Pulsatile cardiopulmonary bypass and renal function in elderly patients undergoing aortic valve surgery

OBJECTIVES: To evaluate if pulsatile cardiopulmonary bypass (CPB) has any protective influence on renal function in elderly patients undergoing aortic valve replacement (AVR). METHODS: Forty-six patients (≥75 years old) with aortic valve stenosis underwent AVR with either pulsatile perfusion (PP) or non-pulsatile perfusion (NP) during CPB. Haemodynamic efficacy of the blood pump during either type of perfusion was described in terms of the energy equivalent pressure and the surplus haemodynamic energy. Urine samples were collected before surgery, at sternum closure, and at 2 and 18 h of intensive care unit stay to detect acute kidney injury markers. Perioperative urine levels of N-acetyl-β-D-glucosaminidase (NAG), kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin (NGAL) were assessed together with plasma creatinine, creatinine clearance (CCr) and 24-h haemodynamic monitoring. Normally distributed continuous variables were described as mean ± standard deviation and non-normally distributed data were presented as the median [25th–75th percentiles]. RESULTS: PP was characterized by a significantly higher amount of surplus haemodynamic energy transferred to the patients (P<0.001), with lower mean systemic vascular resistance during CPB (P=0.020) and during 18 h postoperatively (group-P=0.018). No difference was found between pre- and postoperative CCr in the PP group (71±23 vs 60±35 ml/min, P=0.27), while its statisticallysignificant perioperative decrement was observed in the NP group (67±24 vs 45±15 ml/min, P<0.001). The PP group showed significantly lower urinary levels of NAG at 18 h postoperatively (P=0.008), and NGAL at sternum closure (P=0.010), 2 h (P<0.001) and 18h( P=0.015) postoperatively. CONCLUSIONS: Short-term PP in elderly patients showed higher safety for renal physiology than NP, resulting in better maintenance of glomerular filtration and lower renal tissue injury.