thermodilution

Reduction in temperature in a liquid that occurs when it is introduced into a colder liquid; the volume of the latter liquid can be calculated from the amount of rise in its temperature.

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ther·mo·di·lu·tion .thər-mō-dī-'lü-shən adj relating to or being a method of determining cardiac output by measurement of the change in temperature in the bloodstream after injecting a measured amount of cool fluid (as saline)

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ther·mo·di·lu·tion (thur″mo-dĭ-looґshən) a method of measuring blood flow by injection of a known quantity of a cool or cold indicator, such as a saline solution or distilled water, into the cardiovascular system and measuring with a thermistor the temperature over time at a specific point in the system.

Thermodilution cardiac output curves. The area under the curve is inversely related to output. In the normal state, saline injection is followed by a sharp upstroke and a smooth curve with a mildly prolonged downslope to baseline. In a high cardiac output state, the saline injectate moves faster through the right side of the heart and temperature returns to baseline more quickly, reducing the area under the curve. In a low cardiac output state, the return to baseline is prolonged, increasing the area under the curve.