After dive oxygen: shouldn’t the diver decide?

[KenGordon]

Freewillie, you put that as though there is no downside to chamber treatment. High partial pressure oxygen for several hours, plus potential subsequent treatments may lead to pulmonary oxygen toxicity, especially if lots of high ppo2 diving went on beforehand. That is no fun at all, but perhaps less scary than untreated neurological bend.

It would be interesting to know how many people that end up in a chamber decided to go after several days, rather directly as an emergency.

 

[Akimbo]

Freewillie, you put that as though there is no downside to chamber treatment. High partial pressure oxygen for several hours, plus potential subsequent treatments may lead to pulmonary oxygen toxicity, especially if lots of high ppo2 diving went on beforehand. That is no fun at all, but perhaps less scary than untreated neurological bend...

Pulmonary Oxygen Toxicity is so minor in an otherwise healthy individual with DCS it is insignificant. Recovery is usually within a week and is closer to uncomfortable than miserable. The big risk isn’t over-treating DCS; it is missing other untreated medical conditions that could harm the patient far more than an unnecessary chamber ride.

DCS is a much safer bet on a boatload of tech or commercial divers that are all under 40. The incredibly difficult part is the boatload of recreational divers between 18 and 80 that are within their No-D limits. Keep in mind that DCS diagnosis is a bet, not an observable condition like a gunshot wound.

 

[freewillie]

Freewillie, you put that as though there is no downside to chamber treatment. High partial pressure oxygen for several hours, plus potential subsequent treatments may lead to pulmonary oxygen toxicity, especially if lots of high ppo2 diving went on beforehand. That is no fun at all, but perhaps less scary than untreated neurological bend.

It would be interesting to know how many people that end up in a chamber decided to go after several days, rather directly as an emergency.

The only downside for treatment is the time spent in the chamber. I'm not so sure about divers with DCI being treated but I know for a fact my wound care patients can't have anything in the chamber with them. The danger of a spark igniting the oxygen is very real so no paper books or electronics. You are in the chamber with only a cloth gown. The do pipe in music or sometimes have a tv outside the chamber but that's all. As for pulmonary toxocity that is not an issue for the time in the chambers. It's only an issue for ventilator patients on 100% O2. At least medically. Don't ask me about tech divers mixing their gases. I'm strictly recreational diver only.

 

[drrich2]

There are other side-effects of chamber treatment; confinement in the chamber, unplanned 'vacation' extensions, high expense, early termination of diving, possibly having to book & pay for airfare home… If you really need it, you really need it. Otherwise...

Richard.

 

[Akimbo]

… The danger of a spark igniting the oxygen is very real so no paper books or electronics...

That is particularly true for monoplace (one-person) chambers, sometimes called torpedoes. The reason is the entire chamber atmosphere is usually nearly pure O2, which is a much greater fire risk than during the Apollo fire, which was at one atmosphere.

Here is an image of a monoplace from Alert Diver Magazine, Q1 Winter 2015


A multiplace chamber is preferred for treating DCS because treatments can be deeper than many monoplace chambers are rated for, Oxygen is administered by oral-nasal mask, and an attendant can be inside. That makes it possible to protect the patient from hurting themselves during an Oxygen convulsion, perform CPR if necessary, hang IV bags, take vitals for the hyperbaric doc outside, administer Oxygen if the patient is unconscious, and Oxygen exposures are usually much longer than most HOTs patients and separated by “air breaks”. For example:

• 60' for Table 5 & 6
• 165' for Table 4, 6A, & 7
• 225' for Table 8

Again, look at the chart of Table 5.


Air breaks are possible because the chamber atmosphere is air and the diver breathes from a BIBS mask (Built-In Breathing System) when on O2. Of course Oxygen levels, and therefore the fire hazard, on air alone is much higher than on the surface. Most (maybe all???) multiplace hospital chambers today use a BIBS mask with a demand regulator for supply AND exhaust. The exhaust is vented outside so the chamber atmosphere isn’t contaminated by even higher oxygen levels.

