I'd like to see some comparisons of going on oxygen, using scuba gear, vetalator, hyperbaric chamber. Never heard of someone on the surface having a scuba regulator kill them. The newer/more expensive ones can provide positive air pressure to make it easier to breathe. A vent tube and the end are overpriced plastic, and hooked up to an expensive machine. SCUBA regulators are much more expensive in design and materials than the plastic, but not nearly as expensive as the vent machine. Regulators are priced reasonably for what they are, but I'm sure the medical industry can make them more expensive. Not many hyperbaric chambers exist, and are expensive to use. The airlock could get to be time consuming for the nurses.