Capillary refill is used to assess which aspect of circulation in some assessments?

• A. Central perfusion
• B. Blood viscosity
• C. Peripheral perfusion
• D. Lung diffusion capacity

Answer: (C)

Capillary refill measures peripheral perfusion—the speed of blood flow to the small vessels in the extremities. When you press on a nail bed and then release, the time it takes for color to return reflects how well distal tissues are being perfused by the microcirculation. A normal refill time (typically under about 2 seconds in adults; a bit longer in young children) suggests adequate peripheral blood flow, while a delayed refill can indicate reduced peripheral perfusion due to factors like dehydration or shock. This assessment focuses on the circulation to the periphery, not central perfusion to core organs, and it does not inform on blood viscosity or the lungs’ diffusion capacity. Environmental temperature and other factors can affect the reading, so interpret it in the broader clinical context.