[Noninvasive determination by Doppler flow velocity recording of changes in peripheral resistance during epidural anesthesia].

Using bidirectional CW Doppler flowmetry, transcutaneous recordings of flow velocity pulses were performed on the femoral artery of 11 patients before and during peridural anaesthesia. Compared to those obtained before peridural injection of bupivacaine the pulse contours exhibited characteristic changes 10 min after the injection. The backward flow wave during diastole decreased or disappeared. There was a marked increase in the steady flow at the expense of the pulsatile flow peaks. 20 min after injection these changes were slightly more pronounced. These phenomena can theoretically be explained by the alteration in pulse wave transmission in the arterial system caused by the diminished peripheral resistance. From the results it can be concluded that ultrasonic Doppler flowmetry is a reliable method, suitable for recording the influence of regional anaesthesia on peripheral haemodynamics.