Effect of opioid-free anaesthesia on postoperative epidural ropivacaine requirement after thoracic surgery: A retrospective unmatched case-control study

Abstract

Introduction

Patients undergoing thoracic surgery are at risk of severe postoperative pain. Post-thoracotomy pain relief is usually provided with thoracic epidural analgesia (TEA). Intraoperative use of opioids may result in hyperalgesia and increase analgesics consumption. We investigated the effect of opioid-free anaesthesia (OFA) on epidural ropivacaine requirement after thoracotomy.

Methods

This retrospective study compared postoperative epidural ropivacaine requirement of patients undergoing open thoracotomy and receiving either opioid-based anaesthesia (OBA group) or a non-opioid regimen including clonidine, ketamine and lidocaine (OFA group). All patients received postoperative multimodal analgesia including both epidural analgesia and intravenous analgesics. The primary outcome was the cumulative first 48 postoperative hours epidural ropivacaine consumption. Secondary outcomes included postoperative pain scores, requirement for postoperative morphine titration, total opioid analgesics consumption within the first 48 postoperative hours, incidence of nausea and vomiting, intraoperative haemodynamic.

Results

From January 2015 to February 2018, 50 patients received an OBA and 25 received an OFA. The cumulative first 48 postoperative hours epidural ropivacaine consumption was significantly higher in the OBA-group (919 ± 311 mg versus 693 ± 270 mg, P = 0.002). Numerical Rating Scale at 6 and 24 h were significantly lower in the OFA-group (1[0–2] versus 3 [1–5], P = 0.0005 and 1[0–2] versus 3.5 [1–5], P = 0.001). In post-anaesthesia care unit, the proportion of patients requiring morphine was significantly higher in the OBA-group (42% versus 4%, P < 0.001). During anaesthesia, the OBA-group required more vasopressor support, while there were more hypertensive events in the OFA-group.

Conclusion

OFA might reduce ropivacaine consumption, early postoperative pain scores and requirement for morphine titration after thoracotomy.

Introduction

Pain following thoracic surgery is often severe and its inadequate management results in increased postoperative morbidity, especially pulmonary complications (atelectasis, pneumonia, respiratory failure). Chronic pain after thoracotomy is also common, especially in patients who experienced severe acute post-thoracotomy pain [1]. Therefore, management of postoperative pain is still a challenge. Thoracic epidural analgesia (TEA) is one of the available analgesic techniques for pain relief following thoracic surgery [2]. It offers the possibility of reducing opioid requirements and their side effects [3]. This is particularly interesting in thoracic surgical patients with frequent respiratory comorbidities in whom opioids could lead to respiratory depression. Moreover, opioid can also cause acute tolerance and hyperalgesia [4]. Besides, malignant lung disease remains the main indication for lobectomy. Recent findings from retrospective clinical trials, as well as experimental studies strongly suggest that opioids may inhibit cellular immunity, stimulate angiogenesis and accentuate cancer cell growth. Hence, perioperative use of opioids might affect long-term oncological outcomes in the cancer surgical patients [5]. This explains the current trend to use non-opioid drugs as an alternative to opioids for pain management during the perioperative period.

Opioid-Free Anaesthesia (OFA) is a procedure that avoids opioid use during anaesthesia. A combination of several drugs including alpha-2-agonist, low-dose of N-Methyl-D-Asparate (NMDA) antagonist and lidocaine are added to usual hypnotic drug. Modulating peripheral afferent noxious stimulation, these agents may potentiate analgesic effects of opioid. Interestingly, additive analgesic effects of dexmedetomodine [6], as well as ketamine [7] to epidural analgesia have been also previously reported. In patients undergoing renal surgery, low-dose of ketamine potentiates the analgesic effect of epidural thoracic analgesia [8].

In the present investigation, the authors tested the hypothesis that OFA based on alpha-2 agonist, NMDA antagonist and lidocaine could enhance pain relief after open thoracotomy. Therefore, we compared postoperative pain relief of thoracic surgical patients receiving either OFA or opioid-based anaesthesia (OBA) in which a TEA was systematically used.