Q When using the thermodilution method for cardiac output measurements, what temperature difference in degrees Celsius is required for accuracy? When we have a patient on the therapeutic hypothermia protocol and are using the thermodilution method for calculating cardiac output, the patient’s temperature may be as low as 32°C to 33°C with the injectate at room temperature (21°C–22°C). Is this enough of a difference?

A Teresa Wavra, RN, MSN, CNS, CCRN, and Mary Kay Bader, RN, MSN, CCRN, CNRN, reply:

Thermodilution cardiac output (TDCO) is based on the principles of dilution. The TDCO method uses a known quantity of cold solution to create a thermal deficit. A bolus of sterile solution that is colder than the patient’s blood is injected through the proximal port of the pulmonary artery catheter. The solution mixes with the patient’s blood, passes the tricuspid valve through the right...

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