Pulsed-Doppler evaluation of renal perfusion during pulsatile extracorporeal circulation. A pilot study

Acute renal failure (ARF) after cardiac surgery is a risk factor associated with mortality and use of resources. Some studies have reported beneficial effects of pulsatile flow on cardiopulmonary bypass (CPB) on renal function. The aim of this study is to describe the echographic morphology of the renal arterial wave modifying the parameters of pulsatile CPB.

Descriptive study was performed on 10 patients without previous AFR and undergoing cardiac surgery with CPB. Pre-, intra- and post-surgery renal ultrasound was performed. During pulsatile CPB, the amplitude and the baseline flow were modified. Recordings of pulsed Doppler in intrarenal arteries were obtained by measuring maximum systolic velocity, minimum diastolic velocity, resistance index (RI) and acceleration time (AT).

Statistical differences were found in ultrasounds pre-CPB between A50F50 modality (P=.013), A50F30 (P=.013) and A60F50 (P=.003). No statistically significance was found with A30F30 modality (P=.125).

The decrease in the amplitude and the baseline flow of pulsatility during CPB shows a renal ultrasound morphology that is more similar to the physiological one. Subsequent studies using these characteristics during pulsatile CPB could thus show perfusion over the ARF that occurs after cardiac surgery.