Dead zones may be corrected by supplying 100% inspired oxygen; when a capillary is blocked, the blood inside of it does not flow and upstream blood distributes between other capillaries that are exchanging gases effectively.
Dead zones may be rectified by providing supplemental oxygen; when a capillary is occluded, the blood within it ceases to circulate, prompting the redistribution of upstream blood among other capillaries that are efficiently exchanging gases.