Vascular rings are a group of aortic arch anomalies that can cause tracheo-esophageal compression. They occur when there is abnormal persistence or regression of the various components of the embryonic arch. The presence of vascular rings alone do not warrant operation, and the indication for surgery is symptom-dependent.A thoracotomy is a common approach for division of a vascular ring. The use of regional anesthesia as intercostal and paravertebral peripheral nerve blocks, and thoracic epidurals may be utilized for supplemental post operative pain control. The aim of this pilot study is to determine if there is indeed a difference in the intraoperative and 24 hour opioid use in patients who received a thoracic epidural versus a paravertebral peripheral nerve block for a division of a vascular ring utilizing an open thoracotomy approach.
Methods and Materials
This pilot study was approved by the Institutional Review Board at Baylor College of Medicine with the need for individual consent waved. 30 patients were identified by the electronic medical record data query who underwent the division of a vascular ring at Texas Children’s Hospital between July 2015 and July 2017. Excel for Windows and STATA were used to conduct statistical analysis. A retrospective chart review was performed to obtain simple demographic data, use of regional anesthesia, intraoperative/24 hour opioid use, and pain scores (2, 12, 24 hours post operatively).
Of the 30 patients identified, approximately half received a regional anesthesia technique: 6 thoracic epidurals, 4 paravertebral blocks, 2 intercostal nerve blocks; and 2 surgical field blocks. The 10 patients that received either a thoracic epidural or paravertebral block were included for data analysis. The demographics for the 4 patients in the paravertebral group are: 5.7 [0.2-15] years and 35 [5.5-70] kg. The demographics for the 6 patients in the thoracic epidural groups are: 8.5 [2-10] years and 35.3 [11.8-45.4] kg. There was no statistical difference in the demographic data of the two groups when examining number of patients, age, and weight. Opioid use was analyzed by converting all intraoperative and 24 hour post operative intravenous and oral formulations into morphine equivalents (ME), and dividing by the patient’s weight in kilograms (kg). The average intraoperative opioid use was 22 [4.25-38] (ME/kg) for the paravertebral group and 18.3 [11.25-25] (ME/kg) for the thoracic epidural group; with no statistically significant difference between the two groups. The 24 hour post operative opioid use in the intensive care unit was 22.75 [15.5-78.2] (ME/kg) for the paravertebral group, and 8 [4.8-28.6] for the thoracic epidural group; with no statistical significance.
Thoracic epidural and paravertebral nerve blocks are an established regional anesthesia technique for pediatric thoracic procedures, no studies have considered opioid use and regional anesthetic technique for children undergoing surgery specifically for vascular rings1–3. There was no statistically significant differences between the demographics of the 2 groups suggesting a similar distribution of subjects, as well as opioid use. Intraoperatively, the uniform limited opioid use could reflect the anesthesiologist’s goal to avoid respiratory depression at the end of the case4. The failure to identify a statistically significant difference in postoperative opioid use could suggest: the need for more subjects (under powered), or that both blocks are indeed equally efficacious for this procedure. Pain scores were not included for final analysis due to the inconsistent data recording in the medical record. This pilot study demonstrates the need for further analysis with a larger group of subjects to determine if a difference exists in the intraoperative and 24 hours opioid use in patients who received a thoracic epidural versus paravertebral neve block for division of a vascular ring, and consider the influence of adjunctive medications.