The Effect of Low Dose Ketamine Infusion on Postoperative Acute and chronic Pain after Thoracotomy

Abstract

Objective: The aim of this study was to investigate the effects of a perioperatively administered low dose of ketamine on postoperative acute, chronic pain following thoracotomy. Methods: Forty patients with ASA I–III and aged between 18 and 65 years were included in the study. Patients were randomly divided into two groups. Group I (n=20) was administered a ketamine 0.5 mg.kg-1 bolus followed by a 2 mcg.kg-1.dk-1 infusion for 24 hours before the incision. Group II (n=20) was given normal saline at the same dose and duration. Postoperative analgesia was achieved through patient-controlled morphine administration. Postoperative resting and moving Visual Analogue Scale values, total morphine consumption, preoperative and postoperative values of FVC, FEV1 and FEF25-75 from pulmonary function tests were recorded. Patients were evaluated in terms ofchronicpain in the surgical incision area at 1 and 3 months after the operation. Nausea, vomiting, agitation, delirium, hallucination and sedation scores were recorded. Results: No statistical difference was found between groups in terms of demographic characteristics and operational features. Visual analogue scale values at rest and on movement were significantly lower in Group I. Total morphine consumption was also significantly lower in Group I. There was no difference between the groups in terms of pulmonary function tests. There was no difference between groups in terms of the incidence of chronic pain and development during the first month after the operation, while the incidence of chronic pain in the third month was significantly lower in Group I.No significant difference was observed between groups in terms of sedation scores. The incidence of side effects such as nausea, vomiting, agitation, delirium and hallucinations was similar in both groups. Conclusion: Low-dose ketamine infusion is an efficient method in postoperative acute and chronic pain management after thoracotomy, it reduces analgesic consumption.