Final answer:
Capillary punctures are utilized in adults to collect small blood samples for analysis, particularly when less invasive or more practical methods are required. They are commonly used for tests like blood glucose monitoring.
Step-by-step explanation:
Capillary punctures are used in adults for medical analysis when only a small volume of blood is needed, or when venous access is difficult. This method involves collecting blood through capillary action, where blood flows into a small diameter glass tube due to the natural physics of fluid movement in narrow spaces. Capillary punctures are especially useful in situations where it's less invasive or more practical than venipuncture, such as with patients who have fragile veins or are severely dehydrated.
Certain tests, like blood glucose monitoring or point-of-care testing, typically use capillary blood. In contrast, invasive methods like catheter insertion are reserved for critical situations, such as during surgery or intensive care, where continuous blood pressure monitoring is necessary. This process involves threading thin tubes into specific locations to measure pressures transmitted to external devices—a much more intricate and invasive procedure compared to capillary punctures.