University New South Wales
Prince of Wales Hospital
Introduction: Acute kidney injury (AKI) after cardiac surgery is common. Animal studies suggest pretreatment protective effect with dexmedetomidine (Dex) in contrast and septic induced nephropathy. We aim to assess the safety and efficacy of perioperative Dex infusion in reducing AKI after on-pump cardiac surgery.
Hypothesis: Adjunct intraoperative Dex infusion mitigates kidney injury after on-pump cardiac surgery.
Methods: Prospective parallel observational study. Sequential patients having cardiac surgery by the same surgeon (June 2011- March 2012) on the same weekday were included. Patients were excluded if < 18 years old, having salvage surgery or dialysis dependent. Based on anesthesia choice, patients were divided into DEX (n=76) and Standard Anesthesia (SAC n=77) group. Dex (0.7mcg/hg/hr) was infused from induction of anesthesia and continued till extubation in ICU. Main safety outcomes were pacing and inotrope usage and main efficacy outcome was AKI (Acute Kidney Injury Network, Creatinine (Cr) rise > 26.5 µmol/l or >150%) within 5 days after surgery.
Results: DEX patients had more preoperative chronic kidney disease stage 3-5, 78.9% vs 61% (P=0.003), higher mean (SD) Cr 110(82) vs 91(36) µmol/l (P=0.02), lower glomerular filtration rate (eGFR) 66(20) vs 74(15.5) ml/min/m2 (P=0.03) and had more valve/combined surgery 39.5% vs 23.4% (P=0.03) compared to SAC patients. Mean (SD) bypass time 111(39) vs 107(31) and cross clamp time 80(37) vs 78(25) min was comparable. Comparable number of patients needed pacing at end of bypass (27% vs 22%). Post-op dobutamine use in the DEX vs SAC 69.7% vs 55.3% (P=0.06) & norepinephrine 38.1% vs 47.6% (P=0.3) was comparable. Incidence of post-op AKI was significantly lower in the DEX vs SAC group 10(13.1%) vs 21(27.3%), (OR 0.40, 95% Confidence 0.17- 0.92, P=0.03). Using logistic regression adjusting for baseline covariates age, pre-op Cr and eGFR, DEX treatment was associated with reduced post-op AKI (OR 0.43, 95%CI 0.18-1.04, P=0.06). Shorter mean (SD) ventilation time was seen in the DEX vs SAC 12.5(7.4) vs 15.5(10.3) hrs, P=0.04.
Conclusions: The addition of Dex as an adjunct to anesthesia in cardiac surgery may have a reno-protective effects and merits further investigation