Unconscious diver

[Scuba]

I have moved these questions here from the thread "Rescue and buoyancy control" http://www.scubaboard.com/t18780/s.html in the Ask Dr Deco section, since they are medical in nature.

The questions below refer to a diver who has received an oxygen toxicity hit and is or appears unconscious.

Is it possible to identify wether a diver who appears to be unconscious is in fact unconscious or in a tonic state? One will have his airway open the other possibly shut.

Is there a simple manuver, such as subdiaphragmatic abdominal thrusts given in a choking situation, that could be administered to open the airway if it is shut.

Could this or other manuver, or a modification of it, at least release some gas decreasing the chance of pulmonary overpressure problems and making immediate controlled surfacing procedures possible?

Could this manuver cause more harm the good or have negligible value?

If this or another procedure is helpful, would applying it to an unconcious diver with open airway cause additional harm?

 

[BillP]

Interesting questions, Scuba. Loss of consciousness underwater from any cause is of course a very risky business. Loss of consiousness from an oxygen toxicity induced seizure introduces the additional problem of a closed airway that would prevent escape of expanding air on ascent leading to an arterial gas embolism. So what do you do?

I beleive that most authorities would recommend that you not bring a diver to the surface while they're having a seizure, but usually when you read these recommendations they are talking about a seizure in a hyperbaric chamber or in a commercial diver with a helmet. I would suppose that if an open circuit scuba diver were to retain his regulator in his mouth the recommendation still holds, but what if the diver loses his regulator? Is it better to die from an arterial gas embolism or drowning? Dunno the answer to that one.

Scuba asked...

Is it possible to identify whether a diver who appears to be unconscious is in fact unconscious or in a tonic state? One will have his airway open the other possibly shut.

Divers in a tonic state from an oxygen toxicity induced seizure will be unconscious. The diver in a tonic state will be rigid or possibly twitching/jerking.

Scuba asked...
Is there a simple manuver, such as subdiaphragmatic abdominal thrusts given in a choking situation, that could be administered to open the airway if it is shut.

Could this or other manuver, or a modification of it, at least release some gas decreasing the chance of pulmonary overpressure problems and making immediate controlled surfacing procedures possible?

Could this manuver cause more harm the good or have negligible value?

The way subdiaphragmatic abdominal thrusts open the airway in a choking situation is to increase the pressure in the lungs (that pulmonary overpressure problem you mentioned) so much it dislodges the food in the airway. That increased pressure would not open the airway in a tonic seizure any more than an ascent to the surface would, and I would not recommend trying it. In your rescue diver class you probably learned the head tilt/jaw thrust (or similar) maneuver to open the airway, but this only works in the unconsious relaxed diver. I don't know of any simple maneuver to open the airway in a tonic/seizing diver. I beleive you're right, to try a maneuver like abdominal thrusts would be of negligible value and likely do more harm than good.

Scuba asked...
If this or another procedure is helpful, would applying it to an unconcious diver with open airway cause additional harm?

Yeah, you can potentially break ribs, rupture diaphrams, perforate bowel, etc. with various procedures so you need to weigh the potential risks vs. benefits in the particular situation. IMHO, I would not try to do a Heimlich or similar procedure on another diver underwater.

HTH,

Bill

 

[Scuba]

Thank you for replying BillP, a few more questions, if I may.

Is a totally unconscious diver (beyond tonic) always relaxed, not rigid or twitching, and will his airway always be open?

Is an unconcious tonic state diver always rigid or possibly twitching/jerking, and will his airway always be shut?

Any practical way to identify in these divers whether airway is open or shut?

 

[BillP]

Scuba asked...

Is a totally unconscious diver (beyond tonic) always relaxed, not rigid or twitching, and will his airway always be open?

No, the airway will not always be open. That's why they teach that head tilt/jaw thrust maneuver (or similar technique) to open the airway for the relaxed unconscious patient in the CPR/rescue class. The difference between the tonic and relaxed unconsious diver is that in the relaxed unconscious person the glottis (sound producing mechanism of the larynx) will almost always be relaxed, and in the tonic person it will generally be forcefully closed by the spasms of the seizure. It is that forceful spasmodic closure of the glottis in a seizure that raises the concern about having enough airway obstruction to cause barotrauma and arterial gas embolism on ascent. In the relaxed unconscious diver it is generally assumed that expanding air will be able to bubble past the relaxed throat structures on ascent.

Scuba asked...
Is an unconcious tonic state diver always rigid or possibly twitching/jerking, and will his airway always be shut?

Always? People having seizures will sometimes "grunt" indicating some air is getting through their glottis, but I would assume a closed glottis in a tonic (rigid) or clonic (twitching/jerking) diver.

Scuba asked...
Any practical way to identify in these divers whether airway is open or shut?

