A voltage regulator is disclosed that includes first and second output transistors each outputting a current from the input terminal to the output terminal of the voltage regulator; and a control circuit part controlling the operations of the first and second output transistors to equalize a voltage proportional to an output voltage with a reference voltage. The determination of the blood flow rate accommodates injectate induced thermal influences on a dilution thermal sensor, wherein the thermal influences can occur prior to introduction of the injectate into the blood flow. A hitch adapter is affixed to the bottom portion to secure the carriage guide assembly to a vehicle hitch.