Comparison of opioid-free and opioid-inclusive propofol anaesthesia for thyroid and parathyroid surgery

We read with great interest the article by Wang et al. [1]. They concluded that opioid-free propofol anaesthesia reduced postoperative nausea and vomiting (PONV) in patients undergoing thyroid and parathyroid surgery. However, we have several concerns about this trial.

The primary outcome of this study was the incidence of PONV, defined as a composite outcome that encompasses the rates of nausea, retching and vomiting within the first 48 h postoperatively. However, in the results section, the individual occurrences of nausea, retching and vomiting are not documented separately. This composite outcome may lead to an overestimation of the impact of the intervention on specific outcomes.

The analysis of the severity of PONV as a secondary outcome indicates that significant differences in PONV rates within the first 24 h postoperatively are limited to mild symptoms, with no statistically significant differences observed for moderate or severe PONV after adjustment. The analyses for both the post-anaesthesia care unit and the 24–48 h postoperative PONV show that only mild levels of nausea and vomiting were present, with no statistical significance between the two groups. The classification of the composite outcome into simple categories of mild, moderate and severe does not facilitate precise analyses of the results. Previous studies have developed optimised assessment scales to evaluate patients' subjective experiences of PONV, revealing that only 1 in 5 patients with PONV display significant clinical relevance [2, 3]. In the present study, a total of 57 instances of PONV were recorded in the first 48 h postoperatively, with only 20 patients requiring anti-emetics and just six reporting severe symptoms. The primary differences in PONV between groups were noted in the mild category; however, this cohort likely experienced minimal subjective discomfort and may not be classified as having clinically significant PONV.

The implementation of a completely opioid-free strategy necessitates a significant increase in the doses of alternative intra-operative medications, such as ketamine or dexmedetomidine, potentially leading to more adverse effects. In this study, patients allocated to the opioid-free group experienced an increased incidence of nightmares or hallucinations and extended tracheal extubation times. Completely avoiding opioids does not convey any inherent advantages and may be associated with adverse effects and increased resource utilisation [4]. For instance, the anaesthesia protocol for the opioid-free group appears to have utilised a greater amount of propofol (740 mg vs. 690 mg). Conversely, patients in the opioid-inclusive anaesthesia group received higher than standard doses of sufentanil, placing them at a greater risk for postoperative opioid-related adverse side effects [5].