Timing of continuous veno-venous hemodialysis in the treatment of acute renal failure following cardiac surgery.

The purpose was to study optimum timing of continuous veno-venous hemodialysis (CVVHD) for acute renal failure (ARF) after cardiac surgery. CVVHD was performed in two groups [elapsed time between urine output (UO) <0.5 ml/kg/h and dialysis of no more than 12 h in group A and >12 h in group B] with a total of 58 adult patients. Survivors in groups A and B were entered into groups A₁ and B₁, respectively. Compared to group A, the acute physiology and chronic health evaluation III score, peak values of urea and creatinine before CVVHD, major complications, period of ICU and hospitalization were significantly higher in group B. In-hospital mortality in group B was significantly higher than that in group A (37.5 vs. 8.8%, p = 0.02). Kaplan-Meier curves confirmed significantly better postoperative survival in group A (χ² = 6.966, p = 0.008). Time elapse from UO < 0.5 ml/kg/h until dialysis among the survivors was significantly lower than that among the dead (12.0 ± 6.2 vs. 20.8 ± 9.1 h, p = 0.0002). Additionally, duration of dialysis, length of ICU stay, duration of ventilator support and time elapse from dialysis until UO > 1 ml/kg/h were significantly higher in group B₁ as compared to those in group A₁. All of them correlated positively with the time elapse from UO < 0.5 ml/kg/h until dialysis. Early beginning of CVVHD is extremely important.