Question

Why is having the patient's temperature at time of draw so important for the results of the ABG? What analytical factors can/will affect the quality of the analysis/results? Why is arterial blood preferred over venous blood for blood gas and pH analysis?

Answer 1

Need of checking patient temparature in ABG analysis

     The process of blood gas and pH measurement involves preheating the arterial blood sample to normal body temperature (37 °C) prior to measurement of pH, partial pressure of oxygen (pO₂) and partial pressure of carbon dioxide (pCO₂). This ensures that results reflect in vivo temperature condition.

The solubility of oxygen and carbon dioxide is increased at low temperatures. As a result, there is controversy about how arterial blood gases(ABG) should be interpreted in patients with altered body temperature, with hypothermia being most clinically relevant.

Factors influencing ABG result

• collection of demographic data (incorrect patient identification number, name, sex, or ordering physician);
• patient conditions (position, activity, ventilator settings, oxygen, and delivery device);
• failure to observe (recent suction, ventilator changes, or repositioning);
• sample sites (site location and manner of sampling, such as line versus puncture);
• sample error (venous sampling, air bubbles, flush solution, or heparin); and
• delayed analysis.

Importance of taking arterial blood for ABG& pH analysis

An arterial blood gas (ABG) test measures the acidity (pH) and the levels of oxygen and carbon dioxide in the bloodfrom an artery. This test is used to check how well your lungs are able to move oxygen into the blood and remove carbon dioxide from the blood. So the levels of blood gases are acurately measured in arterial blood.