YD Scuba Diving Forums banner
1 - 20 of 23 Posts

·
Registered
Joined
·
233 Posts
Discussion Starter · #1 ·
Hi
I'm in the middle of constructing some questions for the new Cave Diving Group exam paper, which encompasses some basic first aid. Traditionally, a question on the paper was relating to entonox and DCS. It implied that paramedics (and Technicians, as we too can give drugs - shock horror) would not know that entonox should not be used in cases of DCS or when someone had been diving in the last 24 hours.
It is in fact included in Technician and Paramedic training and drug procedures and guidelines (JRCALC) that Entonox is CONTRA-INDICATED in circumstances involving DCS or 24 hours after diving i.e we can't give it.
BUT there is rumour that it is not always the case that Entonox would aggravate the size of the bubbles or the pain. I have no substanciated evidence for this and Entonox has always been a big no-no with divers as far as I am aware.
Personally, I'm not sure that entonox would be my first choice of pain relief in severe cases of DCS anyway as it has to be self-administered. Does it ACTUALLY increase the bubble size ???
Would the benefits of the 50% oxygen outweigh a ?? risk ? In the absence of O2 (which I would sincerely hope would not be the case)
Do any dive medics/ physiologists out there have any info on any research into this ?
Many thanks for your time
Chris
 

·
bubbles mean your having a leak?
Joined
·
712 Posts
i was always told that its a big no-no because the body tissues dont contain any nitrous oxide, when you start breathing it - the body ongasses with it very quickly, thus increasing any bubbles in size very rapidly.

it makes sense to me - but there again i'm not a diving doc so i could be talking rubbish.
 

·
Nigel Hewitt
Joined
·
7,142 Posts
i was always told that its a big no-no because the body tissues dont contain any nitrous oxide, when you start breathing it - the body ongasses with it very quickly, thus increasing any bubbles in size very rapidly.
I don't see 'rapidly'. If a bubble is lodged it must be blocking the blood flow or it would be in inert gas poor tissue and be off gassing so it isn't actually going to get much NO2 but it's pushing in the wrong direction. I forget how NO2 works, I think it's a brain addler (intoxicant) rather than a tissue site-specific pain killer so I can see how it might be suggested for DCS pain where compromised blood flow makes delivery to a site is problematic.

It might seem mean but I would be very hesitant to administer any pain relief to a DCS patient. Let the hyperbaric specialist get the full picture and watch the response when they wind up the pressure.
 

·
GUE Tech and Cave Instructor
Joined
·
1,259 Posts
I don't see 'rapidly'. If a bubble is lodged it must be blocking the blood flow or it would be in inert gas poor tissue and be off gassing so it isn't actually going to get much NO2 but it's pushing in the wrong direction. I forget how NO2 works, I think it's a brain addler (intoxicant) rather than a tissue site-specific pain killer so I can see how it might be suggested for DCS pain where compromised blood flow makes delivery to a site is problematic.

It might seem mean but I would be very hesitant to administer any pain relief to a DCS patient. Let the hyperbaric specialist get the full picture and watch the response when they wind up the pressure.

I would imagine that a bigger problem is not that NO2 goes into the bubbles that are currently causing a problem, but that it goes into the smaller bubbles that aren't currently causing a problem. This could then grow them and cause more problems.

However I'm not a hyperbaric specialist, so might be completely wrong.

John
 

·
Shipwrecked & Comatose, drinking fresh mango juice
Joined
·
2,614 Posts
It might seem mean but I would be very hesitant to administer any pain relief to a DCS patient. Let the hyperbaric specialist get the full picture and watch the response when they wind up the pressure.
When I went for a trip to the chamber at Whipps Cross (I'd recommend anyone to go, before they may "have" to go) that for them was more important than any ongassing that may take place.

It may be a bit cruel, when someone is in agony, but in the long run it may work out safer.

I am not a doctor so my advice is worth exactly as much as you paid for it.
 

