Is oxygen a medicine?

[The Iceni]

On a thread concerning potential incidents of DCI it became apparent that, in the US at least, oxygen is considered a medicine and may only be "administered" on the surface by suitably qualified individuals for treatment of medical emergencies.

TwoBitTxn once bubbled...
. . . Medical O2 in the states is considered a drug. An EMT can administer O2 in an emergency.

In the field or recreational diving this leads to the very odd situation where technical divers can use it for accelerated decompression underwater and on the surface, but it may not be given (to non-technical divers) to prevent DCI in those marginal cases where a diver has suffered a minor violation of his decompression obligations until he develops symptoms.

If the diver believes he may benefit from 100% oxygen and does not have his own, this has the inevitable consequence that someone (the skipper?) must declare a medical incident, with all that entails, because oxygen can only be used on the surface for treatment of a "medical emergency".

I believe this must be counterproductive because it prevents the use of oxygen in circumstances where it is of proven benefit and pressures the diver to deny any problems until it is obvious.

Is this sensible?

Before voting, please read on.

Dr Deco once bubbled
Oxygen

I have been following the development of this thread for the past day, and, from the viewpoint of physiology, would like to offer these comments.

1. 
   [*]There is not any “bends/no bends” limit, but rather it is a progression of bubble growth associated with the nitrogen “dose.”
   [*]If the nitrogen dose were sufficient, all decompressions would develop into a case of DCS (assuming that micronuclei were present).
   [*]Breathing oxygen will speed the off gassing of dissolved nitrogen and than in bubbles also.
   [*]This unloading occurs whether or not you have a few bubbles or many bubbles.
   [*]You can assist nitrogen elimination by breathing oxygen.
   [*]Some tech divers breath oxygen during the shallow stops, some breathe it on the surface (“the hidden stop”), and some breathe it on the boat. They do this whether or not they have DCS.
   [*]Oxygen will not “mask” symptoms; it is not an anesthetic or any other type of anodyne (pain reliever).
   [*]Symptoms, even neurological, can remit spontaneously; in the old days, this type of regression was the only recourse a diver had.
   [*]Symptoms can remit with or without oxygen, but I would head for a chamber in any case.
   [/list=1]

1. I find it very odd indeed that oxygen is not a medicine when used for decompression underwater but it becomes a medicine when it is also used prophylactically to prevent potential DCI on the surface
   
   Perhaps this causes unecessary problems?
   
   I would suggest that it would make a great deal of sense to lower the threshold for the use of surface oxygen, allowing asymptomatic divers who believe they may be at minimally increased risk to use it "just in case", rather than reserve its use for "incidents" with an inevitable chain of events that follow.
   
   As Genesis has suggested, oxygen may not have been given, when it should have been, because of the strong peer pressure one feels not wanting to be a nuisance and the cause of an incident. This leads to the dangerous phenomenon of "denial".
   
   I often use 100% oxygen from my stage bottle, solely as a precaution, when climbing the ladder and for a minute or two following certain dives if only because I have access to it, having already used it for my shallower stops.
   
   Does this constitute an "incident" each and every time and why does it need to become an incident if another asymptomatic diver (who does not have access to his own deco gas) wishes to avail himself of it, or indeed that special cylinder of "medicine" in the sealed box?
   

 

[Dr Deco]

Dear Dr Thomas:

Oxygen as a Drug

I do not actually know the status of oxygen as a drug in the United States. I do know that many oxygen cylinders do state ”For use only by a physician or on the order of a physician.” This depends upon where the gas is purchased. If it is from a welding supply house, I do not believe one sees this restriction. If it is purchased from a medical supply firm, the cylinder is so labeled.

This is more likely than not an indication of a restriction on a presumed, medical use by an individual. Many things would carry the warning depending on circumstances. Physiological saline contains only table salt and water but is restricted in its sale. Many compounds are available from a chemical supply house but cannot be purchased from a pharmacy without a prescription. Again, I guess this is a presumed medical use.

Divers Oxygen

To my knowledge, oxygen can be administered on a dive boat by divers. Equipment for this is sold by DAN. I am not certain of the specifics. We can assume that the usual contraindications to oxygen (e.g., emphysema with carbon dioxide intoxication) will not be present in a recreational diver, and thus, the big “No No” is avoided.

