To investigate if an erector spinae plane (ESP) block decreases postoperative opioid consumption, pain and postoperative nausea and vomiting in patients undergoing robotically-assisted minimally invasive direct coronary artery bypass surgery (RAMIDCAB).

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

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

Sixty-four patients undergoing RAMIDCAB surgery via left-sided mini-thoracotomy and enrolled in the institutional enhanced recovery after cardiac surgery program.

At the end of surgery, patients received an ESP catheter at vertebra T5 under ultrasound guidance and were randomized to the administration of either ropivacaine 0.5% (loading dose of 30 ml and three additional doses of 20 ml each, interspersed with a 6 h interval) or normal saline 0.9% (with an identical administration scheme). In addition, patients received multimodal analgesia including acetaminophen, dexamethasone and patient-controlled 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.

Primary outcome was cumulative morphine consumption during the first 24 h after extubation. Secondary outcomes included location and 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.

Median (IQR) 24-h morphine consumption was not different between the intervention- and control-groups, 67 mg (35–84) versus 71 mg (52–90) (p = 0.25), respectively. Likewise, no differences were detected in secondary and safety endpoints.

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