Certified Respiratory Therapist Practice Exam

What temperature is used to “arterialize” the capillary blood in PcO2 and PO2 electrodes?

1. 38 degrees Celsius

2. 40 degrees Celsius

3. 42 degrees Celsius

4. 44 degrees Celsius

The correct answer is: 44 degrees Celsius

To "arterialize" the capillary blood in partial pressure of oxygen (PcO2) and partial pressure of carbon dioxide (PO2) electrodes, a higher temperature, specifically 44 degrees Celsius, is used. This elevated temperature is significant because it helps to increase the solubility of gases in the blood sample, enhancing the diffusion of oxygen into the plasma from the cells within the capillaries. As the temperature rises, the kinetic activity of the gas molecules increases, allowing for improved interaction with the electrode and more accurate readings of the partial pressures of oxygen and carbon dioxide. Using a temperature of 44 degrees Celsius is a standard practice in capillary blood gas analysis to mimic conditions closer to those found in arterial blood, making it possible to obtain results that reliably represent the true oxygenation and ventilation status of the patient. The choice of a lower temperature would not facilitate the same level of gas exchange and might lead to less accurate measurements.