Ultrasound-guided transmuscular quadratus lumborum catheters for elective caesarean section: A protocol for a single-centre, double-blind randomised trial.

Background: Management of moderate-to-severe post-operative pain after elective caesarean section (ECS) is internationally primarily based on either epidural catheters or opioids. However, both techniques are associated with some undesirable adverse events. Bilateral transmuscular quadratus lumborum (TQL) block has proven to reduce opioid consumption significantly in the first 24 post-operative hours following ECS and prolong time to first opioid (TFO) (Hansen CKD, Steingrimsdottir M, Laier GE, et al. Reg Anesth Pain Med. 2019; 10.1136/rapm-2019-100540). We present a randomised controlled trial aiming to investigate whether continuous analgesia via bilateral TQL catheters can prolong TFO after ECS.

Methods: This study is a double-blind, randomised, placebo-controlled trial. Patients should be 18 years or older and scheduled for ECS under spinal anaesthesia to be included. Main exclusion criteria are inability to cooperate, excessive daily intake of opioids and difficult ultrasound visualisation of muscular and fascial structures. Participants are randomised to receive ultrasound-guided injection of either 30 mL ropivacaine 0.2% bilaterally and an elastomeric pump containing 0.2% ropivacaine, or 30 mL saline bilaterally and an elastomeric pump containing saline, 2 hours after catheter placement. The primary endpoint is TFO. Secondary outcomes include pain intensity on a numeric rating scale (NRS), accumulated morphine consumption during 24 hours, displacement frequency of catheters and morphine-related adverse events.

Recruitment Period: Four patients were included from September 2018 to November 2018. Inclusion was resumed in June 2019 and will continue until 24 patients with useful data have been included in the trial. Expected inclusion period is 10-14 months.

Trial Registration: ClinicalTrials.gov identifier: NCT03663478. EudraCT: 2017-003625-15.