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Intraoperative renal hypoxia and risk of cardiac surgery‐associated acute kidney injury
Author(s) -
Ngo Jennifer P.,
Noe Khin M.,
Zhu Michael Z. L.,
Martin Andrew,
Ollason Meg,
Cochrane Andrew D.,
Smith Julian A.,
Thrift Amanda G.,
Evans Roger G.
Publication year - 2021
Publication title -
journal of cardiac surgery
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.428
H-Index - 58
eISSN - 1540-8191
pISSN - 0886-0440
DOI - 10.1111/jocs.15859
Subject(s) - medicine , acute kidney injury , euroscore , cardiac surgery , cardiopulmonary bypass , creatinine , hypoxia (environmental) , myocardial infarction , cardiology , intensive care unit , oxygenation , surgery , anesthesia , oxygen , chemistry , organic chemistry
Background Acute kidney injury (AKI) is common after cardiac surgery requiring cardiopulmonary bypass. Renal hypoxia may precede clinically detectable AKI. We compared the efficacy of two indices of renal hypoxia, (i) intraoperative urinary oxygen tension (UPO 2 ) and (ii) the change in plasma erythropoietin (pEPO) during surgery, in predicting AKI. We also investigated whether the performance of these prognostic markers varies with preoperative patient characteristics. Methods In 82 patients undergoing on‐pump cardiac surgery, blood samples were taken upon induction of anesthesia and upon entry into the intensive care unit. UPO 2 was continuously measured throughout surgery. Results Thirty‐two (39%) patients developed postoperative AKI. pEPO increased during surgery, but this increase did not predict AKI, regardless of risk of postoperative mortality assessed by EuroSCORE‐II. For patients categorized at higher risk by EuroSCORE‐II >1.98 (median score for the cohort), UPO 2 ≤10 mmHg at any time during surgery predicted a 4.04‐fold excess risk of AKI ( p = .04). However, UPO 2 did not significantly predict AKI in lower‐risk patients. UPO 2 significantly predicted AKI in patients who were older, had previous myocardial infarction, diabetes, lower preoperative serum creatinine, or shorter bypass times. pEPO and UPO 2 were only weakly correlated. Conclusions Intraoperative change in pEPO does not predict AKI. However, UPO 2 shows promise, particularly in patients with higher risk of operative mortality. The disparity between these two markers of renal hypoxia may indicate that UPO 2 reflects medullary oxygenation whereas pEPO reflects cortical oxygenation.