Final answer:
The grade of pedal edema that shows an 8 mm indentation lasting more than 2 minutes is Grade 3, which is a severe form of fluid accumulation and usually requires medical attention.
Step-by-step explanation:
The grade of pedal edema in which an indentation pits up 8 mm and lasts more than 2 minutes is classified as Grade 3 edema. This type of edema indicates a more severe form of fluid accumulation in the tissues. In clinical practice, edema grading helps physicians assess the extent of swelling and provide appropriate treatment. Grade 3 edema usually requires immediate medical attention as it can be a sign of significant underlying pathology.