Effects of pneumoperitoneum and reverse Trendelenburg position on cardiopulmonary function in morbidly obese patients receiving laparoscopic gastric banding

We prospectively evaluated the effects of pneumoperitoneum and reverse Tren delenburg position on cardiopulmonary function in 20 ASA physical status II -III morbidly obese patients (body mass index >35 kg m(-2)) undergoing lapa roscopic gastric banding After general anaesthesia was induced, patients' l ungs were ventilated using intermittent positive pressure ventilation (at m easurement times, the following parameters were used: tidal volume 12 mL kg (-1) ideal body weight, respiratory rate of 12 bpm, an inspiratory to expir atory time ratio of 1:2). Haemodynamic variables, blood gas parameters, and lung/chest compliance were recorded: in the supine position, after inducti on of general anaesthesia (T-0, baseline) and induction of pneumoperitoneum (T-1); after placing the patient in a 25 degrees reverse Trendelenburg pos ition (T-2); during the surgical time (T-3); before deflating the abdomen ( T-4); after pneumoperitoneum resolution (T-5), and before the end of anaest hesia, with the patient supine (T-6). The PaO2, PaO2/FiO2 ratio, and lung/c hest compliance decreased during the study. After the pneumoperitoneum had been resolved, lung/chest compliance but not oxygenation parameters returne d to baseline values. The arterial to end-tidal CO2 tension difference prog ressively increased from 0.38 +/- 0.3 kPa (2.8 +/- 12.25 mmHg) (T-0) to 0.6 3 +/- 0.3 kPa (4.73 +/- 2.25 mmHg) (T-6) In morbidly obese patients, underg oing laparoscopic gastric banding, a CO2 pneumoperitoneum markedly affected gas exchange and lung/chest compliance, while positioning the patient in a 25 degrees reverse Trendelenburg position had no beneficial effects.