Acute kidney injury (AKI) after cardiac surgery is associated with increased mortality and morbidity. The AKI criteria used in the study is a slight modification (72 hours instead of 48 hours) of the consensus report from the Acute Kidney Injury Network. AKI is defined as an abrupt increase in s- creatinine >26.5 µmol/L (0.3mg/dL), or a relative increase in s-creatinine > 50%, or a decrease in urine output to < 0.5 ml/kg/h for more than 6 h within the first postoperative day. We recently found that high thoracic epidural analgesia (HTEA) was associated with a decreased frequency of postoperative dialysis. The purpose of this study was to evaluate TEA on renal function expressed as postoperative changes in s-creatinine, with the hypothesis that HTEA improves renal function. Sixty low to moderate risk patients scheduled for elective coronary artery bypass grafting with or without aortic valve replacement were randomised to receive HTEA as supplement to general anaesthesia (GA).
Results: Serum-creatinine was lower in HTEA patients in the first 72 hours after surgery (P=0.018, 2-way ANOVA), with overall maximal increase 12.1% vs. 23.8%. The incidence of AKI was, although not significantly, lower (13.3% vs. 36.7%, P=0.074, χ2-test). Use of inotropes, constrictors and vasodilators had no impact on development of AKI.
Conclusion: HTEA as a supplement to GA in cardiac surgery is followed by a less increase in s-creatinine in the first 72 hours after surgery and a tendency towards lower incidence of AKI. The finding of a possibly kidney-protective effect of HTEA could be of clinical importance and warrants further investigation.
Keywords: Acute kidney injury, high thoracic epidural analgesia, haemodynamics, constrictors