Scientific studies on air breaks

[steinbil]

My tox in 2010 happened at 6m

What kind? Did you convulse? Have symptoms underwater? Pulmonary issues after the dive?

And what was the exposure?

 

[Vicko]

I have seen a number of cases where rebreather divers have trouble breathing after completing their deco. The symptoms are very similar to o2 lung toxicity. These are not "extream" exposures, dives to 70-110m, almost always bellow 5 hour run times.
Not exactly the scientific method.

 

[Matan]

Anecdotally, I am aware of guys who have had pulmonary symptoms on extreme exposures.

Same here - except not extreme exposures.

So in answer to OP:

1. If one asks himself "should I risk my lungs over + 10 minutes of deco?" the answer is obvious to me.
2. I'm not aware of any agency not recommending air breaks beyond a certain time on high PPO2.

Matan.

 

[PR_SMITH]

Like many things in technical diving, air breaks seem to not have a consensus among the scientific and agency communities (eg deep stops, optimal GF, etc).

Looking for any scientific studies that helps shed light on the following:
1) are air breaks effective in reducing oxygen toxicity/seizure hits?
2) if yes, what the recommended air break method is (12/6, 20/5, etc)

I know Simon Mitchel is on here; if someone knows how to @ his user that would be great

Air Breaks During Hyperbaric Treatment by Darren Mazza, EMT, CHT - Rx Pad - Wound Care Education Partners

When treating patients with hyperbaric therapy in the monoplace chamber using 100% oxygen, the supervising hyperbaric physician may order air breaks to be provided to the patient at certain intervals during the treatment.

www.woundeducationpartners.com

Although this is about o2 in hyperbaric chambers, it does deal with the reasons for air breaks from 100% o2

For those who want more math:

Effect of an air break on the occurrence of seizures in hyperbaric oxygen therapy may be predicted by the power equation for hyperoxia at rest

www.ncbi.nlm.nih.gov

 

[ScubaSamScubaStevesFather]

What kind? Did you convulse? Have symptoms underwater? Pulmonary issues after the dive?

And what was the exposure?

@nickbutcher I’m also very interested to know the details

 

[nickbutcher]

What kind? Did you convulse? Have symptoms underwater? Pulmonary issues after the dive?

And what was the exposure?

This is the report I wrote shortly after. I do many things differently now (13 years later):

 

[KevinNM]

I don't know of any such studies, and I seriously doubt there are any. How would you conduct them?

In all the reading I have done in related issues over the years, I have never heard of oxygen toxicity taking place in shallow water during a decompression stop. One could say that proves that air breaks help, or one could say that there might never have been a need for them in the first place.

Every case of oxygen toxicity that I know of has occurred at greater depths with people using incorrect mixes for the depth. It is usually a labeling error.

The use of air breaks is because of a concern about pulmonary oxygen toxicity. I don't know of any cases of pulmonary oxygen toxicity at any depth. I am not saying it hasn't happened; I am just saying I have never heard of one.

Per one of doctors here, there was a fatal CNS case on OC at 1.3 with a female cave diver some years ago.

 

[Manatee Diver]

Per one of doctors here, there was a fatal CNS case on OC at 1.3 with a female cave diver some years ago.

2007, they were using 24/25 with a max depth of 150ft.

You can pull the accident report up on the IUCRR website.

 

[boulderjohn]

In all the reading I have done in related issues over the years, I have never heard of oxygen toxicity taking place in shallow water during a decompression stop.

Per one of doctors here, there was a fatal CNS case on OC at 1.3 with a female cave diver some years ago.

2007, they were using 24/25 with a max depth of 150ft.

You can pull the accident report up on the IUCRR website.

I'm confused. Is this an example of "oxygen toxicity taking place in shallow water during a decompression stop"?

 

[KevinNM]

I'm confused. Is this an example of "oxygen toxicity taking place in shallow water during a decompression stop"?

You said it only happens at very high O2 pp. True, if you consider 1.3 to be very high. But typically people mean above 1.6 when they talk about very high. And then there was the poster who mentioned his little issue at 20ft.