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

Cardiac index is a criterion associated with cardiac output that measures the volume of blood pumped over time to the animal’s body surface area. Cardiac index is considered the reference standard parameter for targeting organ perfusion and oxygen delivery in shock.

For this purpose, ten mixed-breed male dogs ranging in age from 1.5 to 3.5 years 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 additional 30 minutes under hypovolemic condition. The dogs were then randomly divided into two equal groups, each group was resuscitated with Ringer's lactate solution (20 ml/kg) or 6% hydroxyethyl starch (5 ml/kg) over four 15-min intervals.

Hypovolemic shock caused significantly 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.

According to the findings of the present study, it can be concluded that echocardiographic evaluation of cardiac index is an easy, affordable and reliable method to diagnose hypovolemia and monitor patients' response to fluid therapy.Conflict of interest: None declared.