Study Objective: To evaluate and compare changes in pulmonary mechanics and stress hormone responses between abdominal wall lift (gasless) and carbon dioxide (CO2) insufflation laparoscopic surgery during controlled general anesthesia. Design: Prospective randomized clinical study. Setting: Operating roms at a university medical center. Patients: 12 ASA physical status I and II female patients undergoing laparoscopic resection of ovarian tumors. Interventions: Patients were divided into two groups of six each. the abdominal wall lift group and the CO, pneumoperitoneum laparoscopic group. Following induction of anesthesia, patients were paralyzed and the trachea was intubated. Anesthesia was maintained with isoflurane and nitrous oxide (N2O) in oxygen. Throughout the procedure, patients were mechanically ventilated with a tidal volume of 10 ml/kg and a respiratory rate of 10 breaths per minute. Measurements and Main Results: During the laparoscopic procedure, arterial blood gases, acid-base balance, pulmonary mechanics, stress-related hormones, and urine output were measured and recorded. In the CO2 pneumoperitoneum group, arterial CO, tension increased (p <0.01), dynamic pulmonary compliance decreased (p < 0.01), peak inspiratory airway pressure increased (p <0.01), and plasma epinephrine (p < 0.05), norepinephrine (p < 0.05), dopamine (p < 0.01) and antidiuretic hormones (p < 0.05) increased significantly during the laparoscopic procedure as compared to the abdominal lift group. Adrenocorticotropic hormone anti cortisol increased ns compared to baseline value in both groups (p < 0.05). Urine output was significantly less (p < 0.01) in the CO2 pneumoperitoneum group than in the abdominal wall lift group. Conclusions: Abdominal wall lift laparoscopic surgery is physiologically superior to CO2 pneumoperitoneum laparoscopic surgery as seen during the conditions of this study. Abdominal wall lift laparoscopic surgery provides normal acid-base balance and a lesser degree of hormonal stress responses, it maintains urine output, and it avoids derangement of pulmonary mechanics. (C) 1999 by Elsevier Science Inc.