A Review of Pain Control in Pediatric Cardiac Bypass Surgery

Background: Children undergoing cardiac surgery with cardiopulmonary bypass receive high dose opioids for analgesia and to reduce the neurohormonal stress response. While opioids have excellent pharmacodynamics profiles adverse effects include: respiratory depression, bradycardia, nausea, vomiting, and tolerance. Additionally, opioids with short half-lives like fentanyl require several boluses to be administered during surgery causing fluctuating levels analgesia. Several strategies to advance pain control incorporate regional and neuraxial anesthetic techniques, however anticoagulation preclude its routine use. Alternatively using opioids with longer half-lives for analgesia may improve pain control and reduce adverse effects. Objective: The objective of this study is to quantify postoperative opioid requirements in pediatric patients following cardiac bypass surgery. Methods: Electronic medical records were retrospectively reviewed for 64 pediatric patients following cardiac bypass surgery at Children’s National Health System from June of 2014 through February of 2016. Intraoperative and postoperative opioid class and dose was recorded for outpatients with designation ASA class 2-4. The data was compiled and analyzed to obtain a mean and standard deviation for future study. Results: 64 cardiac surgery patients (mean age 4.3±1.7, mean weight 17.1±7.5 kg) receiving between 10-30mcg/kg of fentanyl, the mean total dose of morphine in the first 24-hour postoperative period was 0.363mg/kg, with a standard deviation of 0.239. Conclusions: The data from this internal case review of pain control in pediatric cardiac bypass surgery will be used delineate the appropriate sample size for studying postoperative pain control. This is applicable to our study that compares intraoperatively administered fentanyl to methadone on postoperative opioid requirement. This internal case review of 64 cardiac surgery patients (mean age 4.3±1.7, mean weight 17.1±7.5 kg) receiving between 10-30 mcg/kg of fentanyl showed a mean total dose of morphine in the first 24-hour postoperative period was 0.363 mg/kg, with a standard deviation of 0.239. Assuming no difference between the two treatment strategies in the population, a total sample size of 76 in each group will provide 80% power to detect a difference of 0.109 in means, using a two-sample t-test at the 0.05 significance level. The high amount of postoperative morphine required, as determined by this study, reveals the need to find alternative pain control strategies such as opioids with longer half-lives and regional techniques. Exploring the effectiveness of methadone, a long acting opioid, to reduce postoperative adverse effects is an area of future study