Noninvasive monitoring of renal blood flow characteristics during acute renal failure in man.

Duplex Doppler ultrasound (DDU) was used to study the blood flow characteristics of the renal interlobar artery in 20 subjects with acute renal failure (ARF), 14 subjects with transient impairment of renal function and 23 control subjects with normal function. Renovascular resistance was assessed by pulsatility index (PI) and change in flow velocity by change in mean frequency shift (delta f). The 99% confidence intervals for PI in the three groups were 3.32-5.46, 1.58-2.34 and 0.99-1.33 respectively. Values for delta f were 0.2-0.38, 0.5-0.62 and 0.7-1.02 kHz respectively. Ten ARF patients recovered function, 99% confidence intervals for PI just prior to recovery were 0.9-1.48 and for delta f 0.52-1.02 kHz. There was increased renovascular resistance and reduced intrarenal blood flow velocity at the onset of ARF. These changes persisted during ARF; recovery of function occurred after they returned to normal. Similar, but less marked, changes were found in patients with a transient impairment of function.