Aminophylline on Perioperative Lung Mechanics in COPD Morbidly Obese Patients Undergoing Laparoscopic Bariatric Surgery

Inclusion Criteria: * Age from 20 to 60 years. * Patients scheduled for laparoscopic bariatric surgery not exceeding three hours under general anesthesia. * American Society of Anesthesiologists (ASA) class II to III. * Patients who had no previous abdominal surgery. * Patients with a body mass index (BMI) greater than 40 kg/m2and suffered obstructive lung disease diagnosed by pulmonary function tests (; forced vital capacity (FEV1\\FVC) \< 70%). * Patients who are psychologically normal. Exclusion Criteria: * Patients who refuse to participate. * Those with arrhythmia or receiving anti-arrhythmic medications. * Those with significant coexisting diseases (e.g. kidney, heart, liver). * Those with known allergy to any of allocated drugs. * Those with excessive intraoperative blood loss more than allowable amount to every patient.