I would hope that medical jargon would not deter a diver in the use of oxygen in decompression or off gassing situation. Certainly, this is true of any case of DCS .

Other Thoughts

I would welcome thoughts by our readers on this topic of the medico-legal aspects of oxygen use.

Dr Deco :doctor:

 

[The Iceni]

Dr Powell,

Thanks for you input.

I was interested to learn that you do not know the legal status of medical oxygen in the US. Twobit appears to confirm that it is Prescription-Only (POM), which is one thing I seem to remember being taught as a medical student here;- the difference is the reason I remember it.

Here it is a criminal offence, under the Medicines Act 1968, for any person, other than a doctor, to sell, supply or administer any POM to any individual unless instructed, or authorised to do so, by a "registered medical practitioner".

There are exceptions to this statute. These exemptions decriminalise the use of such medication in a life-threatening emergency, by other duly authorised individuals who have undertaken "appropriate training", such as paramedics and EMTs. Even if oxygen were a POM here this would allow those divers and charter skippers, who have taken the oxygen administration course, to use it on others - but only in an established medical emergency.

If this is the case I am not surprised there is reluctance on the part of charter boat skippers to allow its use without making a Mayday call.

The label you quote, found on your medical oxygen cylinders, is almost identical to the one on all POMs in Britain, which seems to confirm the impression I have that it is indeed a POM. Perhaps the US MDs on board could enlighten us?

If this is the case, in the US or elsewhere, the prophylactic use of oxygen by dive skippers, when there is no confirmed "medical emergency", would indeed constitute a criminal offence.

Interesting unintended ramifications of sensible legislation?

 

[Cherry]

I can't answer as a Doctor but as a trained First aid attendant I can tell you what the "legal" position of Oxygen administration is in Canada. Oxygen is considered a "requirement of life" and therefore its administration is covered under Good Samaritan legislation which saves harmless an individual giving oxygen ( or any aid of an emergency nature) to a person in distress. Really the only issue around oxygen is that the individual should be trained in the use of the equipment. Kind of a simple task that is dealt with by clear instructions printed on the equipment itself. Mind you I know how you folks in the US like to complicate things eh

 

[AquaTec]

just a quick note

O2 is considered a drug, or therapy, or a first aid treatment.

yes it is used in tech diving, by trained indaviduals


as for rec divers, only trained persons should use it.

for instance they need to know about CUPD
O2 on a boat for non tech divers should be concidered treatment or first aid...i understand it can be considered prevention, but if you didn't dive you wouldn't need it.. so it is more treatment

 

[TwoBitTxn]

Cherry,

A lay person administering O2 in the field could be in trouble for acting beyond the scope of training. The good samaritan law may or may not cover that person.

I did state medical oxygen is classified as a drug.

As an EMT I was taught the conditions to use O2, when not to use O2, and how to use O2. We were taught that O2 is a drug.

Normally there is a divemaster on a chartered dive boat and a good dive master keeps CPR, First aid, and O2 provider certifications current. So if there is a medical emergency on the boat, there is a trained person on board.

If this is the case, in the US or elsewhere, the prophylactic use of oxygen by dive skippers, when there is no confirmed "medical emergency", would indeed constitute a criminal offence.

In my opinion the simple way around this is self administration. If it is a prophylactic use the person using it should be able to aquire the bottle, set it up, and utilize it with little assistance.

TwoBit

 

[Genesis]

is that I will not "administer" anything to anyone but myself, but I will (and do) tell everyone who gets on my (private) boat where the O2 is.

I keep it set up for immediate use, with the regulator on the bottle, and the valve wrench chained to the kit! Its darn hard to get it wrong - stick the demand valve in the oronasal mask, turn on the bottle, breathe. Heck, if you want, stick the valve in your mouth like a reg and SUCK! It WILL work if you do that, even if it is a bit uncomfortable!

Everyone receives the knowledge in their basic OW cert that 100% O2 is the gold standard for "first aid" in the event of a suspected DCS or AGE incident.

Exception is made for an unconscious person or worse (in respiratory or circulatory arrest!) Then a quick poll will be made of the people on board, and the two best-qualified and willing among those on board will begin and perform CPR or otherwise act as is rational under the circumstances. You can't kill the already-clinically-dead, but you might be able to save them, and I WILL try.

