effect of using low-dose ketamine after spinal anesthesia on the severity of postoperative pain in patients with orthopedic surgery

Pain relief is one of the most important goals in patients undergoing surgery without using high-dose opioid analgesics due to their complications. the aim of this study was to evaluate the effect of using low-dose ketamine after spinal anesthesia on the severity of postoperative pain in the patients with orthopedic surgery. the present double-blind clinical trial after obtaining approval was performed on 60 patients with lower limb fracture. the patients were selected by convenience sampling method and then divided into two equal (n=30) intervention and control groups using random number table. the patients in the intervention group after spinal anesthesia received 0.2mg/kg intravenous ketamine diluted with 10cc normal saline. the same amount of normal saline was injected intravenously in the control group. then, the intensity of pain using vas and the level of need for analgesics were measured in both groups at different times up to 24 hours after surgery. the intervention group included 21 males and 9 females with a mean age of 30 ± 1.2 years and control group consisted of 19 males and 11 females with a mean age of 29 ± 4 years. there was no significant difference between the age and sex of the patients in the intervention and control groups (p=0.677), (p=0.589). in the intervention group with the vas, the lowest pain score was found at the first turn of the assessment (2.4 ± 0.6), and the highest pain at 24 h (4.3 ± 2.6). the control group had the lowest pain score at the first turn of the assessment (3.6 ± 0.8) and the maximum pain at the first turn of the assessment (5.2 ± 1.7). according to independent t-test, there was a significant difference between the two groups at all times, except for the first turn of the assessment. in the intervention group, 12 (40%) patients did not receive analgesics within 24 hours. in the control group, 2 (6.7%) had no analgesics. chi- square showed a significant difference between the two groups (p=0.002). the present study showed that low-dose intravenous ketamine could relieve pain in patients and reduce postoperative analgesics.