MEASUREMENT OF CARDIAC OUTPUT IN NORMAL CALVES

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The calf has been used extensively as a model for in vivo testing of various total artificial hearts (TAHs) and ventricular assist devices (VADs). However, the physiologic range of resting and exercise cardiac output in 80 to 150 kg calves is not well documented. Such information would allow researchers to appreciate the constraints of the animal model used and of the devices being tested. Three calves under sedation were instrumented with an Edwards Vigilence® Continuous Cardiac Output (CCO) [Edwards Critical Care, Irvine CA] catheter connected to the CCO monitor while in their stanchion. Upon reversal of the sedative, the calves were allowed to return to a normal alert state indicated by behavioral signs such as eating, drinking, and eructating. Cardiac output (CO) measurements were taken every hour for a 24-hour period, as the animal was standing or lying down. The body surface area (BSA) was calculated from the empirical formula: BSA (m2)=0.105 x Weight (kg)0.667. CO was collected and cardiac index (CI) was calculated by normalizing CO with BSA. The results were as follows:TableThere was no difference in CO in relation to whether the calf was standing or lying down, possibly due to the stanchion limiting the animal's mobility in either position. This study provides information regarding the physiologic values of CO in conscious calves at rest. Further experiments are under way to expand the limited sample size of the present study and to investigate the CO ranges under various states of physical exertion (standardized treadmill test).