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Title: Strategies that improve renal medullary oxygenation during experimental cardiopulmonary bypass may mitigate postoperative acute kidney injury.
Austin Authors: Lankadeva, Yugeesh R;Cochrane, Andrew D;Marino, Bruno;Iguchi, Naoya;Hood, Sally G;Bellomo, Rinaldo ;May, Clive N;Evans, Roger G
Affiliation: Cardiovascular Disease Program, Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Victoria, Australia
Cellsaving and Perfusion Resources, Melbourne, Victoria, Australia
Department of Cardiothoracic Surgery, Monash Health and Department of Surgery (School of Clinical Sciences at Monash Health), Monash University, Melbourne, Victoria, Australia
Pre-Clinical Critical Care Unit, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia
Department of Intensive Care, Austin Health, Heidelberg, Victoria, Australia
Issue Date: Jun-2019 2019-03-15
Publication information: Kidney International 2019; 95(6): 1338-1346
Abstract: Renal medullary hypoxia may contribute to cardiac surgery-associated acute kidney injury (AKI). However, the effects of cardiopulmonary bypass (CPB) on medullary oxygenation are poorly understood. Here we tested whether CPB causes medullary hypoxia and whether medullary oxygenation during CPB can be improved by increasing pump flow or mean arterial pressure (MAP). Twelve sheep were instrumented to measure whole kidney, medullary, and cortical blood flow and oxygenation. Five days later, under isoflurane anesthesia, CPB was initiated at a pump flow of 80 mL kg-1min-1 and target MAP of 70 mm Hg. Pump flow was then set at 60 and 100 mL kg-1min-1, while MAP was maintained at approximately 70 mm Hg. MAP was then increased by vasopressor (metaraminol, 0.2-0.6 mg/min) infusion at a pump flow of 80 mL kg-1min-1. CPB at 80 mL kg-1min-1 reduced renal blood flow (RBF), -61% less than the conscious state, perfusion in the cortex (-44%) and medulla (-40%), and medullary Po2 from 43 to 27 mm Hg. Decreasing pump flow from 80 to 60 mL kg-1min-1 further decreased RBF (-16%) and medullary Po2 from 25 to 14 mm Hg. Increasing pump flow from 80 to 100 mL kg-1min-1 increased RBF (17%) and medullary Po2 from 20 to 29 mm Hg. Metaraminol (0.2 mg/min) increased MAP from 63 to 90 mm Hg, RBF (47%), and medullary Po2 from 19 to 39 mm Hg. Thus, the renal medulla is susceptible to hypoxia during CPB, but medullary oxygenation can be improved by increasing pump flow or increasing target MAP by infusion of metaraminol.
DOI: 10.1016/j.kint.2019.01.032
ORCID: 0000-0002-1650-8939
PubMed URL: 31005272
Type: Journal Article
Subjects: acute kidney injury
cardiac surgery
renal circulation
renal medulla
Appears in Collections:Journal articles

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