A Comparison of Renal vs Limb NIRS for Predicting Cardiac Surgery Associated Acute Kidney Injury

After 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.