Abstract | INTRODUCTION: METHODS: We continuously measured renal medullary oxygen tension (MPO2) in 24 sheep, and urinary PO2 (UPO2) as an index of MPO2 in 92 patients, before and after induction of CPB. RESULTS: In laterally recumbent sheep with a right thoracotomy (n = 20), even before CPB commenced MPO2 fell from (mean ± SEM) 52 ± 4 to 41 ±5 mmHg simultaneously with reduced arterial pressure (from 108 ± 5 to 88 ± 5 mmHg). In dorsally recumbent sheep with a medial sternotomy (n = 4), MPO2 was even more severely reduced (to 12 ± 12 mmHg) before CPB. In laterally recumbent sheep in which a crystalloid prime was used (n = 7), after commencing CPB, MPO2 fell abruptly to 24 ±6 mmHg within 20-30 minutes. MPO2 during CPB was not improved by adding donor blood to the prime (n = 13). In patients undergoing cardiac surgery, UPO2 fell by 4 ± 1 mmHg and mean arterial pressure fell by 7 ± 1 mmHg during the 30 minutes before CPB. UPO2 then fell by a further 12 ± 2 mmHg during the first 30 minutes of CPB but remained relatively stable for the remaining 24 minutes of observation. CONCLUSIONS: Renal medullary hypoxia is an early event during CPB. It starts to develop even before CPB, presumably due to a pressure-dependent decrease in renal blood flow. Medullary hypoxia during CPB appears to be promoted by hypotension and is not ameliorated by increasing blood hemoglobin concentration.
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Authors | Roger G Evans, Andrew D Cochrane, Sally G Hood, Naoya Iguchi, Bruno Marino, Rinaldo Bellomo, Peter R McCall, Nobuki Okazaki, Julian A Smith, Michael Zl Zhu, Jennifer P Ngo, Khin M Noe, Andrew Martin, Amanda G Thrift, Yugeesh R Lankadeva, Clive N May |
Journal | Perfusion
(Perfusion)
Vol. 37
Issue 6
Pg. 624-632
(09 2022)
ISSN: 1477-111X [Electronic] England |
PMID | 33977810
(Publication Type: Journal Article)
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Chemical References |
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Topics |
- Acute Kidney Injury
- Animals
- Cardiopulmonary Bypass
- Humans
- Hypoxia
- Kidney Medulla
(blood supply)
- Oxygen
- Sheep
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