Bilateral Continuous Erector Spinae Blocks for Post-Sternotomy Pain Management

Regional anesthesia-and pediatric regional anesthesia in particular-is a rapidly evolving subfield of anesthesia practice driven with considerable urgency by the growing recognition that even appropriate perioperative opioid administration can have significant deleterious long-term effects.

Regional anesthetics can provide targeted, continuous analgesia to select dermatomes with minimal additional patient risk and as such, have become routine components of opioid-sparing intraoperative and postoperative pain management plans for non-cardiac surgical patients at a single institution. In addition to the postulated benefit of reducing overall opioid exposure (and potentially reducing the risk for long term physiologic and behavioral dependence upon opioids), regional anesthetics may allow for earlier extubation after selected surgeries, shorter intensive care unit (ICU) stays, shorter inpatient admissions, earlier mobilization, fewer gastrointestinal complications, and improved patient and care team satisfaction scores.

Historically, regional anesthetics have been avoided in cardiac surgery as most patients are pharmacologically anticoagulated during their procedures and are thus at increased risk for bleeding. This is particularly worrisome in the pediatric cardiac surgical population as many of these children remain intubated for an extended period of time postoperatively and therefore may not have reliable neurological exams in the setting of neuraxial regional anesthetics-potentially resulting in unrecognized hemorrhage-related acquired neurological deficits.

Recently, the erector spinae block (ESB) has become popular for providing analgesia after a number of anterior chest and abdominal procedures. This simple interfascial plane block can reliably provide unilateral chest and/or abdominal wall analgesia. It has been described in numerous case reports and case series as an effective block for management of unilateral thoracotomies, unilateral rib fractures, unilateral abdominal incisions and most notably, for management of post-sternotomy pain when applied bilaterally. New case reports and series involving the ESB are being published almost weekly with a growing number of manuscripts specific to cardiac surgical applications. Indeed, numerous randomized controlled trials have investigated the analgesic efficacy of bilateral erector spinae plane blocks (BESB) compared with conventional treatment for pain after cardiac surgery in adult patients and have been published recently (2018-2019) with promising results.

As an interfascial plane block in a compressible anatomical space, the ESB is considered safe in anticoagulated (or recently anticoagulated) patients. It is fast becoming a preferred anesthetic option at BCH for anticoagulated patients - as opposed to neuraxial (e.g. epidural) and paraneuraxial blocks (i.e. paravertebral) nerve blocks, which are largely contraindicated in this setting. Further, given its relative ease of placement, apparent efficacy and safety profile, it is increasingly becoming a standard option for patients undergoing a wide range of thoracic, abdominal and thoraco-abdominal procedures.

The investigators recently investigated the feasibility of performing these blocks bilaterally in a pediatric cardiac surgical population undergoing sternotomy-based procedures (IRB-P00031524). At the conclusion of this 10-patient pilot, the investigators found that performing these blocks was technically feasible, requiring 30 minutes or less of OR time, resulting in no known complications. Furthermore, the data suggested an approximate 25% reduction in rescue opioid requirements in the first 48 hours amongst the erector spinae group (p=0.048).

In order to best evaluate the efficacy of this block in the pediatric cardiac population, a blinded, randomized and controlled trial would be ideal. However, given that randomization could be challenging and the fact that blinding would not be feasible, the investigators believe an observational prospective cohort study is most appropriate at this time.

As such, the investigators propose to evaluate the comparative efficacy of BESB versus matched historical controls who received standard of care pain management (systemic opioid therapy) for patients undergoing cardiac surgery via sternotomy by means of a single arm, open label, interventional study that will compare as the primary outcome rescue analgesic requirements, rendered as opiate equivalents, at 12, 24 and 48 hours, and the 24 hour period preceding both 72 and 96 hours postoperatively. 'Efficacy' will be considered as a threshold of clinical significance being defined as a 15% difference). In addition to the primary endpoint, we plan to evaluate the duration of intubation, length of ICU stay, median pain scores, incidence of PONV (postoperative nausea and vomiting; 0-6h, 6-12h and overall), time to mobilization and adverse events between these groups. Postoperative data collected from standard clinical follow-up tools, such as return to baseline sleep and activity status as well as pain medication requirements at home, will also be compared. In addition, the investigators plan to evaluate the quality of sleep and activity with a smart watch (Fitbit™ ) during the perioperative period in the BESB group only.

Inclusion criteria

• Scheduled as part of the cardiac surgical ERAS program: Patients scheduled for elective surgeries for the following congenital anomalies, or similar: atrial septal defects (all types), partial anomalous pulmonary venous connection (non-obstructed), cor-triatriatum, VSD, partial AV canal, sub-aortic membrane resection, anomalous aortic origin of the coronary arteries, and pulmonary valve/conduit implantation
• Scheduled for a primary sternotomy.
• Ages 2 years through 17 years.

Exclusion criteria

• Single ventricle physiology.
• Significant scoliosis or other anatomic contraindications to ESB.
• Significant intraoperative hemodynamic instability or bleeding, as ascertained by clinicians taking care of the patient.
• Patients with severe neurodevelopmental delays.
• Patients with previous chronic pain syndromes.
• Patients with a history of greater than 24 hours of postoperative or post-procedural opioid treatment at any point in the 2 months prior to surgery.
• Lack of parental consent and/or child assent.