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Reversal of renal tissue hypoxia during experimental cardiopulmonary bypass in sheep by increased pump flow and arterial pressure
Author(s) -
Lankadeva Yugeesh R.,
Evans Roger G.,
Cochrane Andrew D.,
Marino Bruno,
Hood Sally G.,
McCall Peter R.,
Iguchi Naoya,
Bellomo Rinaldo,
May Clive N.
Publication year - 2021
Publication title -
acta physiologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.591
H-Index - 116
eISSN - 1748-1716
pISSN - 1748-1708
DOI - 10.1111/apha.13596
Subject(s) - cardiopulmonary bypass , pulsatile flow , mean arterial pressure , anesthesia , medicine , renal blood flow , blood pressure , hypoxia (environmental) , cardiology , hemodynamics , chemistry , oxygen , heart rate , organic chemistry
Aim Renal tissue hypoxia during cardiopulmonary bypass could contribute to the pathophysiology of acute kidney injury. We tested whether renal tissue hypoxia can be alleviated during cardiopulmonary bypass by the combined increase in target pump flow and mean arterial pressure. Methods Cardiopulmonary bypass was established in eight instrumented sheep under isoflurane anaesthesia, at a target continuous pump flow of 80 mL·kg −1 min −1 and mean arterial pressure of 65 mmHg. We then tested the effects of simultaneously increasing target pump flow to 104 mL·kg −1 min −1 and mean arterial pressure to 80 mmHg with metaraminol (total dose 0.25‐3.75 mg). We also tested the effects of transitioning from continuous flow to partially pulsatile flow (pulse pressure ~15 mmHg). Results Compared with conscious sheep, at the lower target pump flow and mean arterial pressure, cardiopulmonary bypass was accompanied by reduced renal blood flow (6.8 ± 1.2 to 1.95 ± 0.76 mL·min −1 kg −1 ) and renal oxygen delivery (0.91 ± 0.18 to 0.24 ± 0.11 mL·O 2 min −1 kg −1 ). There were profound reductions in cortical oxygen tension (PO 2 ) (33 ± 13 to 6 ± 6 mmHg) and medullary PO 2 (31 ± 12 to 8 ± 8 mmHg). Increasing target pump flow and mean arterial pressure increased renal blood flow (to 2.6 ± 1.0 mL·min −1 kg −1 ) and renal oxygen delivery (to 0.32 ± 0.13 mL·O 2 min −1 kg −1 ) and returned cortical PO 2 to 58 ± 60 mmHg and medullary PO 2 to 28 ± 16 mmHg; levels similar to those of conscious sheep. Partially pulsatile pump flow had no significant effects on renal perfusion or oxygenation. Conclusions Renal hypoxia during experimental CPB can be corrected by increasing target pump flow and mean arterial pressure within a clinically feasible range.