title: Effects of Cardiopulmonary Bypass on Renal Perfusion, Filtration, and Oxygenation in Patients Undergoing Cardiac Surgery.
abstract: Acute kidney injury is a common complication after cardiac surgery with cardiopulmonary bypass. The authors evaluated the effects of normothermic cardiopulmonary bypass on renal blood flow, glomerular filtration rate, renal oxygen consumption, and renal oxygen supply/demand relationship, i.e., renal oxygenation (primary outcome) in patients undergoing cardiac surgery.
  
  
  
  Eighteen patients with a normal preoperative serum creatinine undergoing cardiac surgery procedures with normothermic cardiopulmonary bypass (2.5 l · min · m) were included after informed consent. Systemic and renal hemodynamic variables were measured by pulmonary artery and renal vein catheters before, during, and after cardiopulmonary bypass. Arterial and renal vein blood samples were taken for measurements of renal oxygen delivery and consumption. Renal oxygenation was estimated from the renal oxygen extraction. Urinary N-acetyl-β-D-glucosaminidase was measured before, during, and after cardiopulmonary bypass.
  
  
  
  Cardiopulmonary bypass induced a renal vasoconstriction and redistribution of blood flow away from the kidneys, which in combination with hemodilution decreased renal oxygen delivery by 20%, while glomerular filtration rate and renal oxygen consumption were unchanged. Thus, renal oxygen extraction increased by 39 to 45%, indicating a renal oxygen supply/demand mismatch during cardiopulmonary bypass. After weaning from cardiopulmonary bypass, renal oxygenation was further impaired due to hemodilution and an increase in renal oxygen consumption, accompanied by a seven-fold increase in the urinary N-acetyl-β-D-glucosaminidase/creatinine ratio.
  
  
  
  Cardiopulmonary bypass impairs renal oxygenation due to renal vasoconstriction and hemodilution during and after cardiopulmonary bypass, accompanied by increased release of a tubular injury marker.
authors.affiliation: From the Department of Anesthesiology and Intensive Care Medicine at the Sahlgrenska Academy, University of Gothenburg, Sahlgrenska University Hospital, Gothenburg, Sweden.
authors.forename: Lukas
authors.initials: L
authors.lastname: Lannemyr
authors.forename: Gudrun
authors.initials: G
authors.lastname: Bragadottir
authors.forename: Vitus
authors.initials: V
authors.lastname: Krumbholz
authors.forename: Bengt
authors.initials: B
authors.lastname: Redfors
authors.forename: Johan
authors.initials: J
authors.lastname: Sellgren
authors.forename: Sven-Erik
authors.initials: SE
authors.lastname: Ricksten
mesh_terms: D000368:Aged; D006348:Cardiac Surgical Procedures; D002315:Cardiopulmonary Bypass / Q000009:adverse effects*; D003404:Creatinine / Q000097:blood; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology; D006596:Hexosaminidases / Q000097:blood; D006801:Humans; D007668:Kidney / Q000098:blood supply* / Q000503:physiopathology*; D007677:Kidney Function Tests / Q000706:statistics & numerical data; D008297:Male; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology; D012079:Renal Circulation / Q000502:physiology
chemical_list: D003404:Creatinine; D006596:Hexosaminidases; D010100:Oxygen