The effect of adding lidocaine to patient controlled analgesia with morphine on pain intensity after caesarean section with spinal anesthesia: A double-blind, randomized, clinical trial

Abstract

BACKGROUND: Caesarean section is one of the commonest gynaecological surgeries. AIM: Given the importance of pain relief after caesarean section surgery as well as contradictions in the studies conducted on intravenous lidocaine analgesic effects, this study aimed to evaluate the effect of adding lidocaine to patient-controlled analgesia (PCA) with morphine on pain intensity after caesarean section surgery. MATERIAL AND METHODS: In a double-blinded, randomised clinical trial, 80 women who were scheduled for caesarean section surgery with spinal anaesthesia at Sari Imam Khomeini Hospital in 2017 were randomly assigned into two intervention and control groups. After surgery, all patients were connected to a morphine PCA pump. The PCA solution (total volume = 100 ml) in intervention group contained 50 ml of 2% lidocaine and 30 mg (3 ml) of morphine in 47 ml normal saline. In the control group, the PCA pump contained 30 mg (3 ml) of morphine, and the rest (97 cc) was normal saline. Patients' pain intensity was assessed at 2, 4, 6, 12, 18 and 24 hours after surgery using a visual analogue scale (VAS). Additionally, their postoperative nausea and vomiting, duration of hospitalisation, duration of ileus relapse after surgery, and patients' satisfaction after surgery were evaluated. Data were analysed using SPSS version 22 software. RESULTS: The mean and standard deviation of pain intensity in all patients at the intervals of 2, 4, 6, 12, 18 and 24 hours after surgery were 5.91 ± 1.57, 4.97 ± 1.55, 3.84 ± 1.60, 3.54 ± 1.45, 2.56 ± 1.70 and 0.94 ± 1.70, respectively. Data analysis revealed that, regardless of the groups, postoperative pain intensity significantly decreased (P < 0.0001). However, there were no significant differences between the two groups in terms of mean postoperative pain intensity at any time interval (p > 0.05). Also, there was no significant difference between the two groups in terms of frequency of receiving the diclofenac suppositories after the surgery (p > 0.05). Additionally, there was no statistically significant difference between the two groups in terms of postoperative nausea and vomiting, duration of hospitalisation, duration of postoperative ileus relapse and patients' satisfaction (p > 0.05). CONCLUSION: Based on the results of this study, it seems that adding lidocaine to PCA with morphine, compared with morphine PCA alone, do not have a significant effect on reducing the pain intensity after cesarean section using spinal anaesthesia. Although, further studies with larger sample size are warranted.