Comparison of acetaminophen (with or without tourniquet) and lidocaine in propofol injection pain

Abstract

Background: We aimed to evaluate the effectiveness of i.v. acetaminophen (with or without tourniquet application) in comparison with that of lidocaine for the prevention of propofol-induced pain during induction of anaesthesia. Methods: The patients' arms were elevated for 20 s and a tourniquet was placed. In group 1, 10 ml saline; in group 2, 40 mg lidocaine in 10 ml saline; in group 3, 10 ml (100 mg) acetaminophen were administered; in group 4, the tourniquet was inflated to 100 mmHg, then 10 ml (100 mg) acetaminophen was given and after 2 min, the tourniquet was deflated. In all groups the duration of administration of the solutions were kept constant (10 s). Standard propofol solution (10 mg ml-1) was prepared at room temperature and propofol was given using an infusion pump by a person blinded to the study groups. All treatments were designed to deliver a 2mg/kg dose of propofol in a duration of 3 min. Pain during induction with propofol was scored using a 4-point verbal rating scale (none; 0, mild; 1, moderate; 2, and severe; 3) (VRS). Patients were asked to rate their pain at the injection site after infusion of 1/4 of the solution, after 1/2 of the solution and, if hypnosis has not ensued, after 3/4 of the solution. Results: The groups were found to be different with regard to VRS scores (p<0.001). When the groups were compared in pairs; groups 2,3,4 had better analgesia than group 1 for all VRS values (all p values <0.001); groups 2 and 4 were similar (all p values >0.05) and both had better analgesia than group 3 for all VRS values (all p values <0.001). Conclusion: We concluded that i.v. acetaminophen when given using a tourniquet is as effective as lidocaine on propofol associated pain. Further, acetaminophen administration with tourniquet seems to be superior to acetaminophen without use of a tourniquet.