Guest guest Posted January 1, 2002 Report Share Posted January 1, 2002 Can anyone give me their thoughts on whether or not O2 is an immediate first aid treatment for CNS toxicity as some diving agencys contradict others. Thanks DW Quote Link to comment Share on other sites More sharing options...
Guest guest Posted January 1, 2002 Report Share Posted January 1, 2002 On Tue, 1 Jan 2002 22:47:34 -0000, you wrote: >Can anyone give me their thoughts on whether or not O2 is an immediate first aid treatment for CNS toxicity as some diving agencys contradict others. > >Thanks >DW By CNS toxicity do you mean CNS oxygen toxicity? If so, the high O2 level is the cause - so it must be reduced. Who says otherwise? Immediately giving more O2 to someone suffering from its toxic effects doesn't make sense at all. What scenario are you referring to? Sat divers, SCUBA divers, rebreather divers, what O2% at what pressure, in a therapy chamber, etc? Stuart ITU & Hyperbaric Nurse / Medic www.hyperchamber.com Quote Link to comment Share on other sites More sharing options...
Guest guest Posted January 2, 2002 Report Share Posted January 2, 2002 If your pt / diver's gas was 100% O2 and was convulsing then some would say let the toxicity wear off. If he is convulsing then the O2 will be metabolised very quickly. O2 is toxic at increased partial pressure. (Eventually 100% O2 at sea level will also have pulmonary toxicity effects unit of pulmonary toxic dose UPTD ~ 1425 mins or 24 hours). In short, if O2 CNS tox was the only problem I was faced with at the surface then I would use O2. In my experience the O2 CNS ( Bert effect) wears off rapidly. Problem you are faced with however, may be compounded by pulmonary emboli especially if this diver has ascended during the 'tonic' phase of the convulsion, and what you are actually faced with is neuro DCI. Funnily enough the treatment for this is ......O2. Regards Ian H Quote Link to comment Share on other sites More sharing options...
Guest guest Posted January 2, 2002 Report Share Posted January 2, 2002 Ian H Quote Link to comment Share on other sites More sharing options...
Guest guest Posted January 2, 2002 Report Share Posted January 2, 2002 In the majority of scuba diving accidents the breathing gas will be air, 20:80 Oxygen / nitrogen mix, there is no real likelihood of CNS O2 tox as the nitrogen narcosis will have claimed you long before this occurs. O2 toxicity is generally quoted at pressures in excess of 3ATA. within a hyperbaric chamber, indeed this is why there have to be air breaks during the treatments that use 100% O2 at depth, RNTT62, Comex 30, USN 18 mtr tables, etc. In water however, I have seen a diver take an O2 hit at 4msw when swimming hard (1.4ATA). The diver using O2 to blow off Nitrox mix is at an increased risk of the O2 hit if he is having to swim against the tidal flow, etc. sometimes this ends in disastrously for the diver, more so if using a split rig (separate dv and mask). The military have written up a case of pulmonary barotrauma (PBT) from just one metre of ascent so again I would be hard pushed to separate a PBT from CNS O2 hit in the unconscious, convulsing diver, and would use O2 at the surface. CNS O2 tox does not occur at 1ATA, (unless the pt/diver are taking drugs that compete with the body's ability to cope with the 'free radicals' (chemicals) that oxygen causes the body to release normally). Not too many of these types are fit enough to dive though. It is these free radicals that cause the O2 hit, they are produced usually at >1ATA, the 'new' oxygen at the surface is unlikely to contribute to the manufacture of new free radicals. O2 hits within the hyperbaric chamber are about 1:10,000 treatments and I have seen 3, & dealt with 2, it is a different environment the PO2 is around 2.8ATA and the patient / diver is at rest. The hit subsides usually within 30 ~ 60 secs, if we are still within an O2 period then we would wait for 15 mins (breathing air) and put the diver back on O2, this can be repeated up to 3 times. In water PO2 should ideally, not be at these levels. What sort of dive profiles are you doing, & what PO2 are you using for in water deco? Ian H Quote Link to comment Share on other sites More sharing options...
Guest guest Posted January 2, 2002 Report Share Posted January 2, 2002 It is CNS oxygen toxicity I was referring to, I am a BSAC advanced nitrox instructor and an SSI nitrox instructor. The British sub aqua club state that the Administration of 100% O2 following an O2 hit is not recommended, but Scuba schools international recommend it as a immediate first aid treatment. Sorry if I was not clear but it is aimed at scuba divers. The pressure of O2 would be at 1bar. Regards DW Re: CNS toxicity > On Tue, 1 Jan 2002 22:47:34 -0000, you wrote: > > >Can anyone give me their thoughts on whether or not O2 is an immediate first aid treatment for CNS toxicity as some diving agencys contradict others. > > > >Thanks > >DW > > By CNS toxicity do you mean CNS oxygen toxicity? > > If so, the high O2 level is the cause - so it must be reduced. Who > says otherwise? Immediately giving more O2 to someone suffering from > its toxic effects doesn't make sense at all. > > What scenario are you referring to? Sat divers, SCUBA divers, > rebreather divers, what O2% at what pressure, in a therapy chamber, > etc? > > Stuart > ITU & Hyperbaric Nurse / Medic > www.hyperchamber.com > > > Member Information: > > List owner: Ian Sharpe Owner@... > Editor: Ross Boardman Editor@... > > Post message: egroups > Subscribe: -subscribeegroups > Unsubscribe: -unsubscribeegroups > > Thank you for supporting Remote Medics Online. > > > > > Quote Link to comment Share on other sites More sharing options...
