Original scientific paper

Subclinical kidney injury after exposure to cardiopulmonary bypass: comparison of mild and moderate hemodilution

Mirabel Mažar ; Clinic for anesthesiology, reanimatology, intensive care and pain therapy; University clinical hospital centre Zagreb, Zagreb, Croatia
Anita Lukić ; Department for anesthesiology, reanimatology and intensive care; Varaždin general hospital, Varaždin, Croatia
Krešimir Reiner ; Clinic for anesthesiology, reanimatology, intensive care and pain therapy; University clinical hospital centre Zagreb, Zagreb, Croatia
Sanja Konosić ; Clinic for anesthesiology, reanimatology, intensive care and pain therapy; University clinical hospital centre Zagreb, Zagreb, Croatia
Željko Čolak ; Clinic for anesthesiology, reanimatology, intensive care and pain therapy; University clinical hospital centre Zagreb, Zagreb, Croatia

Abstract

Introduction: Frequency of clinically manifesting kidney injury after all types
of heart surgery involving cardiopulmonary bypass ranges between 1 % and 5
% and frequency of subclinical kidney injury is even higher but can be almost
impossible to detect in the early postoperative period by using traditional biomarkers.
Alpha-1-microglobulin (A1M) and lipocalin associated with neutrophil
gelatinase (NGAL) are potential early urine biomarkers of subclinical
kidney injury. We hypothesized that moderate hemodilution with priming
solution during cardiopulmonary bypass reduces kidney injury, which was determined
by using A1M and NGAL, together with traditional serum biomarkers
urea and creatinine.
Methods: Total of 158 participants scheduled for elective heart surgery involving
cardiopulmonary bypass were included in the study and divided
into two groups by the degree of hemodilution during surgery, which was
defined by ratio of intraoperative and postoperative hematocrite: mild hemodilution
group (ratio ≥ 60 %) and moderate hemodilution group (ratio
< 60 %).
Results: Biomarkers of kidney injury, A1M and NGAL, increased in all patients
that underwent elective heart surgery involving cardiopulmonary bypass.
Mild and moderate hemodilution group showed significant differences
in absolute values of A1M at five hours after surgery (p = 0.029), as well as
in the ratio of A1M (A1M 24 hours after surgery/A1M before surgery) (p =0.023). No differences between the two groups were found for biomarkers
NGAL, urea and creatinine. The transfusion dose of blood products did not
correlate with markers of kidney injury during the first 24 hours after cardiopulmonary
bypass, unlike the length of cardiopulmonary bypass, cardiac
ischemia, as well as temperature which significantly correlated with the ratios
(24 hours after surgery/before surgery) of creatinine, A1M and NGAL in not
consistent direction.
Conclusion: Moderate hemodilution had a protective effect on subclinical
kidney injury in the early period after cardiopulmonary bypass, as seen from
differences between the groups for biomarker A1M. Urea and creatinine were
not sensitive enough in detecting subclinical kidney injury shortly after cardiopulmonary
bypass, while NGAL increased, but similar in both groups.

Keywords

hemodilution; cardiopulmonary bypass; alpha-1-microglobulin (A1M); lipocalin associated with neutrophil gelatinase (NGAL); subclinical kidney injury

Hrčak ID:

351404

URI

https://hrcak.srce.hr/351404

Publication date:

7.10.2026.

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