An arterial blood gas sample is drawn from a patient on room air at 12:00 and received in the lab at 12:10. The MLT notices there is an air bubble present, expels it and runs the sample. How will this compare to the patient's true physiological state?

Prepare for the CAMLPR Specimen Collection Competency Test. Practice with diverse question sets including multiple-choice and flashcards. Each question includes hints and explanations to help you become proficient before the exam.

An air bubble in an arterial blood gas sample allows gas exchange with the ambient air inside the bubble. Ambient air has a high oxygen level and essentially no carbon dioxide. Oxygen diffuses from the bubble into the blood, while carbon dioxide diffuses from the blood into the bubble. This shifts the blood’s measured values away from the patient’s true physiology: pO2 goes up, pCO2 goes down, and the pH rises (less acidic) because CO2, a key determinant of acidity, is lost to the bubble. Even if the bubble is expelled before testing, the diffusion that occurred while the bubble was present has already altered the sample, so the results will still reflect these changes.