Opioid-free anaesthesia reduces post-BMS morphine consumption and improves pain management

The use of opioid-free anaesthesia (OFA) reduces post-bariatric surgical morphine consumption and improves pain management without compromising hemodynamic stability or increasing sedation – compared to traditional opioid-based anaesthesia (OBA) - researchers from the Hôtel-Dieu de France Hospital, Saint-Joseph University, Beirut, Lebanon, have reported. They also found that the incidence of postoperative nausea and vomiting (PONV), was not significantly different and overall patient satisfaction was higher with OFA. They concluded that their findings support the use of OFA in bariatric surgery, despite the need for further studies with larger sample sizes.

OFA is a multimodal anaesthesia technique that combines different medications without the use of morphine agents, regardless of the route of administration (intravenous, intrathecal, etc.). For OFA, opioids are replaced by anaesthetic adjuncts, such as ketamine, lidocaine, dexmedetomidine and magnesium.

The authors noted that this anaesthesia technique is increasingly used, especially in bariatric surgery, to avoid opioids’ side effects: respiratory depression, pharyngeal muscle weakness, negative inotropism, postoperative nausea and vomiting (PONV), pruritus, immunomodulation, potential neurotoxicity, and most importantly, hyperalgesia, which can paradoxically cause acute and chronic pain.

Therefore, they designed a study to compare OFA and traditional OBA to assess the postoperative morphine consumption as well as their effects on haemodynamics, pain score, PONV, sedation and patient satisfaction when using a combination of lidocaine, ketamine, magnesium sulfate, dexmedetomidine and dexamethasone for bariatric surgery.

Outcomes

The study included 58 patients: 32 patients received traditional OBA and 26 patients received OFA. The found that morphine consumption was significantly reduced in the OFA group, with a median dose of 8mg compared to 19mg in the group that received traditional OBA (p= 0.001, Figure 1). Beyond the 24th postoperative hour, patients in the OFA group did not consume any more morphine.

Figure 1: Comparison of postoperative morphine consumption at different times between OBA group and OFA group showing statistically significant reduced consumption in the OFA group over time, p < 0.001 (OBA = Opioid-Based Anesthesia, OFA = Opioid-Free Anesthesia)

Regarding pain score (VAS), the difference at the first postoperative hour for VAS at rest, during movement, and during coughing was not significant between the two groups, with (p= 0.905, p=0.805 and p=0.72, respectively). However, VAS decreased over time in both groups, and overall, the VAS scores at rest, during movement, and during coughing were significantly lower in the OFA group compared to OBA group (p=0.021, p=0.001 and p<0.001).

During the intraoperative period, there was no significant difference between the two groups regarding the number of episodes of hypotension, the occurrence of bradycardia or the need for vasopressors. Furthermore, During the first postoperative period, systolic blood pressure (SBP) was lower in OFA group (p=0.021). However, there was no significant difference in SBP beyond the second hour. The MAP, heart rate and respiratory rate were also comparable between the two groups.

There were no significant difference in the sedation scale of patients between the two groups, whether in immediate postoperative recovery in the recovery room (p=0.592) or even later in the surgical ward.

At the end of their hospital stay or at 48hrs after surgery, patients in OFA group were more satisfied than those in OBA group. Sixty-five per cent of subjects who received OFA reported a global satisfaction score of ≥ 8/10, compared to 28% of patients in OBA group (p=0.003).

“The use of OFA combining five different drugs (lidocaine, ketamine, magnesium sulfate, dexmedetomidine and dexamethasone) appears to be beneficial in reducing postoperative morphine consumption and pain scores when compared to conventional OBA for bariatric surgery.,” they concluded. “It gives a comparable hemodynamic stability, with higher satisfaction scores and patients do not need any morphine after the 24th postoperative hour thus OFA deserves to be performed in the absence of contraindications.”

The findings were featured in the paper, ‘Opioid-free anesthesia in bariatric surgery: a prospective randomized controlled trial’, published in the European Journal of Medical Research. To access this paper, please click here