Acute renal failure: veno-venous haemofiltration: higher ultrafiltration rates reduce mortality

Clinical bottom line (level 1b)

  1. Critically-ill patients with acute renal failure who received continuous veno-venous haemofiltration at ultrafiltration rates of 35 or 45 mg/kg/hr compared with 20 mg/kg/hr were less likely to die (NN T = 6 at days) .
  2. There was no clear difference in mortality between the 35 and 45 mg/kg/hr groups.
  3. There was no clear difference in complications between the three groups.
Ronco et al: Lancet 2000; 355 : 26-30
Expires October 2003

The study

Unblinded ?concealed randomised trial with intention-to-treat
Setting: 2 intensive care units, Italy

425 patients (aged , 56% male) admitted to an intensive care unit with acute renal failure (abnormal concentrations of blood urea and creatinine, and urine ouput of < 200 ml in the preceding 12 hours despite adequate fluid resuscitation and furosemide administration.
Note:
  • Most patients had Swan-Ganz cathethers inserted to monitor haemodynamic status.
  • Haemofilters were changed every 24 hours - filtration dose was calculated using the patient's preadmission body weight.

Control Group: (n = 146, 146 analysed): continuous veno-venous haemofiltration at 20 ml/kg/hr
Experimental Group: (n = 139, 139 analysed): continuous veno-venous haemofiltration at 35 ml/kg/hr
Experimental Group: (n = 140, 140 analysed): continuous veno-venous haemofiltration at 45 ml/kg/hr

100% followed for 15 days

The evidence

35 ml/kg/hr v. 20 ml/kg/hr
Outcome Time to outcome CER EER RRR
(95% CI)		 ARR
(95% CI)		 NNT
(95% CI)
death days 86
(58.9%)		 43.2
(%)		 27%
(7% to 42%)		 15.7%
(4.27% to 27.2%)		 6
(4 to 23)

45 mg/kg/hr v. 20 mg/kg/hr
Outcome Time to outcome CER EER RRR
(95% CI)		 ARR
(95% CI)		 NNT
(95% CI)
death days 86
(58.9%)		 59
(42.1%)		 28%
(9% to 44%)		 16.8%
(5.33% to 28.2%)		 6
(4 to 19)

Comments

  1. No significant difference in mortality was noted between the 35 and 45 mg/kg/hr groups.
  2. 90% to 95% of patients who survived had full recovery of renal function.
  3. Complication rates were similar between the 3 groups (bleeding 5%; vascular access malfunction 11%; repeated filter clotting 3%).
  4. Patients received haemofiltration for an average of 12 days.
  5. No study has yet shown that continuous veno-venous haemofiltration is better or safer than haemodialysis.

Citation

  1. Ronco C, Bellomo R, Homel P, et al: effects of different doses in continuous veno-venous haemofiltration in outcomes of acute renal failure: a prospective randomised trial. Lancet 2000; 355 : 26-30
Search Terms: from ACP Journal Club
Contributor: Chris Ball, October 2001
Reviewer: Clare Wotton

Clinical Question.
Patient critically-ill with acute renal failure
Intervention or Exposure continuous veno-venous haemofiltration (CVVH) at various ultrafiltration rates
Outcome death