Regional anesthesia and enhanced recovery: we need more data

To the Editor We thank Drs Koning and Teunissen for their interest in our study. 2 They highlight important points for discourse. First, we thank the authors for highlighting potentially unclear descriptions of studies by Koning et al and Wongyingsinn et al, which did indeed compare spinal analgesia with intrathecal opioid versus control. Importantly, we analyzed the studies appropriately, though the description may have been unclear. We also agree that Wongyingsinn et al were included in the analysis and interpretation, and after removing all studies that only include length of stay (LOS) ≤5 days in the manuscript revisions, one of the Wongyingsinn studies was not included in figures 2 and 3. This had no impact on our findings. Second, Drs Koning and Teunissen highlight an important gap in the literature. They state that intrathecal opioid dosing for colorectal surgery should be in the range of 200–300 μg, but the only evidence presented that this is an appropriate dose was published in 1993, long before the introduction of enhanced recovery after surgery (ERAS). The relevance of these data is uncertain. The evidence published to support a lower dose of opioids in lower limb surgery remains applicable in terms of adverse effects, as these are independent of surgery but rather dependent on the intrathecal morphine dose itself. Given that there remains a dearth of evidence to support any dose ranges in colorectal surgery and the sideeffect profile is not procedure specific, we respectfully disagree with the suggestion of high doses until robust safety and efficacy data support it. Third, Drs Koning and Teusnissen argue our conclusion that “the possible prolonged LOS after epidural analgesia in laparoscopic surgery is a bit overstated”. The basis of this argument is ambiguous. First, we clearly state in table 2 that the certainty of evidence is very low and that there was no evidence of improved LOS with epidural analgesia. We further state in the text that the results were not statistically significant. Moreover, we highlight that for reasons of potentially prolonged LOS, along with delayed mobilization and complications, spinal analgesia should be favored. Taken together, this is a tempered interpretation of the data. That said, we do agree that reducing pain and adverse effects of analgesia are important, but the risks of epidural analgesia on these outcomes suggest that an alternative such as spinal analgesia may be more suitable in laparoscopic settings. Notably, Drs Koning and Teusnissen go on to recommend intrathecal morphine as the gold standard, thereby agreeing with our conclusions. Finally, we thank Drs Koning and Teusnissen for agreeing that studies with a LOS>5 days may not be transferable to contemporary practice and also encourage further studies in this setting, particularly looking at the mode and dosing of regional anesthetic techniques. We encourage further dialogue on this subject with the aims of both understanding the true role of regional anesthesia in the setting of ERAS and continuing to improve patient outcomes.