p<0.05). In group II, SVI and CI values were decreased significantly at Ti (p<0.05) and decreased insignificantly at T2 (p>0.05) when compared to To. EF was statistically insignificant when compared Ti and T2 to To inside each group (p>0.05). In comparison between group I and group II the mean values of HR, MBP, SVI, CI and EF showed insignificant differences at To, Ti and T2. Conclusions: The use of PEEP or alveolar recruitment maneuver to improve arterial oxygenation during laparoscopic bariatric surgery in morbidly obese patients was associated with intraoperative negative hemodynamic changes.