Possible Developments in the Treatment of Critical COVID-19 #2
In most cases of respiratory failure (pneumonia, heart failure, ARDS) the small air cells, the alveoli, fill up with fluid or collapse. So we maintain a higher constant pressure (PEEP: Positive End Expiratory Pressure) in the airways to hold them open, and it works well. Um, usually. But COVID seems to be different. More oxygen (normal room air = 21% O2) by which I mean a higher fraction of oxygen delivery up to 100% definitely helps. But the positive pressure ladder which worked well in ARDS seems maybe not to work in covid, and maybe even harms the lungs. We've always known that a high level of positive pressure is a double edged sword, but in covid maybe the harms clearly exceed the benefits, which would be truly new.
This is not to say we should not ever intubate. But it does mean that a) we should avoid intubation as much as possible by increasing the inhaled oxygen and b) if we do have to intubate, then the high positive pressures we have traditionally used maybe are to be avoided, even if it means allowing the blood to have less oxygen in it that we would traditionally accept.
So why would we intubate if it's harmful? So traditionally we would intubate for "low oxygen level" - and this (maybe) is out the window. But if a patient is too exhausted to continue to draw air in, or too out of it to protect their airway, these are still obligatory reasons to intubate. We can't get around those. But it's seeming clear that anything we can do to increase the number of ventilator-free days is a good thing, and this is a new understanding.
And having seen the videos, I also have to say the "crazy" hypothesis remains valid. But Dr Kyle-Sidell may be crazy but I don't think he's wrong. To be clear, he is also not a "lone voice" in the wilderness. He's reflecting an evolving consensus among docs who have managed a lot of covid.