Influence of blood haemoglobin concentration on renal haemodynamics and oxygenation during experimental cardiopulmonary bypass in sheep. (3rd December 2020)

• Record Type: Journal Article
• Authors: Lankadeva, Yugeesh R.; May, Clive N.; Cochrane, Andrew D.; Marino, Bruno; Hood, Sally G.; McCall, Peter R.; Okazaki, Nobuki; Bellomo, Rinaldo; Evans, Roger G.
• Is Part Of: Acta physiologica. Volume 231:Number 3(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-12-03
• Subjects: acute kidney injury -- blood transfusion -- cardiac surgery -- hypoxia -- renal circulation; Physiology -- Periodicals; Physiology -- Research -- Periodicals; 612
• DOI: 10.1111/apha.13583
• Languages: English
• ISSNs: 1748-1708

Abstract

Abstract: Aim: Blood transfusion may improve renal oxygenation during cardiopulmonary bypass (CPB). In an ovine model of experimental CPB, we tested whether increasing blood haemoglobin concentration [Hb] from ~7 g dL −1 to ~9 g dL −1 improves renal tissue oxygenation. Methods: Ten sheep were studied while conscious, under stable isoflurane anaesthesia, and during 3 hours of CPB. In a randomized cross‐over design, 5 sheep commenced bypass at a high target [Hb], achieved by adding 600 mL donor blood to the priming solution. After 90 minutes of CPB, PlasmaLyte ® was added to the blood reservoir to achieve low target [Hb]. For the other 5 sheep, no blood was added to the prime, but after 90 minutes of CPB, 800‐900 mL of donor blood was given to achieve a high target [Hb]. Results: Overall, CPB was associated with marked reductions in renal oxygen delivery (−50 ± 12%, mean ± 95% confidence interval) and medullary tissue oxygen tension (PO2, −54 ± 29%). Renal fractional oxygen extraction was 17 ± 10% less during CPB at high [Hb] than low [Hb] ( P = .04). Nevertheless, no increase in tissue PO2 in either the renal medulla (0 ± 6 mmHg change, P > .99) or cortex (−19 ± 13 mmHg change, P = .08) was detected with high [Hb]. Conclusions: In experimental CPB blood transfusion to increase Hb concentration from ~7 g dL −1 to ~9 g dL −1 did not improve renal cortical or medullary tissue PO2 even though it decreased whole kidney oxygen extraction.