Continuous Erector Spinae Block Versus Continuous Paravertebral Block

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 narcotic administration can have significant derogatory long-term effects.

Regional anesthetics can provide targeted, continuous analgesia to select dermatomes with minimal additional patient risk and have become routine components of opioid-sparing intraoperative and postoperative pain management plans for surgical patients at BCH. 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 ICU, PACU and inpatient admissions, earlier mobilization, fewer gastrointestinal complications, and improved patient satisfaction scores.

Given the rapid evolution of the field of regional anesthesia and the fact that there are often multiple approaches for achieving analgesia in a select set of dermatomes, there are often a variety of regional anesthetic options for any given surgery. Some approaches are longstanding and well-studied, but with increasing frequency since the advent of ultrasound guidance, newer, novel nerve block options exist. As it is often expensive and work-intensive to thoroughly evaluate a given regional technique with a controlled pediatric trial, many of these blocks become standards of practice based on anecdote, retrospective analysis, or simply belief in the putative benefits of regional anesthetics.

The investigators are fortunate at BCH to have one of the largest concentrated pediatric surgical populations in the US. They also have an active, and well organized regional anesthesia service. Because of this, the investigators are in a unique position to more thoroughly evaluate the effectiveness and safety of regional anesthesia in children. Furthermore, the investigators feel it is critical that institutions such as BCH take a leading role in documenting the effects of regional anesthesia on the most important outcome measures when considering perioperative medicine. These include overall pain management, surgical healing, functional recovery, long-term pain symptoms, and emotional/behavioral outcomes after surgery.

Recently the ESB has become popular for providing analgesia after a number of anterior chest and abdominal procedures. This is a simple interfascial plane block that can reliably provide unilateral chest and/or abdominal wall analgesia. It has been described in numerous case reports and one case series as an effective block for management of unilateral thoracotomies, unilateral rib fractures, unilateral abdominal incisions and (when used bilaterally) for management of post-sternotomy pain.

As an interfascial plane block in a compressible anatomical space, the ESB is thought to be safe in anticoagulated (or recently anticoagulated) patients. It is fast becoming a preferred anesthetic option for these patients as opposed to neuraxial (e.g. epidural) and paraneuraxial (i.e. paravertebral) nerve blocks.

Given the ESB's potentially favorable risk profile versus the other blocks (it is technically less challenging, more distant from critical structures, and thought to be safe in anticoagulated patients) it could provide both a safer and easier to perform regional anesthesia option for many patients. It also offers a new option for a subset of anticoagulated patients for whom other regional techniques (epidural, paravertebral) are contraindicated.

Indeed, given the current information available related to the ESB, the regional anesthesia service at BCH has begun employing it when possible in circumstances where a PVB would commonly be used but is relatively or absolutely contraindicated. Patients undergoing thoracotomies while anticoagulated for cardiopulmonary bypass, aortic clamping, etc. have been successfully managed with continuous ESBs. In addition, thoracotomies in patients with acquired (e.g. dilutional) and other pathologic coagulopathies have been managed with ESBs. As such, the ESB has been adopted for routine use in specific patient populations at BCH and has even occasionally been utilized in lieu of the more longstanding routine PVBs or epidural blocks for patients without contraindication for such.

Retrospective review of BCH outcomes data for 47 ESBs done for a variety of surgeries and populations has not revealed any significant differences between PVBs and ESBs in terms of adverse events, postoperative opiate use, median pain scores, or other standard outcomes measures. As this data is observational in nature, it is difficult to draw firm conclusions as to the comparative efficacy of the two blocks. However, since there are differences in technical difficulty, relative contraindications, and there exist populations that might benefit from these blocks, it would be prudent to comparatively evaluate these blocks in a controlled, randomized, trial.

The investigators propose to evaluate the comparative efficacy of ESBs and PVBs for patients undergoing unilateral non-cardiac thoracotomy by means of a randomized, controlled non-inferiority study (based on a threshold of clinical significance being defined as a 15% difference) comparing rescue analgesic requirements, rendered as opiate equivalents, at 24 postoperatively. Rescue opiates will be available as needed by means of standard PCA/NCA demand protocols. Secondary measures will include rescue opiate requirements at 48 and 72 hours, pain scores, adverse events, time to discharge from the ICU, time to extubation, patient disposition after surgery, and time to perform the block in the operating room.