Background and aims Thoracic paravertebral block (PVB) is an established technique for perioperative pain management for breast surgery. However, since this block is technically challenging, it has not been widely used. Recently introduced erector spinae plane block (ESPB) requires less technical expertise and may be an alternative to PVB. However, the two blocks have not been fully compared. the present study retrospectively analyzed data saved in our registry to compare the two blocks in patients undergoing breast surgery.

Methods After IRB approval, we extracted data for breast surgery patients receiving either PVB or ESPB under ultrasound guidance from June 2018 to March 2019. We compared intra and postoperative data. the primary outcome was visual analogue pain scores (VAS) at rest at 12 h after block. the secondary outcome included scanning and performing time for block, dermatomal sensory blockade, and postoperative fentanyl consumption for 24 h.

Results 26 PVB and 25 ESPB patients were evaluated. Patient demographics were comparable. VAS at rest at 12 h was similar [PVB 13 (0–30) vs ESPB 25 (12–40), P=0.069] [median (IQR)]. However, VAS at rest at 6 h was lower after PVB [10 (0–24)] than after ESPB [25 (18–40)] (P<0.004). Postoperative fentanyl consumption was less after PVB than after ESPB. All the patients with PVB produced sensory block, whereas 23% of patients with ESPB did. the scanning and performing time for block were both shorter with ESPB.

Conclusions The two blocks had different characteristics but were similar in pain scores at 12 h after block.