Mean perfusion pressure in cardiopulmonary bypass as a factor of intraoperative acute kidney injury

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The OBJECTIVE was to evaluate the role of mean perfusion pressure in the development of acute kidney injury (AKI) in patients operated with CPB.METHODS AND MATERIALS. A retrospective monocenter observational study was conducted among patients CPB (n=97) who underwent planned heart surgery using CPB. Inclusion criteria: age over 18 years, duration of surgery from 90 to 180 minutes, no signs of end-stage renal disease. The group was divided into subgroups according to the level of mean perfusion pressure (MPP): 1st – MPP<60 mmHg, 2nd – MPP equal to and >60 mmHg. Diagnosis of AKI was carried out on the basis of changes in serum creatinine and biomarkers (NGAL, IgG, albumin in urine). The studied parameters were recorded 15 minutes after the start and end of general anesthesia as well as 24 and 48 hours after surgery.RESULTS. In the 1st subgroup, the frequency of AKI was higher: after 24 hours – 48 (78.7 %), in the 2nd subgroup – 10 (27.8 %), and after 48 hours – 21 (34.4 %) and 5 (13.9 %), respectively. In the 1st subgroup, the need for renal replacement therapy was 5 (8.2 %), while in the 2nd subgroup only 1 patient needed renal replacement therapy (2.8 %). Also, in the 1st subgroup, a higher level of lactate was detected at the end of general anesthesia – the median in the 1st subgroup was 4.6 mmol/l (2.5–11.6), in the 2nd – 2.5 mmol/l (1.4–7.2) (p= 0.022). The levels of AKI biomarkers in urine after 24 hours also differed: NGAL in the 1st – 473.1 ng/ml (235.7–749.5) and in the 2nd –111.3 ng/ ml (53.4–152.9) (p=0.003), albumin 174.6 mg/l (151.2–236.9) and 35.8 mg/l (21.3–52.5) respectively (p=0.006), IgG – 61.7 mg/l (24.9–88.5) and 9.7 mg/l (7.1–14.4) (p=0.002).CONCLUSION. Mean perfusion pressure is an important indicator of the adequacy of cardiopulmonary bypass. Lowering it below 60 mmHg leads to hypoperfusion of the kidneys with the risk of acute kidney injury.