PERIOPERATIVE ANALGESIC EFFECT OF SERRATUS ANTERIOR PLANE BLOCK ON BREAST SURGERY. A PROSPECTIVE, RANDOMIZED, CONTROLLED DOUBLE BLIND STUDY CONDUCTED AT THE KORLE BU TEACHING HOSPITAL, ACCRA, GHANA.

Abstract

INTRODUCTION Breast cancer is the most common cancer in women both in the developed and less developed world, according to World Health Organisation. The mainstay of treatment for breast cancer is breast surgery. Pain after breast surgery has been described as moderate to severe. Inadequately treated post-operative pain after breast surgery invariably leads to greater postoperative morbidity, higher hospital cost and persistent post-operative pain. Opioids have been the drugs of choice for management of postoperative pain after breast surgery, however, they are associated with many undesirable side effects. Serratus anterior plane (SAP) block is a new interfascial injection technique for analgesia of the chest wall. There is paucity of data with regards to its use for pain relief and possible opioid-sparing in the West Africa subregion.

AIM The aim of this study was to determine whether serratus anterior plane block administered for breast surgery has analgesic effect during the perioperative period in patients undergoing elective breast surgery at the Korle-Bu Teaching Hospital.

METHODOLOGY This was a prospective, randomized, double-blinded study. Following Ethical Committee approval, patients who fulfilled the inclusion criteria and gave informed consent were consecutively enrolled into the study. A total of fifty-two (52) patients were enrolled into the study and were randomly assigned into one of two groups. The intervention group (n=26) and the placebo group(n=26). Patients demographic characteristics were recorded. Their pre-induction blood pressure, heart rate, respiratory rate and oxygen saturation were also noted. All patients underwent standard general anaesthesia and their airways secured with laryngeal mask airways. After induction of anaesthesia a blinded anaesthetist performed ultrasound guided serratus anterior plane block with 0.25% plain bupivacaine or 0.9% normal saline. Intraoperatively, heart rate and mean arterial blood pressure were maintained within 20% of the preoperative baseline values by giving intravenous bolus doses of morphine. Intraoperatively, patients’ blood pressure, heart rate and respiratory rate were recorded every five minutes. After surgery, a blinded investigator assessed and noted the numerical rating scale (NRS) score of pain at the recovery ward when patients were conscious and alert, at 1, 4, 8 and 24 hours postoperatively. The incidence of PONV was recorded immediate postoperative period and at 1, 4, 8 and 24 hours postoperatively. Patient satisfaction was also assessed using a simple questionnaire.

RESULTS Patients receiving SAP block had lower NRS scores at all measured time points but this was only statistically significant at 4 hours postoperative time(p-value=0.002). The mean intraoperative opioid consumed (morphine equivalent) was slightly higher in the control group (11.9±1.5mg) than it was in the intervention group(11.3±1.5mg), however the difference was not statistically significant (p value = 0.131) There was statistically significant difference in the postoperative opioid consumption in the intervention group and the control group (4.6±5.7mg versus 10.5 ± 6mg) respectively (p value=0.001). Most participants in this study did not experience PONV. Those who had PONV, the highest incidence occurred 4 hours postoperatively but this was not statistically significant between the two groups (p-value = 0.098). No participant experienced severe PONV. No adverse effects were noticed in those who had the SAP block. Generally, patients in both groups were very satisfied with their postoperative pain management.

CONCLUSION Serratus anterior plane block reduces NRS pain scores postoperatively. It also significantly reduces postoperative opioid consumption but does not significantly reduce intraoperative opioid consumption.