My position on O2 is that it is a gas that is known to have very few contraindications when breathed at 100% for the amount of time that I have gas supply (roughly 2 man-hours) on board. If you have any of the conditions that would contraindicate its use it would be essentially impossible for you to be diving in the first place.

My further position goes something like this:

1. We now KNOW that all dives are decompression dives.

2. The last part of your decompression, whether you are diving in a so-called "NDL" profile or not, is done on the surface, and extends until you are completely desaturated from Nitrogen back to a PN2 of 0.79.

3. To the extent that your dive profile has been exceeded unintentionally, whether you were on a "no decompression" profile or not, you are at a statistically-greater risk of a DCS hit.

4. Breathing 100% O2 on the surface for a period of time will, as a scientific fact, accelerate the perfusion of N2 out of your body.

5. If you have a dangerous overpressure of N2 in your body's tissues, then breathing 100% O2 will serve to reduce that overpressure. That reduction may PREVENT a hit that you would otherwise take, and even if it does not, it is very likely to either delay the onset of symptoms, reduce the severity of them, or both.

Therefore, it is my position that 100% O2 should be available to any diver who requests it post-dive on their own initiative as both a routine matter and without triggering the "you started a course of treatment" nonsense. That is, we should encourage divers who believe they may benefit from breathing 100% O2 on the surface to do so.

To the extent that physicians who dive understand and agree with this position, I call upon them to make efforts to change the current legal status of O2 such that this can be implemented as a routine matter.

Why?

Because the biggest risk to a diver who has blown a profile is denial. Denial that they are at risk of a DCS hit. Denial that what they're feeling IS a DCS hit. Denial and delay are bad, and discouraging the use of O2 in such a case places the diver at greater risk, particularly if they are discourage from asking for and using the O2 because they know that asking for the O2 bottle will trigger an inevitable and immediate categorization of them as a "casualty" by the dive operator.

Now a diver who has, by outside observation, or self-reports symptoms and signs that are consisted with DCS must be treated as if they HAVE DCS until proven otherwise. In such a case medical response is appropriate - along with the O2.

But for the NON-SYMPTOMATIC diver who requests O2 as a means of warding off a potential problem, I say we should support and applaud such a decision, not punish it.

 

[AquaTec]

Genisis
One thing i will add.

if a diver starts on O2, then he must track his OTU's just in case he does do that chamber ride

 

[The Iceni]

Pos-tech once bubbled. . . I did many repeditave dives over 4 days on the fith dive of the fourth day there was an insidant involving a paniked diver draging me to the surface. That day I had already done 3 dives all to over 120ft (a normal trip for me) . . . was at about 60 feet with over 20 minutes of deco when a diver grabed and decided to "help" me surface in about 30 seconds . . . I did not take O2 because I showed no signs of dcs. am I just very lucky?????????

Lucky? IMO Most certainly.

To my mind this illustrates the point I am making so well. It was hardly a minor violation - rapid ascent after multiple dives over multiple days with 20 minutes of missed deco where, with the benefit of that powerful medical instrument the retrospectoscope, Pos-tech was a prime candidate for DCI.

It would seem to me that denial played a major part in this incident and the failure of the dive marshall or skipper to put Pos-tech on oxygen is worrying. Had I been present I think I would have treated this incident very differently but minor violations are very, very common as is denial and to my mind the this is simply because of the legal status of oxygen administration as "medical treatment".

As for OTUs Aquatec, may i suggest you take a look at the figures. This is not a problem at all in recreational diving. 1 unit per minute during the evacuation is not going to make any difference, whatsoever, to the casualty's risks of pulmonary toxicity or to the hyperbaric physician's decision whether to recompress or not. DCI is a major. life threatening condition, pulmonary oxtox is a relatively minor consideration.

Surely prevention is better than any attempted cure?:doctor:

 

[david.tolan]

Where do you draw the line between -

I'd like to take O2 just in case,
and
I'd like to take O2, call an ambulance just in case ?

Also there is a flip side, when a person looks for O2, if no medical emergency is declared, then (s)he subsequently goes on to develop DCS, someone may well stand up and point fingers at the skipper and say why didn't you call it in.

Just a thought.

Dave