Acute kidney injury (AKI) is a complication of cardiac surgery that can affect outcome. Near Infrared Spectroscopy (NIRS) is a technology that uses light to determine how well oxygenated tissues are. This technology is routinely used in cardiac surgery to measure the oxygen level in the brain by placing a sensor sticker on the forehead. The purpose of the study is to determine whether NIRS sensor stickers placed on the skin over the kidney can predict AKI better than when sensors are placed on the skin over the participant's limbs. This study is being conducted by investigators from the department of anesthesiology at the University of Utah.
We will enroll a convenience sample of adult cardiac surgery patients undergoing procedures that require cardiopulmonary bypass (CPB) and who are at risk for AKI.
Exclusion criteria will include less than age 18 years old, preoperative end-stage kidney disease requiring dialysis, emergency surgery, or patient refusal.
Adult cardiac surgery patients undergoing procedures that require cardiopulmonary bypass (CPB) and who are at risk for AKI (determined by the Cleveland Risk Score greater than 6) at the University of Utah medical hospital.
Cohort
Prospective
NIRS sensor placement
DeviceAfter written informed consent, the patient will be brought to the operating room. Skin tone will be assessed using the Monk scale. Prior to induction of general anesthesia, the right kidney will be located by surface ultrasound, the distance between the renal capsule and the skin will be measured, and a NIRS sensor will be placed on the skin overlaying the kidney. If the patient has had a right nephrectomy, the left kidney will be used. Additional NIRS sensors will then be placed over the patient's ipsilateral biceps and vastus lateralis muscles. The distance from the skin to the muscle tissue will be measured and recorded using ultrasound. NIRS sensors will also be placed on the patient's forehead to measure cerebral oximetry as is current practice at our institution for all cardiac surgeries requiring cardiopulmonary bypass.
Development of post-operative acute kidney injury (AKI) in adult cardiac surgery patients
The objective of this study is to compare perioperative renal NIRS and limb NIRS and determine whether these measurements can predict acute kidney injury in adult cardiac surgery patients. The primary outcome will be the as defined by the Kidney Disease: Improving Global Outcomes (KDIGO) guidelines. Measured by an increase in serum creatinine greater than 0.3mg/dl (48 hours) or an increase in serum creatinine greater than 1.5 times baseline (7 days).
The development of severe acute kidney injury (AKI)
Post-operative AKI as defined by the Kidney Disease: Improving Global Outcomes (KDIGO) guidelines. Measured by an increase in serum creatinine greater than 2.0 - 2.9 times baseline (KDIGO stage 2) or an increase in serum creatinine greater than 3.0 times baseline or greater than 4mg/dl or the initiation of renal replacement therapy (KDIGO stage 3)
Ventilator times
Length of time patient is on ventilator
ICU and hospital length of stay
Time patient is in pre-operation (pre-cardiopulmonary bypass(CPB)), operation (CPB), Post-operation (post-CPB), and ICU.
In-hospital mortality
Number of in-hospital, operative and/or post-operative (cardiopulmonary bypass) deaths
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