Question Long term effects of O2 pulmonary toxicity

[Gelirfella]

There were millions of Americans alone that died of it during COVID (Alpha wave) when we couldn't dial the FiO2 on the vents down. It takes 3-4 days at 100% at 1 ATA to kill a person... unfortunately... To quote a famous scientist: "Science doesn't care what you believe..."

This is an overstatement. Also a physician. Not a pulmonologist but have a good bit of icu time under my belt and 100% FiO2 for 4 days at 1ATA will not definitively kill a person. Or damage their lungs so badly that they can’t recover. I don’t know what the long term effects will look like but absolutely had multiple patients after months on VV ECMO who were on 100%FiO2 for far longer than 4 days who walked out of the hospital during peak COVID. Definitely the exception, not the rule. But have seen many patients recover from ARDS after 100% FiO2 for a week or more and some who were eventually weaned off oxygen. Again, not certain of long term effects.

Pulmonary oxygen toxicity is real. But the studies on it are largely around ventilated patients who are sick. Hyperbaric medicine is a different beast and you don’t dive patients in a chamber who are well outside of research where people have definitely tolerated hyperbaric O2 to significant levels without injury. Healthy individuals inhaling higher than physiologic oxygen concentrations for short intervals periodically over decades is just not something that has been rigorously studied as far as I can tell. And conducting that study would be fraught with problems. Much of the pathophysiology of diving seems to exist in sort of a no man’s land where theory abounds but hard data is lacking. And extrapolating from sick and ventilated patients is a poor substitute. The sample size for diving is just absurdly small and there’s not much reason to study it practically. I’ve been consuming literature on it to try and get a sense of what is actually known and there’s not much.

 

[Capt Jim Wyatt]

Yea I am calling BS on my own post. I don't know how I got that info wrong on covid and apologize to the gallery. I am trying to find out but am thinking I should just probably STFU.

 

[Superlyte27]

Yea I am calling BS on my own post. I don't know how I got that info wrong on covid and apologize to the gallery. I am trying to find out but am thinking I should just probably STFU.

Lol, was alcohol involved? If so, pretty sure you get a pass

 

[Capt Jim Wyatt]

Lol, was alcohol involved?

Not this time...

 

[boulderjohn]

Total US Covid deaths (TD) = 1,174,578 According to @boulderjohn (I suspect more than that

I'm sure it is more than that, but we only have official numbers to work from.

Reporting guidelines varied from state to state, and politics played a huge part in it. For example (going from hazy memory), in Alabama a covid virus had to raise its little arms up under a microscope and say, "You got me! I confess!" OK, that's an exaggeration, but not by a lot. The issue was comorbidities. If the person had some other illness at the same time, what do you say caused the death? If a person with covid fell off the roof and broke a neck, that should be obvious, but what happens if the person with covid dies of pneumonia? In Russia, covid deaths were shockingly low, but they had an incredible increase in the number of people dying of pneumonia. IIRC, something similar took place in Alabama--if both lungs were shot, you could attribute it to the covid; if only one lung was shot, it was pneumonia (or something like that).

 

[Duke Dive Medicine]

“Millions” of Americans died because they couldn’t dial the FiO2 on the vents down? Something seems wrong with this statement.

The "millions" part is hyperbole but the rest of it is absolutely correct. Some patients' lungs were so badly damaged by COVID that it took high ventilator pressures and O2 percentages to adequately oxygenate them. That high O2 percentage over multiple days (and even weeks) led to pulmonary oxygen toxicity which exacerbated the lung damage and made it even harder to oxygenate them. It was a vicious cycle that was horrible to witness.

 

[tridacna]

The "millions" part is hyperbole

That's all I'm arguing about. Nothing else.

 

[Duke Dive Medicine]

After all the recent discussion of CNS limits, and some confusion regarding limits for pulmonary toxicity and OTUs, I have a question about the long term effects of elevated O2 exposure on the lungs.

Is the lung damage from O2 pulmonary toxicity fully reversible? Does it depend on the severity of the damage? What is the chance of permanent damage from high O2 exposure? Does this damage stack up over time, even after recovery?

Any data on the lung health and function of older divers with a long career in diving behind them? Maybe something from the commercial diving industry?

@Imla @Wookie @Superlyte27 @PfcAJ @Duke Dive Medicine

Not all cases of pulmonary O2 toxicity cause lung damage. If someone has mild symptoms like a cough and mild bronchial irritation, there's typically a transient reduction in pulmonary function that resolves over time. The longer the individual is exposed, the more likely the damage is to be permanent. For a diver to suffer permanent lung damage from pulmonary O2 toxicity, that diver would have to be exposed to extremely high partial pressures of O2 for a long period of time, which doesn't typically occur during diving.

Best regards,
DDM

 

[JMBL]

(...) For a diver to suffer permanent lung damage from pulmonary O2 toxicity, that diver would have to be exposed to extremely high partial pressures of O2 for a long period of time, which doesn't typically occur during diving.

I remember reading that in my TDI Nitrox course. It was around 2 000. I don't want to open a can of worm or stir a hornets nest, but if O2 toxicity was a high risk for hobby divers, Nitrox as a bottom gaz or for deco wouldn't be so popular I guess.

When diving a rebreather, the equation changes a bit, I was reminded of that during my Triton training.

Of course, the story is altogether different for commercial divers. I think, but cannot check, cause my books are not a hand, that's there a chapter or at least a detailed paragraph on the subject in both the US Navy and NOAA diving manuals.