Which statement best describes what the thermistor does in this catheter system?

Which statement best describes what the thermistor does in this catheter system?

• A. Measures core body temperature and is used to calculate cardiac output by thermodilution.
• B. Measures ambient temperature outside the body.
• C. Measures skin temperature to estimate CO.
• D. Detects heart rate directly to derive CO.

Answer: (A)

In this context, the sensor in the catheter is used to measure the temperature of the blood as a cold saline bolus passes by. That temperature-time data is then fed into the thermodilution calculation (Stewart-Hamilton) to determine cardiac output. The key point is that the thermistor is reading blood temperature in the central circulation (reflecting core blood temperature), not ambient or skin temperature, and not heart rate. More CO means the cold bolus is carried away faster, producing a smaller, quicker temperature change; less CO yields a slower, larger change. So the statement that best fits is the one describing measuring core blood temperature and using thermodilution to calculate cardiac output.

In this context, the sensor in the catheter is used to measure the temperature of the blood as a cold saline bolus passes by. That temperature-time data is then fed into the thermodilution calculation (Stewart-Hamilton) to determine cardiac output. The key point is that the thermistor is reading blood temperature in the central circulation (reflecting core blood temperature), not ambient or skin temperature, and not heart rate. More CO means the cold bolus is carried away faster, producing a smaller, quicker temperature change; less CO yields a slower, larger change. So the statement that best fits is the one describing measuring core blood temperature and using thermodilution to calculate cardiac output.