·
Registered
Joined
·
233 Posts
Discussion Starter · #6 ·
Hi
I'm waiting for a reply from a hyperbaric specialist - fingers crossed. There was an interesting thread on here a while ago about entonox and wearing 'medi tags' which made me laugh out loud. They seemed to be under the impression that you can be 'given' entonox when you are unconscious or without a choice in the matter.
It is probably worth clearing up that entonox is a SELF-ADMINISTERING ANALGESIC AGENT....If you do not have the capacity to understand what it is, it's side effects or how to take it properly, then you cannot use it. A paramedic or a tech will not give it to someone who does not have the capacity to say "I went diving yesterday" !!!
So fear not!:)

I was under the impression that nitrous oxide would enlarge the smaller (micro) bubbles in the fluids and tissues thus exacerbating the problem. But I'll wait to see what this guy says about it.
Thanks for the responses.
Chris
 

·
Registered
Joined
·
233 Posts
Discussion Starter · #7 ·
p.s Another interesting point about it is that, ironically, putting aside the diving factor for a second, entonox is ideal for some pain relief because it wears off completely seconds after you stop breathing it. So, if I wanted to find out what a patients 'real' pain score was, I'd simply take the gas off them and wait for a minute and then ask them !! In that respect it would be ideal, if it weren't harmful.


p.s I'm not always that mean !! :angel:
 

·
00.00 hrs
Joined
·
905 Posts
Cgrosart,

I know that it easier to explain the effect of lodged inert gas bubbles in the system as a bubble blocking the flow of blood, indeed this will happen to a certain extent. However, the main reason for the reduced gas exchange between the tissues and the blood is the fact that micro-bubbles have caused scarification of the internal walls of the arteries and veins.

This is why 100% O2 works so well as it allows the undamaged surface area to exchange as much gas as possible and the gradient is heavily biased in-favour of on gassing O2 and off gassing N.

There are a number of reasons why Entonox can excaserbate the problems but the simple mathematics will give you the first hint. Entonox normally is made up of 50% Nitrous Oxide and 50% O2, ie. the actual level of O2 is not as good as it could be with 100% O2.

In addition Nitrous Oxide is an asphyxiant in the absence of Oxygen, hence the 50% O2 in Entonox, and will begin to introduce hypoxia (ie. the gradient is reversed).

In short, the very minor benefit of using Entonox (ie. short term pain relief) is far outweighed by the disruption to the effective decompression of the body, that it would cause.

Again, no medical qualifications so take what you want from the above and check it!!

Regards
Safe Diving
Midnight
 

·
Registered
Joined
·
2,451 Posts
I don't see 'rapidly'.
Nitrous is highly lipid soluble. Apart from the analgesic use, it is also used as a mixing agent for oily compounds and whipped cream. It moves through cell membranes very easily hence it acts rapidly when used as an analgesic. This same property contra-indicates Nitrous for ALL barotrauma injuries.

If a bubble is lodged it must be blocking the blood flow or it would be in inert gas poor tissue and be off gassing so it isn't actually going to get much NO2 but it's pushing in the wrong direction.
N2O (Di Nitrogen Oxide) is a compound in it's own right. It just happens to be a Nitrogen based compound. The body does not metabolise it so it comes out pretty much exactly as it goes in. It's lipid solubility allows it to move through cells with relative ease hence it per-fuses the body tissues and migrates into cavities and air spaces rapidly. It is about 40 times more soluble in blood than Nitrogen.

Entonox should not be administered to anyone that has been diving within the last 24Hrs irrespective of symptoms.

I forget how NO2 works, I think it's a brain addler (intoxicant) rather than a tissue site-specific pain killer so I can see how it might be suggested for DCS pain where compromised blood flow makes delivery to a site is problematic.
NO2 (Nitrogen Di-Oxide) is a pollutant which forms at high temperatures and has no medical application that I am aware of. Entonox is a mixture of 50% N2O Di-Nitrogen Oxide) and 50% O2 (Oxygen). The Oxygen is added to stop the patient expiring from hypoxia. Like a lot of anaesthetics, they don't know how it works. It causes chemical changes in the brain and spinal chord which are thought to affect Neuron activity.

