Efficacy of pectoserratus plane block versus erector spinae plane block on acute and chronic pain after mastectomy: randomized clinical trial

To compare Pectoserratus Plane Block (PSPB) and Erector Spinae Plane (ESP) block regarding perioperative opioid consumption and chronic pain risk among women undergoing elective mastectomy. Single-blind (patients), randomized (1:1) trial. The primary outcome was the composite measure defined as the use of fentanyl intraoperatively or tramadol postoperatively. Secondary outcomes encompassed intraoperative hemodynamics, short (24h), medium (3-months) and long-term (6-months) postoperative pain intensity and complications. 99 patients were randomized (50 in the PSPB group and 49 in the ESP block group). Of these, 93 patients had complete data for the primary outcome. Use of either fentanyl or tramadol was required for 20 of 47 patients (43%) in the PSPB group and 28 of 46 patients (61%) in the ESP block group (Relative Risk [RR] 0.70, 95% Confidence interval [95% CI] 0.47‒1.05, p = 0.09). PSPB-treated patients had a lower risk of tramadol (RR = 0.31, 95% CI 0.12-0.77, p = 0.01) and dipyrone (RR = 0.60, 95% CI 0.39‒0.92, p = 0.02) consumption than ESP block-treated patients. PSPB lowered chronic pain risk at 3-months (RR = 0.66, 95% CI 0.47‒0.92, p = 0.02), with lower scores for the Short-Form McGill Pain Questionnaire (Mean Difference [MD] -2.55, 95% CI -4.31 to -0.78, p = 0.005) and the Douleur Neuropathique 4 Questions questionnaire (MD = -1.08, 95% CI -2.05 to -0.11, p = 0.03). By 6-months, pain outcomes were statistically comparable between groups. Hemodynamic variables and complications were comparable between groups. PSPB and ESP block resulted in similar overall opioid consumption among women undergoing mastectomy. However, PSPB was associated with lower postoperative tramadol consumption.