Final answer:
The normal PCWP is between 4 to 12 mm Hg, and pulmonary edema often develops when PCWP exceeds 18 to 20 mm Hg. In thermodilution cardiac output measurement, altering the temperature or the volume of the injected fluid can affect the calculated CO, potentially leading to inaccuracies.
Step-by-step explanation:
The normal Pulmonary Capillary Wedge Pressure (PCWP) is generally between 4 to 12 mm Hg and is used as an indirect measure of left atrial pressure. Pulmonary edema, which is the accumulation of fluid in the alveoli and lung interstitium, can develop when PCWP exceeds 18 to 20 mm Hg, as this increased pressure can lead to fluid crossing the capillary endothelium into the interstitial and alveolar spaces.
The effect of changes in thermodilution fluid temperature on cardiac output measurement is based on the principle that the temperature change detected downstream is inversely proportional to the flow. Therefore, changing the temperature of the injected fluid can affect the temperature gradient measured, and thus the accuracy of the CO calculation.
Similar principles apply to the volume of injection; a decreased volume of injection may lead to a less pronounced thermal change and potentially underestimation of cardiac output. Medical professionals must carefully standardize these parameters to ensure accurate CO measurements during thermodilution procedures.