Many multiplace chamber operators allow divers to bring a book in with them because the fire risk is lower than a monoplane chamber filled with pure O2. You will often see a sign like this near the entrance to a chamber:

 

[KenGordon]

The only downside for treatment is the time spent in the chamber. I'm not so sure about divers with DCI being treated but I know for a fact my wound care patients can't have anything in the chamber with them. The danger of a spark igniting the oxygen is very real so no paper books or electronics. You are in the chamber with only a cloth gown. The do pipe in music or sometimes have a tv outside the chamber but that's all. As for pulmonary toxocity that is not an issue for the time in the chambers. It's only an issue for ventilator patients on 100% O2. At least medically. Don't ask me about tech divers mixing their gases. I'm strictly recreational diver only.

So it never happens that chambered divers end up with a bad cough and difficulty breathing due all that time on high pressure O2? Or maybe they do:

http://archive.rubicon-foundation.org/xmlui/bitstream/handle/123456789/4010/15485081.pdf?sequence=1

The rules against flammable stuff are the same. Indeed there is every chance a diver will end up in the pot with HBOT patients after the first long decompression.

Doing a week of 30m dives on 32% is hardly technical gas mixing.

 

[beanojones]

That is particularly true for monoplace (one-person) chambers, sometimes called torpedoes. The reason is the entire chamber atmosphere is usually nearly pure O2, which is a much greater fire risk than during the Apollo fire, which was at one atmosphere.

Here is an image of a monoplace from Alert Diver Magazine, Q1 Winter 2015
View attachment 206083

A multiplace chamber is preferred for treating DCS because treatments can be deeper than many monoplace chambers are rated for, Oxygen is administered by oral-nasal mask, and an attendant can be inside. That makes it possible to protect the patient from hurting themselves during an Oxygen convulsion, perform CPR if necessary, hang IV bags, take vitals for the hyperbaric doc outside, administer Oxygen if the patient is unconscious, and Oxygen exposures are usually much longer than most HOTs patients and separated by “air breaks”. For example:

• 60' for Table 5 & 6
• 165' for Table 4, 6A, & 7
• 225' for Table 8

Again, look at the chart of Table 5.
View attachment 206082

Air breaks are possible because the chamber atmosphere is air and the diver breathes from a BIBS mask (Built-In Breathing System) when on O2. Of course Oxygen levels, and therefore the fire hazard, on air alone is much higher than on the surface. Most (maybe all???) multiplace hospital chambers today use a BIBS mask with a demand regulator for supply AND exhaust. The exhaust is vented outside so the chamber atmosphere isn’t contaminated by even higher oxygen levels.

Many multiplace chamber operators allow divers to bring a book in with them because the fire risk is lower than a monoplane chamber filled with pure O2. You will often see a sign like this near the entrance to a chamber:
View attachment 206081

Ok it's got nothing to do with the topic, but what are the mixes for the 165 and 225? Are they also 2.8 ATA mixes?

Have you done 220' dives in a multiplace?

Did the University of Hawaii Hyperbaric Treatment Center follow what was already established by the commerical world when it was doing these 165'/2.8 ATA and 220'/2.8 ATA dives? I am wondering if the HTC and the commercial world were paying attention to each other, or whether the HTC was just all about killing pigs for luaus?

I know that we were doing vastly different treatments (on bent divers) than most recreational diver recompression chambers with always going deep, and extending some treatments for days. (But then again, the HTC was part of a research hospital treating people for free, because, well, research. Anyone could go directly to the center, pick up the phone and doctors, and inside and outside tenders would roll down to Kewalo Basin to treat the diver no payment needed.)

For KenGordon, the HTC was not at all worried about CNS Tox or Pulmonary Tox hits for bent divers because it was only worried about treating the DCS as quickly and aggressively as possible. We inside tenders were always with them so Tox hits got resolved quickly, and when people are paralyzed, Pulmonary Toxicity is far from an issue.

We got paralyzed divers who resolved at depth regained fuction, and lost function on ascent permanently. Pulmonary toxicity is not something a guy in a wheelchair is suffering from.

 

[Akimbo]

Ok it's got nothing to do with the topic, but what are the mixes for the 165 and 225? Are they also 2.8 ATA mixes?...

The standard US Navy treatment tables that go deeper than 60' just call for air. I am “guessing” that banking rich Nitrox treatment mixes was considered too much of a logistics problem for the Navy. Many diving jobs already have large quantities of Oxygen for OxyArc burning rigs anyway. The amount used for a treatment is tiny compared to burning.

As you know, the use of these deeper tables is surprisingly rare even when divers are bent from 300' plus dives — explosive and significantly omitted decompression being the exception. Compressing the bubbles to nearly a third provides relief the majority of the time and allows the use of pure O2. As far as I know, almost everyone uses USN treatment tables now.

