Perioperative Serum Free Hemoglobin and Haptoglobin Levels in Valvular and Aortic Surgery With Cardiopulmonary Bypass: Their Associations With Postoperative Kidney Injury
Abstract
Highlights
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Hemolysis due to CPB leads to an increase of serum free Hemoglobin(fHb) level.
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Increase of serum fHb level had an independent association with postoperative AKI.
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Hemolysis due to CPB leads to a decrease of serum Haptoglobin(Hp) level.
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Decrease of serum Hp level had an independent association with postoperative AKI.
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It might be possible to prevent postoperative AKI by attenuating the increase of fHb.
Objective
To observe the perioperative free hemoglobin and haptoglobin levels and to assess their associations with the risk of postoperative acute kidney injury (pAKI) in adult patients undergoing valvular and aortic surgery requiring cardiopulmonary bypass (CPB).
Design
A single-center, prospective, observational study.
Setting
Public teaching hospital.
Participants
The study comprised 74 adult patients without chronic renal failure who underwent cardiovascular surgery requiring CPB from 2014 to 2020.
Measurements and Main Results
Perioperative free hemoglobin and haptoglobin levels during the study period were obtained from study participants. The primary outcome was pAKI defined by the Kidney Disease: Improving Global Outcomes criteria. Of the 74 patients in this study, pAKI occurred in 25 patients (33.8%). The free hemoglobin level began to increase after the initiation of CPB and reached a peak level at 30 minutes after weaning from CPB. It returned to the baseline level on postoperative day one. Haptoglobin levels were the highest after anesthesia induction and decreased continuously until postoperative day one. In the multivariate analysis, maximum free hemoglobin and minimum haptoglobin were associated independently with increased risk of pAKI (adjusted odds ratio 1.33 [95% confidence interval 1.12-1.58; p = 0.001] and 0.95 [95% confidence interval 0.91-1.00; p = 0.03], respectively). The free hemoglobin level began to have an independent association with pAKI at one hour after commencement of CPB, and the independent association disappeared at postoperative day one.
Conclusions
This study found that the perioperative increase of the free hemoglobin level and the decrease of the haptoglobin level had independent associations with the risk of pAKI.