purpose:The purpose of this double blinded study was Comparison of ondansetron and meperidine for prevention of PAS in patients undergoing GA for lower extremity surgery.MethodsIn this clinical trial,105 patients with the age of 20-60 y/o and ASA class I,II,III were scheduled for elective orthopedic lower extremity surgery divided randomly assigned to one of three groups: intervention:M(meperidine),O(ondansetron),C(saline) After receieved premedication and immediately before the induction of anaesthesia;Sao2 recorded by pulse oxymeter.in first group,25mg Meperidine IV and in second group,4mg Ondansetron IV and in third group(control),2ml saline IV were administered immediately before the induction.GA in all patients induced equivalently with similar drugs and methods.all patients immediatly after emergence of GA and extubation transported to recovery room(PACU).in the times of 5 and 15 minutes after the enterance to recovery room,Sao2(by pulse oxymeter measurement) and shivering were assessed and recorded by nurse who was unaware of research methods.PAS control was graded with Wernch et al. system (0 = no shivering,1= muscle activity in only one muscle group,2= muscle activity in more than muscle group,3= shivering involving the whom body).Primary outcome measure: post operative cheels
Primary outcome time point :twice( between five -fiftheen min)
Primary outcome method of measurement :four point scale Inclusion: Graps Triminol ;20-60years old
Inclusion cetria :Graps Triminol ;Asa class 1,2,3 ;Under going general anesthesia for lower extremity surgery
exclusion cetria:Cardiovascular disease ,psychiatric dis, thyroid dis, drug allergic reaction - body temperature ≥ 38 or ≤ 36.3 ⁰ c – DM – obesity – procedures which require administration of blood and blood products & anticipated duration more than 180 min.