Doppler evaluation of renal blood flow velocity as a predictive index of acute renal failure in perinatal asphyxia

Aim of our study was to evaluate Doppler renal blood flow velocity in asphyxiated neonates and to correlate renal function to Doppler findings. Doppler renal blood flow velocity was evaluated in 23 severely asphyxiated neonates born at a gestational age > 32 weeks and compared to our standard Doppler data obtained in 25 healthy neonates comparable for gestational age and birth weight. Renal Doppler ultrasound was performed on the 1st and 3rd days of life. Renal function was investigated in the first 2 weeks of life. Asphyxiated neonates showed mean values of systolic velocity and mean velocity significantly reduced (P < 0.001) compared with our standard Doppler values on the 1st day of life. Seven out of the 23 asphyxiated neonates were affected by acute renal failure and 14 showed no renal involvement. Two neonates were oliguric but did not develop acute renal failure. On the 1st day of life, neonates with acute renal failure had significantly lower mean values of systolic velocity and mean velocity than the asphyxiated neonates without renal involvement (P < 0.01). All 7 neonates affected by acute renal failure showed a systolic velocity more than 2SD below the mean standard value, while only 4 of the 16 asphyxiated neonates (25%) without acute renal failure had low systolic velocity values on the 1st day of life. Doppler velocities in asphyxiated neonates were similar to standard values on the 3rd day of life. Renal failure recovered before the 11th day of life in all cases. Our findings indicate that decreased Doppler renal flow systolic velocity observed in asphyxiated neonates on the st day of life is a useful predictive index for subsequent development of acute renal failure, with 100% sensitivity and 63.6% specificity.