Blood Ropivacaine Concentrations Following Unilateral Chest Wall Nerve Block and Continuous Infusion in Infants and Toddlers Undergoing Thoracotomies

Post-surgical pain management is often suboptimal in pediatric patients, especially in those with complex past medical and past surgical histories. Physicians generally, and physicians at Boston Children's Hospital (BCH), in particular, are employing regional anesthetic techniques as either primary or adjunct measures for perioperative pain control. One of the benefits of regional anesthesia is the avoidance, or at least limitation of, opioid and benzodiazepine exposure.

CUCWNB is a regional anesthesia technique that uses an indwelling catheter, placed under ultrasound guidance, which terminates in the paravertebral space for a paravertebral nerve block or at the base of the erector spinae muscle complex immediately lateral to the paravertebral space for an erector spinae nerve block. Introduction of local anesthetic through this catheter produces ipsilateral somatic and sympathetic nerve blockade in multiple contiguous dermatomes. The technique provides effective analgesia for unilateral thoracic and abdominal surgical procedures.

CUCWNB using ropivacaine is used regularly at this institution for patients of all ages as a part of various multimodal intra- and post-operative pain management strategies. The success of CUCWNB implementation for infants and toddlers undergoing thoracotomies has been so marked that this technique has become essentially a de facto standard of care for this population at BCH.

Unfortunately, even as of today, studies demonstrating the pharmacokinetic profile of ropivacaine CUCWNB in infants and toddlers are not available. A few studies have examined plasma levels of ropivacaine after single injection paravertebral nerve blocks in adult patients. For example, a single bolus injection of 2mg/kg was well tolerated, not exceeding peak plasma concentrations of 2.5 µg/ml, well below the concentration considered a threshold for ropivacaine local anesthetic systemic toxicity (LAST). However, it is unclear how applicable this data is to our complex pediatric surgical patients at BCH.

In order to more fully understand plasma ropivacaine concentrations during CUCWNB, and particularly how these concentrations relate to known thresholds for ropivacaine-induced systemic local anesthetic toxicity, the investigators plan to measure plasma concentrations of ropivacaine at various time points following initiation of CUCWNB in infant and toddler patients having just undergone esophageal atresia repair with posterior tracheopexy.