Have you done 220' dives in a multiplace? ...

I’m not sure of the context to frame a reply. All US Navy First Class divers of my era made chamber dives to 285' on air and 300' in HeO2 for training. I have made quite a few chamber dives in the 250' range on air testing chambers and equipment. I have been well past 900' as a saturation diver. I have seen, but never been pressurized in monoplace chambers.

I personally have never been aware of DCS symptoms. I’m a little reluctant to say “never been bent” since some physiologists consider the formation of enough bubbles in the blood as bent even when asymptomatic. I have run treatments on others a few times that had to go to 165' for relief, but never 225'. The few sat treatments I have been involved in didn’t present symptoms until 100' or less.

Is the answer you were looking for buried anywhere in this answer?

… Did the University of Hawaii Hyperbaric Treatment Center follow what was already established by the commerical world when it was doing these 165'/2.8 ATA and 220'/2.8 ATA dives? ...

I’m not up to speed enough on HTC’s work to know. High PPO2 treatment mixes are a logical progression so I “imagine” it is a case of recurrent discovery rather than copying someone else’s lead. Commercial companies are pretty secretive with their proprietary tables.

I have seen commercial diving systems with mix-makers that blend treatment gases on the fly. They would run from about 1.5 to 3.3 ATA depending on the company. That was early in my career when deep bounce diving with a bell and chamber system was used. Thankfully, that has been replaced by full saturation and ROVs worldwide. Quite a few sat divers that are active today have never even heard of these deep bounce diving systems.

… I know that we were doing vastly different treatments (on bent divers) than most recreational diver recompression chambers with always going deep, and extending some treatments for days. (But then again, the HTC was part of a research hospital treating people for free, because, well, research. Anyone could go directly to the center, pick up the phone and doctors, and inside and outside tenders would roll down to Kewalo Basin to treat the diver no payment needed.) ...

Is that still the case at HTC? The days of any diver in need being treated in any available chamber seems to be long past. A frightening number of bent divers are turned away from chambers around the world today because DCS treatment would be inconvenient in their schedules.

I was an inside tender on one strange treatment that extended into an air sat.

…I was the inside-tender on a treatment in the 1970s on a competitor’s saturation diver found unconscious on the street in Stavanger Norway. Once alcohol was ruled out we started a table 5, which quickly slide into a 5a. Fortunately we were in a multi-chamber sat system. He regained consciousness at about 150'. He repeatedly lost consciousness on ascent so we slide into a saturation decompression table with high O2 treatments on BIBS (Built-In Breathing System) for him. We learned during decompression that he had not been under pressure for weeks before the event but we couldn’t just let him pass out again since the treatment was working. Besides, all three of us were also committed to a sat decompression schedule by then anyway.

He left the chamber symptom free after several days of “treatment”. I heard from the attending doc about a month later that he passed out again in Scotland. He had not been under pressure since we treated him and was diagnosed with some weird form (my words) of spinal meningitis. This is a case where he responded to treatment but had nothing to do with DCS...

I suppose that story helps to confuse the original question in this thread even farther.

 

[iamrushman]

i don't usually respond to threads such as this and prefer to monitor and lurk with this current topic of discussion. however, i was shocked to see the University of Hawaii Hyperbaric Treatment Center @ kewalo basin mentioned. i worked as an inside tender during the 1980s at this facility and am always looking for old work comrades that were associated with the late DR. Beckman.

 

[beanojones]

(Thanks for the stuff Akimbo!)

Here's what the HTC was doing at least at some points with bent divers. 2.8 ATA was the goal at all bottom depths. at 220, at 165, at 60. SO that meant 100%, 36%, and 44% on the mask in an air environment.

Our job as inside tenders was to monitor for CNS tox, pinwheel test, catherisation, ect.

Both the tender and the patient followed the same air break schedule. This high O2 mask to deep air, which seems to be somewhat unique to the old Kewalo Basin HTC, is where I don't get PADI's stance on O2 being narcotic.

There was, for me, an abrupt onset of narcosis when the high O2 mask came off into deep air.

That sudden onset narcosis, and the fact that 220 makes chipmunk voices anyway (and they made sure not to brief you on the chipmunk voice before the check out dive), was one of the most uncontrollably funny things to ever happen to all of us.

Nice overview of the HTC:

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