Question about Hyperbaric Oxygen Therapy

[dberry]

Just for the heck of it I checked out the website of the hyperbaric facility closest to my home, which turns out to be at Penn (Univ. of Penn, in Philadelphia). In reading the blurb for their fancy multi-patient chamber, this statement caught me by surprise:

By breathing 100 percent oxygen at elevated pressure (2.0 to 3.0 atmospheres), 20 times more oxygen travels through the body's bloodstream to injured organs and tissue, causing accelerated healing and other beneficial effects.

So, do I need to return my nitrox cert card because I clearly don't understand O2 toxicity? Or maybe they consider CNS toxicity and convulsions a "beneficial effect"? It seems to me that 3.0 atmospheres of 100% O2 constitutes a pO2 of 3.0, and 3.0 > 1.4 (>1.6, too), but feel free to double check my math.

This site is aimed at giving an overview of their facilities and treatments, and I suspect it's a screw-up that conflates treatment with hyperbaric AIR at 2-3 atm with some other treatment they offer that uses 100% O2, possibly at (slightly) elevated pressures (say, up to 1.4 atm ?) OTOH, one could fill encyclopedias with all the things I don't know or understand... Any hyperbaric docs out there able to clear up my confusion?

Here's the link to the page:
Services | Hyperbaric Medicine | Clinical Services | Department of Emergency Medicine | Penn Medicine

-Don

 

[tursiops]

No problem with what they are doing or saying. There are attendants and no water to drown in should there be a seizure.

Sent from my SAMSUNG-SM-G900A using Tapatalk

 

[TONY CHANEY]

No worries! I dove several patients while in school with Dive table #6 mainly for wound care. https://www.virginiamason.org/TreatmentTablesforHyperbaricOxygenTherapy

 

[pisoiu]

I am not a specialist in this area, but I am also interested in this subject. Few months ago I dove down to 50 meters in a hyperbaric chamber (air only) and prior to my simulated dive, I observed a treatment session for some patients. From what information I have, I can tell this (hope I'm not mistaking)
-treatments in hyperbaric chamber may go way over ppo2's used by divers, but somehow effects of high ppo2s in air are different than in water. I just heard that, not sure about it.
-the chamber, at least that type for multiple patients is filled always with air
-any other gas mixture, including o2, is administred using a facial mask and the exhaled air is also extracted using the same mask and vented outside the chamber environment.
-administration of other gases, including pure o2, may not be done during the entire session, which can take hours, rather it is done in sessions of x minutes using facial mask, then pause for y minutes, breathing air from chamber, then repeat.
-pressurisation and depressurisation of patients is done using speeds much lower than ascending/descending speeds used by divers
-treatments are usually done at a equivalent pressure of approx 20 meters

 

[huwporter]

There is a non-zero chance of toxing during a chamber treatment - however:

1. In a hospital chamber, you'll have an attendant on hand in case you do tox;

2. the consequences of toxing in a chamber are much less severe - specifically there is no risk of drowning (the toxing itself isn't going to kill you even underwater, but becoming unconscious, paralysed and so drowning will...);

3. you'll do air breaks interspersed in between the time on oxygen (the oxygen is administered through a face mask, the actual chamber itself will be filled with air) to reduce the probability, and;

4. in general the probability of toxing in a chamber at the same PO2 is lower than in water - probably at least partially because you are much less likely to retain CO2 when lying on a bed as compared to swimming around.

Cheers,
Huw

 

[DocVikingo]

Hi Don,

Yes, forms of O2 toxicity can and do occur during recompression, but the incidences are quite small, and, as others have mentioned, typically easily managed.

Incidence of oxygen toxicity during the treatment of dysbarism.
Author:	Smerz, RW
Abstract:	Oxygen (O2) toxicity may result from exposure to partial pressures of O2 above 0.6ATA. Potential toxic exposure for divers occurs during the treatment of dysbarism. In the recompression chamber, PO2 may range from 0.9ATA to 3.3ATA depending upon the treatment table employed. This retrospective study examines the nature and incidence of O2 toxicity in 998 patients who underwent recompression treatment at our facility from 1983 through 2001. Only patients evaluated for diving related injury were considered for this study. Of 1189 charts reviewed, 998 patients received recompression and were entered into this study. The total number of treatment exposures was determined as was the total number of O2 toxicity events characterized as either pulmonary or CNS, and patients were divided into male/female analysis. Overall incidence as well as the incidence for both toxicity types was determined, and their occurrence in both male and female patients was ascertained. 2166 recompressions were undertaken, 449 female and 1717 male. The peak PO2 for these treatments ranged from 2.6ATA to 2.9ATA. 155 O2 toxicity events occurred in 152 patients, 49 females and 103 males. Three patients, 2 females and 1 male, had mixed events. Incidence of an O2 toxic event = 7.0 per 100 recompressions. Incidence of pulmonary toxicity overall = 5.0 per 100 recompressions, while CNS events = 2.0 per 100 recompressions with overall seizure rate = 0.6 per 100 recompressions. In females, pulmonary toxicity rate = 6.9 per 100 recompressions, CNS toxicity rate = 4.4 per 100 recompressions with seizures occurring at 1.3 per 100 recompressions. In males, pulmonary toxicity rate = 4.6 per 100 recompressions, CNS toxicity rate = 1.4 per 100 recompressions, and seizures at 0.4 per 100 recompressions.
Description:	Undersea & Hyperbaric Medicine : Journal of the Undersea and Hyperbaric Medical Society, Inc.
URI:	Incidence of oxygen toxicity during the treatment of dysbarism.
Date:	2004

Regards,

DocVikingo

 

[Akimbo]

… So, do I need to return my nitrox cert card because I clearly don't understand O2 toxicity? …

This was written with divers just like you in mind.

Oxygen Toxicity Limits & Symptoms

Here is the intro:

Oxygen toxicity limits can be very confusing, especially for PPO2 levels above 1.6 ATA used in chamber-based hyperbaric treatment (recompression) and decompression tables. For example, here is a chart of one of the most common DCS treatment tables. Note that that the PPO2 of pure oxygen at 60'/18.3M is 2.82 ATA — or more than twice the normal limits recreational divers observe...