A Randomized Single-Blinded Study Comparing Preoperative with Post-Mastectomy PECS Block for Post-operative Pain...

Ultrasound-guided pectoralis muscle blocks (PECS I/II) are well established for postoperative pain control after mastectomy with reconstruction. However, optimal timing is unclear. We conducted a randomized controlled single-blinded single-institution trial comparing outcomes of block performed pre-incision versus post-mastectomy.

Patients with breast cancer undergoing bilateral mastectomy with immediate expander/implant reconstruction were randomized to receive ultrasound-guided PECS I/II either pre-incision (PreM, n = 17) or post-mastectomy and before reconstruction (PostM, n = 17). The primary outcome was the average pain score using the Numerical Rating Score during post-anesthesia care unit (PACU) and inpatient stay, with the study powered to detect a difference in mean pain score of 2. Secondary outcomes included mean pain scores on postoperative day (POD) 2, 3, 7, 14, 90, and 180; pain catastrophizing scores; narcotic requirements; PACU/inpatient length of stay; block procedure time; and complications.

No significant differences between the two groups were noted in average pain score during PACU (p = 0.57) and 24-h inpatient stay (p = 0.33), in the 2 weeks after surgery at rest (p = 0.90) or during movement (p = 0.30), or at POD 90 and 180 at rest (p = 0.42) or during movement (p = 0.31). Median duration of block procedure (PreM 7 min versus PostM 6 min, p = 0.21) did not differ. Median PACU and inpatient length of stay were the same in each group. Inpatient narcotic requirements were similar, as were length of stay and post-surgical complication rates.

Intraoperative ultrasound-guided PECS I/II block administered by surgeons following mastectomy had similar outcomes to preoperative blocks.

This trial is registered with Clinical Research Information Service (NCT03653988).