Are there any issues with supping the unmixed O2 and air during separate times in the inhalation phase; does the lung care? Or could there even be an advantage to sending air or full 100% O2 first, then following up by the other?
This isn't ideal for two reasons.
1) You won't know what fraction of oxygen is reaching the patient. Of course a lot of mixing will occur in the tubes just from turbulence, but there might be significant variation if the oxygen and air don't fully mix. It could be like a train with separate cars on a track, one breath is high FiO2, the next breath is low. Averaged over time it might equate to the actual FiO2, but thats not what the lungs are seeing at each breath.?This could give a false impression of how much oxygen the patient is actually requiring which could complicate patient assessment. Probably not a huge issue, but hard to say for sure.
2) High oxygen concentrations can be damaging to cells. We sometimes need to use high concentrations, but we avoid it when we can. If the gases didn't mix and the patient was alternating between high concentrations breath and low concentration breaths then the high concentration breaths will put more oxidative stress on the cells. I don't know what the real world result of this would be, but the cells are already pushed to the limit.
Steve S