It might seem mean but I would be very hesitant to administer any pain relief to a DCS patient. Let the hyperbaric specialist get the full picture and watch the response when they wind up the pressure.
Completely agreed. Oxygen and Water are really the only things you should give to a DCS victim. Once pain killers enter the equation it becomes impossible for the chamber doc to properly assess the casualty and may restrict the treatment they can provide...According to a HBOT doc I talked to after a suspected bends case was shot in the arm with Morphine by the local A&E department! We managed to stop the paramedics administering Entonox on the beach but they were off to A&E before we had the guys kit off the boat.
 

·
Registered
Joined
·
233 Posts
Discussion Starter · #12 ·
Hi
Some very interesting points. Just to clarify, I'm not suggesting Entonox should EVER be given to bends victims - rather just exploring the reasons WHY.
On a different tack - there seems to be a huge fear across the net that paramedics and techs are trying to give bends victims entonox. It clearly states in our drugs procedures that this is CONTRA-INDICATED. If we break these guidelines, it is disciplinary action. Either there are a load of incompetent paramedics out there (unlikely, judging by the calibre of my colleagues) or this fear has been borne from one incident and spread.
Further more, Entonox HAS to be self administered so a diver would have to voluntarily and knowingly breathe the stuff themselves in order to get it on board.
Perhaps some more diver education, maybe ?
A suspected DCS casualty should never be offered entonox and if they were, should know not to use it. 100% oxygen and re-hydration should be the immediate concern, followed by hyperbaric treatment.
Just out of interest, why was the diver in the above scenario taken to A&E and not the chamber ?
 

·
Registered
Joined
·
7,598 Posts
Hi
Some very interesting points. Just to clarify, I'm not suggesting Entonox should EVER be given to bends victims - rather just exploring the reasons WHY.
On a different tack - there seems to be a huge fear across the net that paramedics and techs are trying to give bends victims entonox. It clearly states in our drugs procedures that this is CONTRA-INDICATED. If we break these guidelines, it is disciplinary action. Either there are a load of incompetent paramedics out there (unlikely, judging by the calibre of my colleagues) or this fear has been borne from one incident and spread.
Further more, Entonox HAS to be self administered so a diver would have to voluntarily and knowingly breathe the stuff themselves in order to get it on board.
Perhaps some more diver education, maybe ?
A suspected DCS casualty should never be offered entonox and if they were, should know not to use it. 100% oxygen and re-hydration should be the immediate concern, followed by hyperbaric treatment.
Just out of interest, why was the diver in the above scenario taken to A&E and not the chamber ?
UK protocols?
Who says it's just UK?

Divers have a habit of going all over the world and dont know about you,
but having the one mantra that says "no Entonox" is a damn site better
than trying to go through a country list of those that do know and those
that dont.

What's the worse case? Paramedics saying "we know" while rolling eyes.
Rather have that then get it wrong.
 

·
Registered
Joined
·
233 Posts
Discussion Starter · #15 ·
Thanks for your constructive comments.

The original question was to explore what actually happens or could actually happen if entonox was given to a casualty with DCS. Having done some research today, there seems to be a number of different consequences, enough for me to construct a useful exam question, though I may need to alter the format somewhat. Some of the above posts were very interesting. Thankyou.
 

·
the kind of human wreckage that you love
Joined
·
11,983 Posts
I will be very interested to hear what response you get from the hyperbaric medical chap/team

I have heard that, while entonox may not be the preferred pain killer, if a pain reducing agent is needed it could be considered quite handy, given that it provides 50% O2. In the same conversation I understood that all the panic about a diver having been diving was quite possibly myth.

