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 can be mitigated by supplying 100% oxygen; when a capillary becomes blocked, the blood inside it fails to flow, triggering the redistribution of upstream blood among other capillaries that are effectively exchanging gases.