Efficacy of erector spinae plane block for minimally invasive mitral valve surgery: Results of a double-blind, prospective randomized placebo-controlled trial

Study objective: To investigate if an erector spinae plane (ESP) block decreases postoperative opioid consumption, pain and postoperative nausea and vomiting in patients undergoing minimally invasive mitral valve surgery (MIMVS).

Design: A single-center, double-blind, prospective, randomized, placebo-controlled trial.

Setting: Postoperative period; operating room, post-anesthesia care unit (PACU) and hospital ward in a university hospital.

Patients: Seventy-two patients undergoing video-assisted thoracoscopic MIMVS via right-sided mini-thoracotomy and enrolled in the institutional enhanced recovery after cardiac surgery program.

Interventions: At the end of surgery, all patients received an ESP catheter at vertebra T5 under ultrasound guidance and were randomized to the administration of either ropivacaine 0.5% (loading of dose 30 ml and three additional doses of 20 ml with a 6 h interval) or normal saline 0.9% (with an identical administration scheme). In addition, patients received multimodal postoperative analgesia including dexamethasone, acetaminophen and patient-controlled intravenous analgesia with morphine. Following the final ESP bolus and before catheter removal, the position of the catheter was re-evaluated by ultrasound. Patients, investigators and medical personnel were blinded for the group allocation during the entire trial.

Measurements: Primary outcome was cumulative morphine consumption during the first 24 h after extubation. Secondary outcomes included severity of pain, presence/extent of sensory block, duration of postoperative ventilation and hospital length of stay. Safety outcomes comprised the incidence of adverse events.

Main results: Median (IQR) 24-h morphine consumption was not different between the intervention- and control-group, 41 mg (30-55) versus 37 mg (29-50) (p = 0.70), respectively. Likewise, no differences were detected for secondary and safety endpoints.

Conclusions: Following MIMVS, adding an ESP block to a standard multimodal analgesia regimen did not reduce opioid consumption and pain scores.