There is an order to obtain a blood sample from a neonate. It is determined that you should obtain the sample from a capillary instead of the artery. Which of the following is true regarding a capillary blood gas sample?

You must be familiar with the heel-stick procedure in infants in order to get this one correct.

The lateral aspect of the heel is the most common site for collecting a capillary blood sample in infants. After you puncture the infant’s heel, you should wipe away first drop of blood and observe for free flow before collection. You do not need to squeeze the heel.

Because the infant’s arteries are so tiny, it’s very difficult to stick them with a needle. So that is why we use capillary blood from the heel instead. But there are some differences in the ABG values of capillary blood when compared to arterial blood. And you must know these difference for the TMC Exam.

Capillary blood correlates well with the pH and PaCO2 values of arterial blood. Therefore, it is useful ONLY for assessing the acid-base status.

Capillary blood does not correlate well with the PaO2 values, so you should never use a capillary sample to assess the infant’s oxygenation status. So after going through all the answer choices, we can determine that the correct answer has to be C.

The correct answer is: C. The pH and PCO2 correlate well with arterial blood