Comparison of systemic and renal hemodynamics measured by Doppler ultrasonography in canine experimental hypovolemia.

The aim of this study was to examine renal hemodynamics at the hypovolemic and recovery phases in two different hypovolemic shock models using Doppler ultrasonography, and to compare this with systemic hemodynamics. In experiment 1, the hypovolemic phase was induced in 6 mongrel dogs by removing arterial blood at 30 ml/kg for 60 min. In the recovery phase, this blood was reinfused at 30 ml/kg over 60 min. In experiment 2, hypovolemia was induced in 12 beagle dogs by rapid blood removal until blood pressure decreased to 40 mmHg and was maintained at this pressure for 30 min. Six of the dogs were then infused with 20 ml/kg hydroxyethyl starch over 5 min, and the other 6 were infused with 60 ml/kg lactated Ringer's solution also over 5 min. Parameters for systemic and renal hemodynamics were measured by using a polygraph and the Doppler method, respectively. The decrease of diastolic blood flow, resulted in an increase of vessel resistance, and was detected in the hypovolemic kidney by the Doppler method. The rapid and large volume infusion of resuscitation fluids was effective for the recovery of both systemic circulation and renal blood flow, however this induced an increase of kidney vessel resistance, a result of the autoregulation mechanism of the kidney. The changes in these parameters at the main renal artery and interlobar artery were similar.