Evaluation of cardiac index as a criterion for termination of resuscitation with fluid therapy in dogs with hypovolemic shock.

Abstract

The cardiac index which is obtained by dividing the cardiac output on the body surface is known as the standard parameter to evaluate tissue perfusion. The purpose of this study was to evaluate cardiac index changes as a novel criterion to estimate the time of fluid therapy termination in dogs with hypovolemic shock. For this purpose, 10 mixed breed dogs were selected and after determination of body surface area, cardiac output was measured by Doppler echocardiography in eight stages. After induction of anesthesia and recording of vital signs, cardiac index evaluation was performed in control stage. Hypovolemic shock was induced by blood withdrawal to a mean arterial pressure of 40 to 50 mmHg within 30 minutes and then maintained for 30 minutes under hypovolemic condition. The dogs were then randomly divided into two equal groups; each group was resuscitated with lactated Ringer's solution (20 ml/kg) or 6% hydroxyethyl starch (5 ml/kg) over four 15-min intervals. The dogs were monitored for up to one hour from the last stage of resuscitation and at the end of each stage evaluation of cardiac index was performed. Hypovolemic shock caused significant decrease in cardiac index (2.3±0.1) compared to control stage (4.8±0.6) (p <0.05). Following resuscitation, cardiac index increased and returned to pre-shock values in both groups. Based on the results of this study, echocardiographic evaluation of cardiac index is an ideal criterion for estimating the termination of resuscitation in dogs with hypovolemic shock.