Near Infrared Spectroscopy for the Detection of Acute Kidney Injury in Children Following Cardiac Surgery

Near infrared spectroscopy (NIRS) is a noninvasive tool used for continuous monitoring of
regional tissue oxyhemoglobin saturation. Sensors are placed on the head and abdomen or
flank and use light to measure the percent oxygen levels in tissues. Head NIRS has been
correlated with oxygen levels of the blood returning from the brain, and an abrupt decline
in post-operative cardiac patients has been shown in retrospective studies to predict an
impending event such as cardiac arrest. Animal studies have demonstrated that somatic NIRS
monitoring is able to detect flow-induced changes in regional oxygen levels of the kidney
and gut directly under the sensor. Unlike cerebral NIRS monitoring, there is no data
regarding the clinical utility of NIRS over the abdomen and flank in predicting outcomes.
Children are at risk of decreased organ perfusion following cardiac surgery, and is a
phenomenon termed low cardiac output syndrome (LCOS). It occurs in approximately 25% of
neonates and young children following cardiac surgery. The effects of LCOS on end organ
function, specifically the kidney may result in acute kidney injury, thereby increasing
morbidity and mortality. The incidence of acute kidney injury (AKI) following cardiac
surgery is reported as high as 40%. The use of NIRS in the operating room to detect AKI in
pediatric patients undergoing cardiac surgery is the focus of this proposal Specific Aim 1:
Determine if a reduction in renal NIRS intra-operatively identifies patients with AKI
Hypothesis: Reduced intra-operative renal NIRS will precede the diagnosis of acute kidney
injury by an increase in serum creatinine within 1 to 3 days post-cardiopulmonary bypass
Specific Aim 2: Determine if a reduction in renal NIRS intra-operatively correlates with
increases in emerging biomarkers of AKI.

Hypothesis: Reduced intra-operative renal NIRS will precede the development if AKI as
detected by neutrophil gelatinase-associated lipocalin, IL-6 and IL-18 by at least 2 hours.

Inclusion Criteria:

- All children less than or equal to age 4 undergoing cardiac surgery with the use of
cardiopulmonary bypass at Colorado Children's Hospital

Exclusion Criteria:

- Prior enrollment in the study

- Agre greater than 4 years

- Use of nephrotoxic drugs within 48 hours of surgery

- Underlying renal dysfunction (preoperative estimated Schwartz clearance less than
80ml/min/1.73m2)

- Gestational age less than 34 weeks at the time of surgery

- Withdrawal of care planned