To check blood circulation in the injured limb, you press and release the fingernail on the finger of the injured limb and conclude that blood circulation is impaired because :
Explication
The English prompt diverges from the source editions: they check capillary refill below the bandage, and the accepted source response identifies delayed return of the nail bed's pink colour. Slow refill beyond the dressing suggests impaired circulation, whereas pain or anxiety alone does not measure blood flow.