Measures to Lower the Stress Response in Pediatric Cardiac Surgery

Cardiac surgery induces a measurable stress response in patients which leads to increased morbidity and mortality post-operatively. Through clinical observation, anesthesiologists have determined that varying the combinations of anesthesia drugs used during surgery and just after reduces the stress response, and by extension, morbidity and mortality. However, only a few studies have explored this phenomenon scientifically.

In this study, we aim to demonstrate comparatively that use of dexmedetomidine in addition to low dose narcotics reduces the stress response in cardiac surgical patients and results in less morbidity and mortality. Additionally, dexmedetomidine (Dex) should facilitate safe early extubation in pediatric cardiac patients, which results in decreased ventilator associated co-morbidities. Patients will be randomly assigned to three groups; one group will receive low dose fentanyl (LDF), one will receive low dose fentanyl with dexmedetomidine (LDF + Dex), and one will receive high dose fentanyl (HDF). Blood samples will be collected post-induction, post-sternotomy, after going on cardiopulmonary bypass, at the completion of surgery, and post-operatively to determine the patients' stress hormone levels. The patients will receive standard post-operative care, and clinical data collected as part of this care will be used to determine the incidence of morbidity and mortality. The results of the blood tests will be correlated with the incidence of morbidity and mortality to demonstrate the relative effectiveness of the different anesthesia methods.

Blood samples will be analyzed for the presence of the stress hormones cortisol, epinephrine, norepinephrine, adrenocorticotropic hormone (ACTH), Interleukin 8 (IL-8), TNF-alpha (Tumor Necrosis Factor), and nitrated albumin. Arterial blood gas, glucose and lactate levels, heart rate, blood pressure, use of vasoactive support, length of ventilator use, post-operative mortality, post-operative morbidity, length of Intensive Care Unit (ICU) stay, and length of hospital stay will be recorded.

Children previously enrolled in the surgery study will complete assessments of their cognitive ability, developmental status, and emotional and behavioral adjustment. For the neuro-developmental outcome follow up, Children's cognitive ability will be assessed using the Stanford-Binet Intelligence Scales, 5th Edition (SB5). The SB5 is a widely-used measure of intellectual functioning that is normed for ages 2 and up. The test takes 30-50 minutes to administer to young children, and provides an overall Intelligence Quotient (IQ) score, as well as scores for five primary factors of cognitive ability: Fluid Reasoning, Knowledge, Quantitative Reasoning, Visual-Spatial Processing; and Working Memory. The SB5 has demonstrated excellent reliability and validity.

Eligibility Criteria:
Inclusion Criteria:

* Childrens with the diagnosis of tetralogy of fallot, ventricular septal defect and atrioventricular septal defect who are under one year of age.

Exclusion Criteria:

* Patients who are having reoperation.
* Patients with comorbidities, such as heart failure.
* Patients receiving digoxin preoperatively.