A prospective analysis of creatinine clearance during ECMO and ultrafiltration

Ultrafiltration (UF) during neonatal ECMO was shown not to impair renal function in our retrospective review of 17 patients from 1986-1988. Creatinine production (UV) was assumed to be 10 mg/kg/day for creatinine clearance (CrCl) calculations. To validate this assumption and to better understand renal function during ECMO, CrCl was measured prospectively on 27 non-surgical neonates. Seven patients required hemofiltration for fluid management. Typical UF rates were 3-10ml/kg/hour. Two patients were excluded from analysis secondary to pre-existing renal disease. Renal CrCl was defined as UV/P where U=urine creatinine (mg/dl/24h), V=urine volume (ml/24h) and P=plasma creatinine (mg/dl). In 20 control patients who did not receive UF, UV or creatinine excretion was 11.6+0.4mg/kg/24h (mean+SEM). No significant change over time was seen in mean CrCl of the control group. The UF group, however, demonstrated a steady decrease in mean CrCl. CrCl on the fourth day before the start of UF was significantly higher (P=0.05) than day three of UF. In conclusion: 1) the assumption of UV used in the retrospective study was supported; 2) CrCl decreases during UF; 3) the consistency of CrCl in the control population suggests no alteration in glomerular filtration during ECMO runs of 3-8 days.