Experience with renal failure during extracorporeal membrane oxygenation: treatment with continuous hemofiltration

We use extracorporeal membrane oxygenation (ECMO) to treat respiratory and cardiac failure in children who are unresponsive to standard ventilator and pharmacologic management. All patients have cardiac and abdominal ultrasonography prior to ECMO to identify major structural anomalies and anatomically normal kidneys. Despite this, oliguric renal failure is seen in a number of patients. Acute renal failure (ARF) developed in two of the first 20 patients we placed on ECMO and both of these patients died. Six of the last 27 patients (22%) also developed ARF and were treated with continuous hemofiltration (CH) placed in-line with the extracorporeal circuit. The technique of CH removes plasma water and dissolved solutes while retaining proteins and cellular components of the intravascular space. The duration of CH ranged from 9 to 112 hours (mean 57.5 hours). Indications for CH were hypervolemia, hyperkalemia, and azotemia. The mean serum potassium prior to CH was 5.6 (range 4.3 to 7.0) compared with 4.5 after filtration. We filtered 5 to 10 mL/kg/h and replaced it with crystalloid chosen on the basis of serum and filtrate electrolytes. These six patients had a 33% mean weight gain prior to CH. We were able to remove as much as 2,200 g in the most edematous patient with significant improvement in cardiopulmonary status. Four of the patients on CH died of their primary pulmonary or cardiac disease without specific problems related to ARF. The other two patients were successfully weaned from ECMO, extubated, and have not needed further therapy for renal failure. We conclude that CH is useful in managing the complications of oliguric renal failure during ECMO.