Patients with renal insufficiency who undergo cardiac surgery with cardiopulmonary bypass (CPB) are at significant risk for exacerbation of renal dysfunction postoperatively. This in turn is associated with an increased risk of prolonged intensive care unit (ICU) length of stay, other comorbidities including surgical complications and 30-day mortality. Renal impairment is generally identified based on an increase in serum creatinine concentration and/or a certain magnitude decrease in estimated glomerular filtration rate (eGFR). The JuxtaFlow® Renal Assist Device (RAD) is designed to sustain or enhance glomerular filtration perioperatively for patients with renal insufficiency by applying a mild controlled negative pressure to the collecting system via the renal pelvis, thereby increasing effective filtration pressure and reducing tubular pressure. This mechanism is designed to support the kidneys' functions during times of renal stress that would be associated with intrarenal edema, volume overload, increased venous pressure, and inflammatory response. By supporting renal function, specifically during the acute stress of CPB, JuxtaFlow holds promise to protect nephron function, decrease renal hypoxia, and provide multifactorial kidney function support to maintain their ability to manage future stress.