The D5W injection enters the right atrium and lowers the right atrial blood temperature. The cooler right atrial blood is ejected to the pulmonary artery, where the temperature change is detected by the thermistor in the pulmonary artery. Based on this information, the cardiac output program can calculate the amount of blood pumped per minute for a given temperature change over time. The computation constant varies according to the catheter style, volume of injectate to be used, and temperature of injectate solution. Use of the correct computation constant is essential to ensuring accurate results.
Cardiac output is determined by calculating the change in temperature over the change in time.
Unless the cardiac output is extremely high or low, room temperature is usually a strong enough temperature signal for the determination of accurate cardiac output values. Cold injectate is the standard in CCTC because it is easy to keep the injectate temperature within the desired range. Due to seasonal fluctuations in environmental temperature, it is often difficult to maintain the injectate temperature within the room temperature range. Procedure Rationale 2. The injectate probe is connected between the blue injectate port and the double barreled syringe.