(109) Mesenteric near Infrared Spectroscopy in Patients with Post-operative Congenital Heart Disease

Background: In patients with congenital heart disease (CHD), mesenteric organs are at risk for ischemic injury due to inadequate oxygen delivery. Studies have demonstrated the importance of enteral nutrition in the clinical course of critically ill pediatric patients. However, uncertainty remains regarding the role of enteral nutrition in CHD patients with hemodynamic instability. Additionally, vasoactive agents can further alter mesenteric perfusion. Near infrared spectroscopy (NIRS) provides continuous, non-invasive, monitoring of regional tissue oxygen saturation (rSO2), and is highly determined by regional venous oxygen saturation, an index of the regional oxygen supply/demand relationship.

Objectives: To determine if mesenteric regional saturations in postoperative infants with congenital heart disease are altered by enteral nutrition, with and without the use of vasoactive agents.

Design/Methods: This was a prospective, observational study of infants with CHD who underwent biventricular surgical repair. We obtained demographic, clinical, operative, and enteral nutrition data from the electronic health record. Oximetric data were captured continuously by NIRS in cerebral, renal, and mesenteric beds and by pulse oximetry. Relationships to vasoactive medication, feeding, and postoperative time will be assessed using multilevel regression models. Data are represented as mean +/- SD or count [percent].

Results: The study population included 29 patients, 21/29 [72.4%] male, age 15.5 +/- 13.1 weeks, and weight 5.0 +/- 1.5 kilograms at study initiation. Intraoperatively, 22 [75.9%] patients underwent cardiopulmonary bypass (CPB), for 128.8 +/- 54.3 minutes. Aortic cross-clamp was used on 27 (93.1%) patients for 73.2 +/- 40.1 minutes. Vasoactive medications initiated after CPB included epinephrine (22 [75.9%] patients), milrinone (20 [69.0%] patients), norepinephrine (2 [6.9%] patients), and nicardipine (1 [3.4%] patient). Feeds were initiated at 30.4 +/- 17.7 hours following ICU admission. Mesenteric NIRS monitoring was obtained for 36.6 +/- 23.6 hours.

Conclusions: We anticipate that mesenteric rSO2 will decrease during the post-prandial state compared to the pre-prandial state, suggesting an increased risk of mesenteric ischemia following enteral feeding in these patients with hemodynamic vulnerabilities following surgical repair, thus rejecting the null hypothesis. We will explore relationships to vasoactive medications, although these are typically adjusted based on observable hemodynamic measures.