Analgesic and Opioid Sparing Effects of Preoperative Thoracic Paravertebral Block: A Double Blind Evaluation of 0.5% Bupivacaine with Adrenaline in Patients Scheduled for Simple Mastectomy

Abstract

Background: Various regional anaesthetic techniques are used for post-mastectomy pain relief; however, thoracic paravertebral block (TPVB) has shown some advantages over other methods. This study sought to demonstrate the post‑operative benefit of pre‑operative TPVB in patients scheduled for simple mastectomy. Methods: The study was carried out on 60 adult female patients with the American Society of Anesthesiologists physical status Class I to III scheduled for unilateral mastectomy. Pre-operatively, a nerve stimulator was used to locate the paravertebral space thereafter bupivacaine with adrenaline or saline was injected into the space. Post-operatively, intravenous morphine patient controlled analgesia was commenced in the two groups for 24 h after the surgery. In addition, intravenous paracetamol 15 mg/kg was administered 6 hourly for 24 h in both groups. Results: The 24 h morphine consumption was significantly reduced in the bupivacaine group compared to the control group (P = 0.000). The Numerical pain rating score was significantly lower in the bupivacaine group than in the control group in the 1st 6 h; P = 0.001. The time to first request for analgesia was significantly longer in the bupivacaine group than the control group (P = 0.000). Nausea was the major side effect detected and this was significantly higher in the control group (P = 0.024). The morphine sparing effect was 65.7% in the bupivacaine group. Conclusion: The study showed that bupivacaine‑based TPVB provided an effective post‑operative analgesic and opioid‑sparing effect for simple mastectomy when compared with a saline‑based control group that received only intravenous morphine patient controlled analgesia and paracetamol.