All a bit confusing, given all the teaching of "no Entonox" so I'm keen to hear what the experts say. Please do update this thread when you hear, thanks
 

·
Registered
Joined
·
164 Posts
Just a thought.

If I had been diving previously could Entonox possibly give me a bend even if previously not bent? So the question may not have to be to DCS in general but about a diver who has subsequently had an accident?
 

·
Irish Cave Diver in the making
Joined
·
3,241 Posts
On a different tack - there seems to be a huge fear across the net that paramedics and techs are trying to give bends victims entonox. It clearly states in our drugs procedures that this is CONTRA-INDICATED. If we break these guidelines, it is disciplinary action. Either there are a load of incompetent paramedics out there (unlikely, judging by the calibre of my colleagues) or this fear has been borne from one incident and spread.
Some time ago, I had to be taken to hospital in an ambulance and was in a lot of pain. (Not dive related) But I had been diving the previous day. I was ready to refuse Entonox should it be offered to me. The paramedics would not have known that I was a diver nor that I had recently been diving, but I did.


Just out of interest, why was the diver in the above scenario taken to A&E and not the chamber ?
Sorry, I obviously skimmed the 'scenario' as I don't know which one you are talking about :redface: But, as far as I am aware you are taken to Triage as a 'doctor' has not assessed your medical condition. Some divers may be excellent at diagnosing DCI, but the medical profession can hardly just take the word of every person who calls in a diver injury as to what is wrong with them when there are no external signs e.g. lower leg cut off by a prop etc. So, you are examined like every other accident.
.
 

·
Registered
Joined
·
2,451 Posts
rather just exploring the reasons WHY.
Dalton's Law.

On a different tack - there seems to be a huge fear across the net that paramedics and techs are trying to give bends victims entonox. It clearly states in our drugs procedures that this is CONTRA-INDICATED. If we break these guidelines, it is disciplinary action. Either there are a load of incompetent paramedics out there (unlikely, judging by the calibre of my colleagues) or this fear has been borne from one incident and spread.
That is very strongly worded. Diving incidents are sufficiently rare that medical professionals are not going to come into contact with them routinely. Both my parents worked in the NHS for over 40 years and never came across a diving disorder. In comparison I have been diving for about 1/4 of that time and have witnessed around a dozen incidents that required medical attention. Entonox is something I am aware of only because I dive routinely. Is it SOP for paramedics to check the paperwork before administering each and every drug. If it is then some may judge them incompetent. Personally I would say they are just as human as the rest of us.

Further more, Entonox HAS to be self administered so a diver would have to voluntarily and knowingly breathe the stuff themselves in order to get it on board.
Perhaps some more diver education, maybe ?
A suspected DCS casualty should never be offered entonox and if they were, should know not to use it. 100% oxygen and re-hydration should be the immediate concern, followed by hyperbaric treatment.
More diver education would not hurt. I don't think it is safe to rely on the casualty though. They are likely to be shaken up and may not clearly remember what has just happened let alone something they heard mentioned briefly in a lecture. From what I have seen most injured people go along with whatever the medical professionals suggest.

Just out of interest, why was the diver in the above scenario taken to A&E and not the chamber ?
No idea. Hopefully nothing to do with arse covering, performance targets or cross trust charging.

The handling was all a bit pants really. The casualty was taken off O2 so he could walk up quite a steep beach. The paramedics were prepping an Entonox bottle by the time I got to the ambulance. I mentioned that I didn't think it was supposed to be given to divers and they broke the set down and put it away. I was sorting out the loose ends which sometimes get overlooked after these incidents. Retreiving the divers kit from the boat, checking what time the car park shut, that sort of thing. I followed up the ambulance to make sure the casualty and his buddy were not going to find themselves stranded miles from home in the middle of the night at the end of a chamber ride. It was a surprise to hear they had been taken to A&E, the chamber was about 30 minutes away.

