Impact of Early Enteral Feeding on Splanchnic Blood Flow After Surgery for Critical Heart Disease in the Newborn

Impact of Early Enteral Feeding on Splanchnic Blood Flow After Surgery for Critical Heart Disease in the Newborn

Impact of Early Enteral Feeding on Splanchnic Blood Flow After Surgery for Critical Heart Disease in the Newborn

The objective of this study is to determine the impact of early post-operative feeding on splanchnic blood flow, cardiac output and end organ perfusion, and the patients overall clinical outcomes.

Neonates with critical congenital heart disease (CHD) undergoing surgery often have postoperative decreases in cardiac output. These hemodynamic changes can result in varying levels of organ dysfunction, ranging from the subclinical to the more overt. Although this low cardiac output syndrome (LCOS) and accompanying multiorgan dysfunction syndrome (MODS) is in large part transient, the rapidity and completeness of resolution can vary greatly. During postoperative care in the intensive care unit, knowledge of this phenomenon must be balanced against the desire to initiate enteral nutrition. Many studies have demonstrated that timely initiation of enteral feeds in the intensive care can reduce mortality, morbidity and costs. Practically speaking, the decision to initiate feeds is made based on the patient's postoperative hemodynamic status, a normal lactate, absence of vasopressor agents and presence of bowel sounds. Trophic enteral feeding can usually commence 24h postoperatively, even after complicated neonatal heart surgery, The vast majority of postoperative neonates suffer no apparent ill effects from this management strategy. However, recent data have demonstrated an exceedingly high incidence (3.3-6.8%) of necrotizing enterocolitis (NEC) in CHD patients; a disease for which diminution in splanchnic blood flow and disruption of the mucosal barrier are felt to play an important role. These data suggest the combination of diminished cardiovascular reserve, cyanosis and increased myocardial oxygen demands may promote the development of NEC. Preliminary data from Sickkids (Chanthong and Sivarajan, 2008) demonstrates an NEC incidence of 8% in CHD patients. Patients with NEC also accounted for 25% of all cardiac arrests in Cardiac CCU.

The initial observation period of the study begins in the postoperative period (time 0) after the patient arrives in the Cardiac Critical Care Unit and calibration of the monitors with initial clinically indicated baseline bloodwork is completed. Eligible patients will be randomized when the clinical decision to feed is made (by the treating team) to one of the two treatment arms. Patients in arm 1 will receive continuous nasogastric formula feeding at time 1 and NPO at time 2 (12 hours later).

The initial observation period of the study begins in the postoperative period (time 0) after the patient arrives in the Cardiac Critical Care Unit and calibration of the monitors with initial clinically indicated baseline bloodwork is completed. Eligible patients will be randomized when the clinical decision to feed is made (by the treating team) to one of the two treatment arms. Patients in arm 2 will receive NPO at time 1 and crossover to continuous nasogastric formula feeding at time 2.

Continuous nasogastric formula feeding (using Enfalac with iron 2400 kJ/L at a volume of 1ml/kg/h) at time 1 and NPO at time 2 (12 hours later)

NPO at time 1 and continuous nasogastric formula feeding (using Enfalac with iron 2400 kJ/L at a volume of 1ml/kg/h) at time 2 (12 hours later).

Change in ultrasound derived bloodflow in superior mesenteric artery after feeding by 1 SD from prefeeding value.

Impact of Feeding on: Cardiac Output as measured by continuous mass spectometry, Fractional splanchnic output, Renal Perfusion, Tonometric, Assessment of gastric mucosal pH e. Cerebral oxygen delivery using the NIRS probe

Correlation and Agreement between: Echo and continuous cardiac output measures; gastric tonometry, SMA PSV and qualitative Bowel Perfusion Index; renal artery PSV and temporal urine output

Patient Outcomes: Survival, Time to Extubation, Duration of Postop ICU Admission, Duration of Postop hospital Admission, Discharge weight, Number of Nosocomial Infections, Development of NEC

Inclusion Criteria: neonates ≤ 30 days of postnatal age at time of operation birthweight > 2.5 kg gestational age at birth ≥ 35 weeks Patients requiring cardiac surgery who are expected to remain intubated in the CCIU for > 48 hours informed consent by parent or guardian approval by treating critical care staff physician Exclusion Criteria: patients with heterotaxy or pre-existing renal or abdominal pathology (eg. preoperative diagnosis of NEC). need for ECMO after repair within the study period (data up to that point will be recorded and analyzed). Parent refusal of formula for purposes of study Patient on vasopressin or norepinephrine infusion Parent or legal guardian refuse consent