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Scuba Forum / General / January 2006Riddle me this: laryngospams
Ok, so I'm reading this DAN publication on managing dive accidents by Allan Kaynes. In the section re. surfacing an unconscious diver from deep, they mention that if the diver doesnt have a reg in his mouth (as is most likely going to be the case), then you can assume laryngospasms, whereby the larynx constricts to seal off the airway and prevent water from going in - and also air from escaping. They say that if you bring the diver up a little and you see no air escaping from his mouth, assume laryngospams - and wait till the spasms relax (which happens shortly before brain death, incidentally - so a very short window for resuscitation). The handbook clearly points out that surfacing an unconscious diver while they still suffer from laryngospams is likely going to cause "death due to massive barotrauma." Obviously, this is something that is not considered in most rescue classes, where it is "tilt head back and bring them up." Any experts on diving medicine care to comment on this? Vandit > Ok, so I'm reading this DAN publication on managing dive accidents by > Allan Kaynes. [quoted text clipped - 17 lines] > > Any experts on diving medicine care to comment on this? Either you let 'em drown, or risk barotrauma. Ya got me. But one way or another, they're coming up. And there's nothing you can do for them until they do. > Vandit > Obviously, this is something that is not considered in most rescue > classes, where it is "tilt head back and bring them up." > > Any experts on diving medicine care to comment on this? Damn, I always thought that this was one of the reasons we carried a dive knife -- impromptu trachiotomies at depth... >> Obviously, this is something that is not considered in most rescue >> classes, where it is "tilt head back and bring them up." [quoted text clipped - 3 lines] > Damn, I always thought that this was one of the reasons we carried a dive > knife -- impromptu trachiotomies at depth... I was going to make a joke about puncturing a lung... > I was going to make a joke about puncturing a lung... Great minds think alike, I guess... <snicker> >> I was going to make a joke about puncturing a lung... > > Great minds think alike, I guess... <snicker> :-) > Ok, so I'm reading this DAN publication on managing dive accidents by > Allan Kaynes. [quoted text clipped - 19 lines] > > Vandit That's Dr Allan Kayle, by the way. We asked some very reputable diving doctors to comment on Dr Kayle's opinion that: "surfacing an unconscious diver while they still suffer from laryngospams is likely going to cause death due to massive barotrauma." The reponse, after consultation with other diving doctors and anaesthetists, was that expanding air in the lungs on ascent would overcome the laryngospasm and allow the air to escape. The opinion is thus that pressure required to overcome laryngospasm is less than the pressure which would result in barotrauma. rgds monty > The opinion is thus that pressure required to overcome laryngospasm is > less than the pressure which would result in barotrauma. Damn, you mean I did that tracheotomy at depth for nothing? >> The opinion is thus that pressure required to overcome laryngospasm is >> less than the pressure which would result in barotrauma. > > Damn, you mean I did that tracheotomy at depth for nothing? Practice? Lee > The opinion is thus that pressure required to overcome laryngospasm is > less than the pressure which would result in barotrauma. Which can be definitely wrong. According the the medical leader of the pneumology group at Boehringer, Dr. Kay Tetzlaff, about 30 percent of leaving humans have a condition that would facilitate rupture of alveoli at pressures from 80mbar upwards. This has to be read with the knowledge that a strong cough can exceed 120mbar. Dr. Tetzlaff data result from his experience as a physician while in Eckernfoerde at the KSK, and later as the director of diving medizine at the German Navies Naval and Hyperbaric Medical Institute in Kiel. What sometimes is mixed up with laryngospasms, is the fact that the tongue can obstruct the airways as well. But take a tongues weight, and divide it by the crossectional area of the trachea, to see that the pressure necessary to lift the tongue is quite a bit less, and thus on the safe side. Which makes it obvious, that with an unconscious diver, the rescuer should _control_ the airways, by keepin the head straight, but not bend it towards the neck. This latter would facilitate water entry during the ascent, whenever there is a pause, or an unvoluntarily phase of sinking involved. Matthias I work as a Dive Medic and do frequent evacuations. >From the normal divers point of view - get the person to the surface and do everything you can to help. Try to perform rescue breaths as taugght on your rescue course) get them to the boat or land as soon as you can and try. Laryngospams do occur, they are a reaction in near-drowning (and therefore scuba accidents) that closes the larynx. If you try to do a rescue breath and it doesn't go in, reposition and try again. There is a slight chance that the person is expeiencing laryngospasms and that is why no air is entering thier lungs. That should not afffect your rescue. Keep trying. After the muscles burn off oxygen, the muscles will relax and the larynx will open. Then rescue breaths will be effecttive. A person underwater is in a foreign, life-threatening envrionment - get them out. A person on the boat can be treated efficently and usually with positive results. DAN is completely correct in saiyng that these do occur, but not in a way or as frequently as to afffecct the Lay persons rescue training. On the other hand, great job on actually reading the materials and considering the implications. > A person underwater is in a foreign, life-threatening envrionment - get > them out. A person on the boat can be treated efficently and usually > with positive results. DAN is completely correct in saiyng that these > do occur, but not in a way or as frequently as to afffecct the Lay > persons rescue training. Well, the book pretty much explicitly suggests waiting for laryngospasms to pass before ascending with the victim. And when a DAN publication unequivocally advocates something that is at odds with what most people are doing, makes me wonder. It strikes me that this might be asking too much of an average layperson, for starters - and that the standard "get them up asap" procedure might be simpler (barotrauma = repairable; death = not). A second thought I had was - if laryngospasm occurs