Yes, there is an easy way to tell if the airway is open. If the diver is breathing the airway is definitely open. (Hey, you didn't ask if there was a good practical way ;-) Other than that, you assume the airway might be obstructed in the unconscious person. At depth, if the diver is tonic or clonic I would assume a spasmodically closed airway. If the diver is flaccid I would have to assume an airway open enough to allow expanding air to escape on ascent. Those assumptions might be wrong in certain cases, but you can't really do a head tilt/jaw thrurst/rescue breaths (mouth to mouth resuscitation) at depth to see if the airway is really open.

HTH,

Bill

The above is intended for discussion purposes only and is not meant as specific advice for any individual.

 

[scubadoc]

Hi Scuba and BillP!

Very interesting discussion that is not addressed to a great degree in any of the texts, and certainly not written about in the medical journals except to report fatalities in tech divers.

Edmonds et al in their 4th Edition, simply state that the convulsing diver should not be brought to the surface while seizing.

NOAA does not address the issue at all [that I can find], nor does Bove.

There is a description of rescue of the convulsing diver in the new book, "On-site Management of Scuba Diving and Boating Emergencies", by Wesley Y. Yapor, MD, p. 111-112. In the section, they recommend that the very first priority is getting the diver out of the water as safely as possible. Proper ascent is required to protect the rescuer after the seizure has ceased. The regulator is placed in the victims mouth, purged and held with the right hand. He suggests thatthe chest be squeezed firmly once or twice in an effort to get out as much water as possible. During ascent the victims jaw should be extended to open the airwayand allow air to escape from the lungs. The normal recoil of the chest wall will function as a bellows.

This does not address a method to ascertain if there is a tonic, closed glottis. One has to assume that is tonic-clonic convulsion has stopped - then there is relaxation of the larynx and the glottis is open.

Any way you cut it, you need to get the victim to the surface for further adequate rescue. Two things will occur:
1. The PPO2 will fall as you ascend, reducing the risk of further seizures and,
2. You will get the victim out of the extremely hostile environment of the underwater milieu so that recompression treatment can be provided as necessary and hospital intensivists can take over in treating the near drowned victim.

Interesting debate!

 

[Scuba]

Given that every second is precious in an emergency rescue situation such as the one being described, any guidelines on the duration of a "tonic state", in cases where it is caused by an Ox-Tox hit.

In the event where the diver is not breathing, and there is a prolonged (if possible) recognizable seizure state, how long should the assisting diver who has witness the onset, or can fairly accurately calculate the onset of the seizure, (saw buddy 15 seconds ago OK and now he is seizing) wait for seizure to subside before the risks associated with surfacing become less or comparable to the risk of staying down?

Not intended to place the doctors on the spot. but any guidelines you can offer based on your medical knowledge is appreciated. I have no doubt you will offer "good", practical guidelines, BillP, and company.

 

[Scuba]

Not even I will attempt to answer my question. But, I did find some information of relevance. Feel free to correct if needed.

A drowning victim should ideally start receiving resuscitation efforts withing 30 seconds. The longer the start of treatment, the lower the chance of success, and the greater the risk of additional complications. Colder water may provide additional time.

At aproximately 4 minutes without oxygen brain cells start dying increasing the risk of brain damage.

The tonic - clonic (rigid/twitching,jerking) state of a seizure (tipically?) last from a few seconds to 2 minutes, although it can last longer. Possibly 5 minutes?

In regards to the referenced book mentioned by scubadoc, where there is the mention of:

He suggests thatthe chest be squeezed firmly once or twice in an effort to get out as much water as possible.

I found a couple of articles that may be of interest to some, although you guys may have already seen them, since they are not new.

http://www.lvrj.com/lvrj_home/1997/Jul-01-Tue-1997/lifestyles/5368109.html

http://www.lifesaving.com/issues/articles/23heimlich_controversy.html

 

[The Iceni]

Hi Scuba,

Can I add my tuppence worth here? Many of you may know that I had a nasty diving accident back in November. I think it was an O2 hit but cannot be sure. In any case I was not brought to the surface for several minutes by which time, of course, I was hypoxic and deeply uncounscious.

No pulmonary barotrauma, thank goodness!

For what it is worth I would suggest that it would be extremely hazardous for the rescuer to attempt to make contact with a convulsing diver and it would be wise to wait until all signs of convulsions cease. First rule of first aid is not to become a casualty oneself!

NB; order of signs

1. Tonic - rigid phase with spasm of all muscles
2. Clonic - convulsive phase with alternating contraction/relaxation of muscle
3. Flaccid phase - simple unconsciousness - all muscles relaxed.
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   I hope this helps!

 

[boomx5]

You where really missed around here.

 

[Uncle Pug]

As you probably know... many of us were praying for you and it is really wonderful to see your post... welcome back! I thank God for answered prayer.