Effect of Intraoperative Low-Dose Lidocaine on Mivacurium Requirement in Gynecological Laparoscopy [Letter]

Dear editor

Fu et al, 2026,¹ deserve credit for investigating the potential of intraoperative low-dose lidocaine to reduce mivacurium requirements during gynecological laparoscopic surgery. The authors reported significant reductions in onset time and hourly mivacurium consumption, along with shorter extubation time and lower postoperative pain scores. These findings are certainly intriguing. In the spirit of constructive methodological discussion, we would like to offer a few considerations that may help further refine the interpretation of the results.

First, regarding the clinical relevance of the onset-time difference. The sample size calculation was based on a pilot study estimating a 14.5‑second difference in onset time. The observed difference was 25 seconds. While this discrepancy does not indicate a flaw—small pilot samples can yield imprecise estimates—it does raise a question about what constitutes a clinically meaningful reduction in onset time. Importantly, the observed reduction did not lead to better intubation conditions or improved clinical duration.² We would therefore suggest that future studies consider anchoring the primary outcome to a clinically relevant threshold (eg, achieving excellent intubation conditions within a predefined time window), rather than relying solely on a time-based measure of uncertain clinical value.

Second, the relationship between hourly and total mivacurium consumption may benefit from further clarification. The authors found lower hourly consumption in the lidocaine group but no difference in total consumption. As the authors themselves note in Table 2, surgery duration was numerically longer in the lidocaine group (median 78 vs. 66 min, P=0.356). A lower hourly rate combined with a longer operative time could reasonably result in similar total exposure. Thus, the two findings are not necessarily contradictory. We would suggest that a sensitivity analysis adjusting for surgery duration—or simply presenting a scatterplot of total consumption versus operative time stratified by group—could help readers better understand the relationship between the two metrics.³

Third, the baseline imbalance in uterine myoma warrants a brief comment. Table 1 shows that uterine myoma was more frequent in the lidocaine group (21.2% vs. 6.1%, P=0.073).¹ Myoma surgery often involves longer operative times and potentially higher muscle relaxant requirements. If anything, this imbalance would tend to increase mivacurium consumption in the lidocaine group, thereby biasing against finding a beneficial effect. The fact that the lidocaine group still showed reduced hourly consumption is therefore notable. Nonetheless, to further rule out residual confounding, a sensitivity analysis excluding myoma cases or adjusting for surgical diagnosis could be a useful addition, while acknowledging the modest sample size (N=66).⁴

Finally, regarding postoperative pain scores, the original authors reported reductions only at 6 h and 12 h. We agree with their cautious interpretation and would only add that these are secondary endpoints from a small trial, and the findings should be considered exploratory.

In summary, Fu et al have presented preliminary evidence that lidocaine may reduce hourly mivacurium consumption and shorten onset time. We hope the above considerations—regarding clinical relevance of onset time, interpretation of consumption metrics, handling of baseline imbalances, and cautious reading of secondary endpoints—may be useful for readers interpreting the study and for the authors in their future work.