IAP Measurements
IAP was estimated from the bladder pressure by injecting 25 ml of saline in the bladder after clamping the urinary drainage bag (AA6118 Folysil; Coloplast, Humlebaek, Denmark) (20). The abdominal pressure transducer was fixed to the patient on the lateral side of the pelvis, 2 cm below the anterior superior iliac spine. Hemodynamic, respiratory, and the IAP signals were continuously computerized(HEM4.2; Notocord Systems, Croissy-sur-Seine, France). All measurements were performed at end-expiration.