Certified Respiratory Therapist Practice Exam

What is the suitable action to take to avoid preanalytical errors due to air contamination in a blood gas sample?

1. Analyze the sample immediately

2. Use the minimum amount of heparin

3. Store the sample at room temperature

4. Cap the syringe slowly

The correct answer is: Use the minimum amount of heparin

To avoid preanalytical errors due to air contamination in a blood gas sample, using the minimum amount of heparin is a suitable action. Heparin is an anticoagulant that helps prevent clotting during the transportation and analysis of the blood sample. However, excess heparin can cause changes in the electrolyte concentrations and pH of the sample, which could lead to inaccurate results. By using the minimum amount of heparin necessary to adequately anticoagulate the sample, it reduces the risk of dilution and potential modification of the blood’s natural state, which may occur if too much heparin is introduced or if air exposure occurs during sample handling. The other options, while relevant to the handling of blood gas samples, do not directly address the prevention of air contamination. Analyzing the sample immediately can reduce the time for contamination but may not be practical in every setting. Storing the sample at room temperature can lead to alterations in the sample's composition due to metabolic activity and should be avoided for optimal results. Capping the syringe slowly may help reduce splashing or turbulence, but it does not directly prevent air contamination from occurring during the withdrawal process or change how the sample is handled afterward.