Guest guest Posted January 2, 2002 Report Share Posted January 2, 2002 Hi Dean, I've been having a look for a decent reference for you but so far have come up dry (forgive the pun) My knowlege of diving medicine is limited but I would have though that a diver having had a CNS oxygen toxicity hit. My initial thoughts would be to ween the guy off the oxygen back to room air (assuming he had surfaced) but trying to maintain a decent pulse ox. The only reason I can think of for Scuba Schools recomendation of 100% O2 is possibly in the case of an unsure diagnosis but for specific CNS o2 toxicity I would have though you would wish to bring the patient off the O2. I have cross posted your message to one of the internet dive medicine forums, so maybe we'll have a reply in a couple of days. Comments Stu, You're the resident expert ! :-) Best Wishes ian Listowner Re: CNS toxicity It is CNS oxygen toxicity I was referring to, I am a BSAC advanced nitrox instructor and an SSI nitrox instructor. The British sub aqua club state that the Administration of 100% O2 following an O2 hit is not recommended, but Scuba schools international recommend it as a immediate first aid treatment. Sorry if I was not clear but it is aimed at scuba divers. The pressure of O2 would be at 1bar. Regards DW Re: CNS toxicity > On Tue, 1 Jan 2002 22:47:34 -0000, you wrote: > > >Can anyone give me their thoughts on whether or not O2 is an immediate first aid treatment for CNS toxicity as some diving agencys contradict others. > > > >Thanks > >DW > > By CNS toxicity do you mean CNS oxygen toxicity? > > If so, the high O2 level is the cause - so it must be reduced. Who > says otherwise? Immediately giving more O2 to someone suffering from > its toxic effects doesn't make sense at all. > > What scenario are you referring to? Sat divers, SCUBA divers, > rebreather divers, what O2% at what pressure, in a therapy chamber, > etc? > > Stuart > ITU & Hyperbaric Nurse / Medic > www.hyperchamber.com > > > Member Information: > > List owner: Ian Sharpe Owner@... > Editor: Ross Boardman Editor@... > > Post message: egroups > Subscribe: -subscribeegroups > Unsubscribe: -unsubscribeegroups > > Thank you for supporting Remote Medics Online. > > > > > Quote Link to comment Share on other sites More sharing options...
Guest guest Posted January 2, 2002 Report Share Posted January 2, 2002 The dive profiles are within sport diving with an MOD of varying depths dependant on the FO2, the bottom mix is set at a PPO2 of 1.4bar with a PPO2 of 1.5bar for the deco mix.The dives are around an hour in total with a maximum of 3 dives per day. DW Re: CNS toxicity > In the majority of scuba diving accidents the breathing gas will be air, > 20:80 Oxygen / nitrogen mix, there is no real likelihood of CNS O2 tox as the > nitrogen narcosis will have claimed you long before this occurs. > > O2 toxicity is generally quoted at pressures in excess of 3ATA. within a > hyperbaric chamber, indeed this is why there have to be air breaks during the > treatments that use 100% O2 at depth, RNTT62, Comex 30, USN 18 mtr tables, > etc. > > In water however, I have seen a diver take an O2 hit at 4msw when swimming > hard (1.4ATA). The diver using O2 to blow off Nitrox mix is at an increased > risk of the O2 hit if he is having to swim against the tidal flow, etc. > sometimes this ends in disastrously for the diver, more so if using a split > rig (separate dv and mask). > > The military have written up a case of pulmonary barotrauma (PBT) from just > one metre of ascent so again I would be hard pushed to separate a PBT from > CNS O2 hit in the unconscious, convulsing diver, and would use O2 at the > surface. CNS O2 tox does not occur at 1ATA, (unless the pt/diver are taking > drugs that compete with the body's ability to cope with the 'free radicals' > (chemicals) that oxygen causes the body to release normally). Not too many > of these types are fit enough to dive though. It is these free radicals that > cause the O2 hit, they are produced usually at >1ATA, the 'new' oxygen at the > surface is unlikely to contribute to the manufacture of new free radicals. > > O2 hits within the hyperbaric chamber are about 1:10,000 treatments and I > have seen 3, & dealt with 2, it is a different environment the PO2 is around > 2.8ATA and the patient / diver is at rest. The hit subsides usually within > 30 ~ 60 secs, if we are still within an O2 period then we would wait for 15 > mins (breathing air) and put the diver back on O2, this can be repeated up to > 3 times. > In water PO2 should ideally, not be at these levels. What sort of dive > profiles are you doing, & what PO2 are you using for in water deco? > > Ian H > > > Quote Link to comment Share on other sites More sharing options...
Guest guest Posted January 2, 2002 Report Share Posted January 2, 2002 Thanks for all the words of wisdom from the group DW Re: CNS toxicity > > > > On Tue, 1 Jan 2002 22:47:34 -0000, you wrote: > > > > >Can anyone give me their thoughts on whether or not O2 is an immediate > first aid treatment for CNS toxicity as some diving agencys contradict > others. > > > > > >Thanks > > >DW > > > > By CNS toxicity do you mean CNS oxygen toxicity? > > > > If so, the high O2 level is the cause - so it must be reduced. Who > > says otherwise? Immediately giving more O2 to someone suffering from > > its toxic effects doesn't make sense at all. > > > > What scenario are you referring to? Sat divers, SCUBA divers, > > rebreather divers, what O2% at what pressure, in a therapy chamber, > > etc? > > > > Stuart > > ITU & Hyperbaric Nurse / Medic > > www.hyperchamber.com > > > > > > Member Information: > > > > List owner: Ian Sharpe Owner@... > > Editor: Ross Boardman Editor@... > > > > Post message: egroups > > Subscribe: -subscribeegroups > > Unsubscribe: -unsubscribeegroups > > > > Thank you for supporting Remote Medics Online. > > > > > > > > > > Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You are posting as a guest. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.