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 insignif icant changes in HR and MBP values in both groups (p 0.05). 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.