When I got to A&E the casualty was on his way to the chamber but I was shocked to hear he had been pinned with morphine. The lead nurse seemed to think that they would blow him down to 30m and keep him in overnight. There was no point in having an argument about it so I just stopped listening at that point. The buddy was not transferred to the chamber but was kept in overnight, which is again a little unusual.
 

·
Registered
Joined
·
233 Posts
Discussion Starter · #20 · (Edited)
Hi
Sorry for the delay.
Right.
Spoke to the guy who works in hyperbaric medicine and also used to be a paramedic. I know he is kosher because he treated one of my friends in a chamber when he got bent a couple of years ago.
Basically, there a lot of myths about entonox amongst divers which are akin to chinese whispers and I will help to put them straight if I can.
Entonox is a GAS not an injection (as someone queried via PM)
It is made up of 50% nitrous Oxide and 50% Oxygen.
This much we know.
In the case of a diver who is KNOWN to be 'bent' or SUSPECTED to have some sort of Decompression illness or queried effects after a dive - ENTONOX MUST NOT BE GIVEN. The reason is simply that it is LIKELY (though not definately) to enlarge EXISTING BUBBLES in the tissues and fluids of the body.

If a diver misses a deco stop - DO NOT GIVE ENTONOX
If a diver shows ill or unusual effects after a dive DO NOT GIVE ENTONOX

If you are driving home after a day's diving and you have not missed any deco or have any reason to think you are bent or may be bent - and you crash the car......YOU CAN RECEIVE ENTONOX ----HOWEVER - due to CURRENT ambulance protocals, we cannot give it to you (because you have been diving in the last 24 hours)!!! So, even though you are in agony after the car crash and fine after the dive....You won't get it anyway !!! Yes, Paramedics and Techs (who can also administer the gas) may overlook the diving thing - and they have every right to do so in your best interests. The important point is here - Entonox will not MAKE you bent if you have NO HARMFUL NITROGEN BUBBLES to enlarge. If you have had a safe dive, you are no more at risk than the little old lady who tripped over the plant pot (having not been diving !!) by having entonox. The ambulance service are covering their arse (please remember that paramedics and techs do not make the rules - our bosses do ) by not permitting entonox 24 hours after diving - regardless of any DCS symptoms. The advice I got from the hyperbaric guy was to give it anyway (with absent symptoms or suspicion of DCS) so long as you can justify it - which I could. In that, I am treating a car crash casualty, not a bent diver.
Morphine is a pain in the arse as it does not reverse quickly but there are no associated dangers related to DCS other than a chance of respiratory depression, which is the same with everyone who receives morphine.
I enquired on a slightly different tack about the use of morphine at depth (should it ever be required in a cave diving rescue scenario - i.e getting someone back home through a sump). The reply was that it was NOT GOOD (as I suspected) and respiratory arrest could occur at depths as shallow as 18metres. Interesting ; should you receive morphine and then have to go into a pot............
But basically, entonox isn't as scary as it appears. It won't help a bend and may enlarge existing bubbles. It probably wouldn't kill you, but may delay recovery or lengthen treatment and could worsen pain, especially in joints.
It is still, rightly, contra-indicated as pain relief in bends victims. But I think most people would be rather pissed off if they had a successful, incident-free, no-decompression days diving and then crashed the car. You would (by the book) be refused any pain relief whatsoever (even though you had no nitrogen bubbles to enlarge).
I can't give you a solution to this, save one (tongue in cheek) - If you suffer any ill effects or miss deco or think you could be bent.
DON'T drive home - get checked out.
Common sense you may think, but not all divers have it.
If I think of anything else he said, I'll post later.
It was very interesting stuff, especially as we touched on ppO2 limits and the myths behind those. I learned a lot today. And got the answers I wanted.
I did type this very quickly so apologies if it appears blunt - been at work all day, just got in.
Cheers
Chris
 
1 - 20 of 23 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top