A Randomized Controlled Trial on Assessment of Analgesia on Using Magnesium Sulphate by Different Routes in Patients Undergoing Arthroscopy of Knee under Spinal Anaesthesia

Abstract

BACKGROUND Adequate pain management has a great importance for smooth postoperative recovery, early hospital discharge and early rehabilitation. In this study, we compare the analgesic effect and possible side effects of different routes of magnesium sulphate administration in cases of spinal anaesthesia for knee arthroscopy. METHODS This is an experimental prospective randomized control study. 196 patients undergoing knee arthroscopy were divided into 4 groups (49 each): Group A: Given bupivacaine intrathecally during spinal anaesthesia. Group B: Given magnesium sulphate 50 mg with bupivacaine intrathecally. Group C: Given magnesium sulphate IV 10 min after intrathecal injection (30 mg/kg MgSo4). Group D: Given magnesium sulphate intra-articular route, 10 min before the end of surgery (800 mgSo4 diluted in 12 ml normal saline (0.9 % NaCl). Operative time in minutes, VAS at rest and after procedure, time lapse before first analgesic dose after surgery, total dose of rescue analgesics used, pulse rate, mean arterial pressure and side effects were observed and analysed. RESULTS In regards to the lapse of time between end of surgery and first rescue analgesic given, total doses of tramadol used during the 24 hours after the procedure were significantly better in patients given intra-articular magnesium sulphate than other groups (P = 0.001). Patients of Group C who received IV magnesium sulphate were significantly better than patients who were given intrathecal magnesium sulphate in relation to time taken from end of surgery until first analgesic dose. VAS at rest and during the period of first 24 hours followed by surgery was statistically significant in patients who received intra-articular magnesium sulphate (p- 0.001). CONCLUSIONS Intra-articular administration of magnesium sulphate was observed to be superior to other routes of administration or not using at all. Next to intra-articular route, intravenous magnesium sulphate was found to be superior to intrathecal route in providing post operative analgesia in arthroscopy patients. KEY WORDS Analgesia, Knee Arthroscopy, Pain, Magnesium Sulphate, Intrathecal, Intra-articular