Which statement best describes the normal A-a gradient range?

Study for the Respiratory Therapy Test. Use flashcards and multiple choice questions, featuring hints and explanations. Prepare for your exam successfully!

The A-a gradient shows how effectively oxygen moves from the alveoli into the arteries. In healthy people, this gradient is small, but it increases with age because gas exchange becomes slightly less efficient and there’s more matching variability as you get older. Because of that, there isn’t a single fixed normal value; the expected gradient rises with age. That’s why describing it as increasing with age and not being a fixed value is the best answer. The other statements aren’t accurate because the gradient isn’t a universal fixed number, isn’t governed by metabolic rate in that simple way, and isn’t equal to the inspired FiO2.