Continuous Serratus Anterior Blockade for Sternotomy Analgesia Following Cardiac Surgery: A Pilot Feasibility Study.

Inadequate pain relief following cardiac surgery increases morbidity, length of stay in the intensive care unit, persistent pain, and costs. Moderate to severe pain is common after cardiac surgery, peaking during the first and second postoperative day, then decreasing after the third day.

Regional anesthesia as part of a multimodal pain management strategy has become a key feature of cardiac surgery enhanced recovery after surgery (ERAS) protocols. A technique consolidating the pectoralis nerve block (PECS) and serratus anterior plane block (SAPB) into a single injection has been described, also called the serratus anterior plane (SAP) block. Given the relative paucity of evidence assessing the utility of continuous serratus anterior plane block (cSAP) in cardiac surgery, we decided to assess the feasibility of a placebo controlled randomized controlled trial (RCT) with a pilot study.

Primary Pilot Study Objective To assess feasibility of a larger intervention study by measuring recruitment rate, adherence rate, retention rates and continuous serratus anterior plane block (cSAP)-related adverse events following cardiac surgery via median sternotomy.

Methods This study will include patients undergoing valvular replacement/repair and/or coronary artery bypass grafting (CABG) at the QEII Health Sciences Center in Halifax, Nova Scotia. The study will include a maximum of 50 participants, randomly assigned to 2 study arms of 25 participants. A computer-generated random number will be assigned by the central pharmacy to randomize patients on a 1:1 basis to the Ropivacaine and placebo groups.

cSAP block procedure - Study Intervention A member of the cardiac anesthesia or regional anesthesia team will place bilateral serratus anterior catheters under ultrasound guidance within 2 hours of arrival to the cardiovascular intensive care unit. A bolus of study drug 20ml (either ropivacaine 0.2% or normal saline) will be delivered at the time of the block. A 18g multiholed catheter will be inserted and secured to the patients' skin. The same procedure will be followed on the contralateral side. The study drug will be administered by programmed intermittent bolus (PIB) 10ml every 2 hours to each side in a staggered, alternating fashion. The PIB study drug will to be continued for 72 hours post-insertion.