Erector spinae plane block for postoperative analgesia in robotically-assisted coronary artery bypass surgery: Results of a 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 robotically-assisted minimally invasive direct coronary artery bypass surgery (RAMIDCAB).

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

Interventions: 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.

Measurements: 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.

Main results: 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.

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