when inhaling water, that implies that the diver has probably just exhaled prior to this. That, in turn, implies lungs that are at/near residual volume - ie, lower risk of serious barotrauma. Never had to do this yet. Am afraid that one of these days, I will. Would like to know the best thing to do, if and when this happens. Vandit > A second thought I had was - if laryngospasm occurs when inhaling > water, that implies that the diver has probably just exhaled prior to > this. That, in turn, implies lungs that are at/near residual volume - > ie, lower risk of serious barotrauma. Seems like a reasonable assumption, doesn't it? Most of my inhalations follow a reasonably complete exhalation, but every now and then I may inhale a bit even though I haven't exhaled thoroughly. Maybe I had a runny nose and sniffed a bit or maybe dinner smelled good and I sniffed a bit. Those are examples of an (abbreviataed) inhalation that was atypical. I suspect that a good rule of thumb with divers in distress would be to assume that the events leading to the distress were atypical. I was curious about Monty's statement that a laryngospasm wouldn't necessarily prevent the gas from escaping, so I did a brief Google search on "laryngospasm ascent barotrauma" (without the quotes). I found a coroner's report that's almost tailor-made to this discussion. The short version is that a woman on a resort course had trouble clearing her mask, panicked and "tore off her mask", bolted to the surface from about 30 feet, and died of barotrauma that appears to be related to laryngospasm. The full report is here: http://tinyurl.com/d28fl This is just my speculation, but the water in the mask might have caused her to inhale a small amount, triggering a laryngospasm causing her to start her panicky ascent with relatively full lungs.  SignatureSteve The above can be construed as personal opinion in the absence of a reasonable belief that it was intended as a statement of fact. If you want a reply to reach me, remove the SPAMTRAP from the address. >> The opinion is thus that pressure required to overcome laryngospasm is >> less than the pressure which would result in barotrauma. > > Which can be definitely wrong. The important questionis are can it be true, and what percentage of the itme will it be true. > According the the medical leader of the pneumology group at Boehringer, > Dr. Kay Tetzlaff, about 30 percent of leaving humans have a condition > that would facilitate rupture of alveoli at pressures from 80mbar upwards. 80 mBar is a bit over 1 psi, or half of the usual figure for the pressure at which alveloi will rupture, so it's somewhat usful to know, but what is the pressure required to overcome laryngospasm? If it's always more than 80 mBar that's bad news for the 30% if they find themselves ascending with a laryngospasm, but what about the other 70%? If we know that 70% of the time the expanding air will escape despite a laryngospasm, then we know that 70% of the time a direct ascent is definitely the proper choice. For the other 30% it's a tradeoff between risking barotrauma and risking drowning. Since we don't know who's in the 30% and who's in the 70% it would seem that waiting for the laryngospasm to subside is a major gamble. > This has to be read with the knowledge that a strong cough can exceed > 120mbar. Except as a reference, I don't see that as having any relevance. The mechanism of pressure resulting from a cough is a completely different than the mechanism of pressure resulting from expansion. When you cough, just as when you exhale normally, your muscles are compressing your lungs from the outside, so it's the pressure against the outside of the alveoli that raises the pressure on the inside. The pressure is balanced, so there won't be significant damage except in unusual cases. I would expect that when damage does occur in that manner that the resistance is often due to something other than the gas in the alveoli. SignatureSteve The above can be construed as personal opinion in the absence of a reasonable belief that it was intended as a statement of fact. If you want a reply to reach me, remove the SPAMTRAP from the address. > Ok, so I'm reading this DAN publication on managing dive accidents by > Allan Kaynes. The handbook clearly points out > that surfacing an unconscious diver while they still suffer from > laryngospams is likely going to cause "death due to massive > barotrauma." > > Vandit You need Spishaks: Vent-A-Buddy! It stores neatly into the handle of Spishaks: Bleed-A-Buddy anti shark device. Unlike the Bleed-A-Buddy which is designed to maximize outflow, the Vent-A-Buddy includes a one way purge valve to allow only off gassing once firmly seated in your buddy. > You need Spishaks: Vent-A-Buddy! > [quoted text clipped - 4 lines] > Vent-A-Buddy includes a one way purge valve to allow only off gassing > once firmly seated in your buddy. Damn Charlie, apparently there's hope for ya' yet... It's nice to find that you can still make rational posts when you have your tin foil hat on correctly... <grin> > Damn Charlie, apparently there's hope for ya' yet... While you and the rest of the Rec.Scuba Bund are lost for ever. >> Damn Charlie, apparently there's hope for ya' yet... > > While you and the rest of the Rec.Scuba Bund are lost for ever. Quote of the Day: "Rep. Mike Pence (news, bio, voting record), R-Ind., who appeared with Thune on "Fox News Sunday,", said all White House correspondence, phone calls and meetings with Abramoff "absolutely" should be released. 'I think this president is a man of unimpeachable integrity,' Pence said. 'The American people have profound confidence in him. And as Abraham Lincoln said, `Give the people the facts and republican governance perhaps will be saved.'" http://news.yahoo.com/s/ap/20060129/ap_on_go_pr_wh/bush_abramoff;_ylt=AnU1Febife ru7sHjghecHkSyFz4D;_ylu=X3oDMTA5aHJvMDdwBHNlYwN5bmNhdA-- "The American people have profound confidence in him." Talking about tin-foil hats. What planet is this guy from? Or rather, what planet are these Americans from that have profound confidence in Bush? > "Charlie" <keysclub@bellsouth.net> wrote in message > "The American people have profound confidence in him." Talking about > tin-foil hats. What planet is this guy from? Or rather, what planet are > these Americans from that have profound confidence in Bush? For profound confidence, The Deluxe Vent-A-Buddy comes equiped with a very powerful crystal which prevents excessive puncture depth while it protects your own personal karma. Your buddy will thank you for his intact lungs. |
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