• truncal blocks
• acute pain
• pain outcome measurement

To the Editor

I thank Swisher and colleagues for their valuable contribution to the literature on the erector spinae plane block (ESPB) with their recent study comparing a single-injection ESPB with a dual-injection paravertebral block (PVB) in nonmastectomy surgery.1 The authors conclude that “PVBs are superior to ESPB for both short-term analgesia as well as opioid-sparing following nonmastectomy surgery” (italics are mine).

However, this statement is not strictly true as the intraoperative and postanesthetic care unit (PACU) opioid consumption met the noninferiority criteria defined by the authors (a difference of 2 mg intravenous morphine equivalents). In addition, the opioid consumption between PACU discharge and follow-up on postoperative day 1 was similar—the median oxycodone dose was 5 mg in the ESPB group versus 10 mg in the PVB group. Neither of these points are mentioned in the abstract. Although the authors chose to define overall noninferiority of the two techniques as having to meet noninferiority criteria for both pain scores and opioid consumption, it is nevertheless important to acknowledge the fact that both techniques have similar opioid-sparing effects. It is also worth emphasizing that the superior analgesia attributed to PVBs only applied to pain scores in PACU; there was no difference in any pain scores (highest or lowest or average) reported by patients on postoperative day 1.

The authors rightly point out that while there is no need to abandon an established PVB practice, there is a role for ESPBs for less-experienced practitioners. The ESPB is clearly simpler to perform and master, as evidenced by the significantly shorter needling time required even by the skilled operators in this study,1 and further confirmed by a recent comparative study in trainee anesthesiologists learning to use both techniques.2 In this era of concern over excessive postdischarge opioid prescribing and use, the potential for the ESPB and other fascial plane blocks to benefit a larger number of patients with their greater reach should not be lightly dismissed.