drowning causes

[Dea]

Vaguely remember reading somewhere that a lot of drownings occur because a person inhales just a little water and than through involantary coughing he gets more and more. Which causes him to continue to cough, get more water and leads to drowning.
It that how it generally happens?
Is there anything to know about the drowning process that can prove useful?

Also, would a cramp prevent a swimmer from floating on his back?
(no wetsuit no fins scenario)

 

[TwoBitTxn]

Most drowning victims are discovered with very little water , about a teaspoon or so, in their lungs. This is due to the epiglottis or the muscle that controls it sealing off the trachea when water enters the lungs. Its an interesting reflex reaction, but it can also contribute to the death of the victim if it won't release when a rescuer is trying to get air in to the victims lungs.

TwoBit

 

[Dea]

wow!
a teaspoon? I wonder than why ocean swimmers are not dropping dead like flies...

 

[The Iceni]

Hi Dea and Twobit,

No links, I'm afraid.

I will try not to blind you with science but the usual cause of death in early drowning is simple asphyxia - an inability to move oxygen into the lungs and blood stream - and it has very little to do with how much water actually gets into the lungs. A drowned person's lungs need not be completely waterlogged and glottic spasm does play its part.

If I remember correctly there are at least three forms of drowning, fresh water downing, sea water drowning and secondary drowning (usually caused by fresh water).

So little water actually needs to reach the lungs and what little finds its way there, and the reason so little water is found in the lungs post mortem (particularly with fresh water drowning), is it is mostly absorbed by the blood stream. This is why you can inhale a "mouthful" and still breath quite normally afterwards and suffer no ill effects.

If sufficent fresh water is inhaled (after many hours fighting to stay afloat for example) it can dilute the blood so much that the red blood cells expand by osmosis and rupure, releasing the haemoglobin into the plasma. For reasons I do not fully understand, haemogolbin cannot funtion properly in plasma perhaps because so much of it gets stuck in the kideys the victim becomes severely anaemic.

I believe this is the cause of secondary drowning - again an inablity of the respiratory and circulatory system to deliver life-giving oxygen to the tissues.

I hope this is not only accurate but helpful.

By the way did you know that the main cause of death after shipwreck is not drowning but hypothermia? Modern life jackets are designed to keep the (unconcious) body "head up". Cramp is usually one sided, so that side does not work properly and the person simply cannot adjust his position voluntarily. This is why many BC manufactures claim to provide such a "head-up" position.



:doctor:

 

[ScubaJorgen]

Secundary drowning is caused by water inhaled during the first near-drowning. This water dissolves the lining of the lungs called surfactant. This surfactant stuff normally prevents the alveoli (cavities making up the lungs) from collapsing during the breathing process: it prevents the walls of the alveoli (and brancheoles?) from sticking together. Secondary drowning causes the alveoli to collapse, leading to malfunctioning of the lungs :drown:. Therefor anyone rescued from drowning needs medical attention, no matter how well he feels.

I read somewhere that smoking :rasta: deteriorates surfactant as well, though I never heard anyone suffer from secondary drowning from smoking. Does anyone have comments?

The secondary drowning somewhat contradicts the disolving-of-water-into-the-blood theory of Paul Thomas. If water gets dissolved into the blood, it is not supposed to dissolve surfactant. Furthermore, if osmosis is involved, you would expect fresh water to be dissolved into the blood, inflating bloodcells. You would expect secondary drowning with salt water near-drownings.....

Could anyone point me out what I :confound: am missing?

Jorgen

 

[The Iceni]

ScubaJorgen once bubbled...
Secundary drowning is caused by water inhaled during the first near-drowning. This water dissolves the lining of the lungs called surfactant. This surfactant stuff normally prevents the alveoli (cavities making up the lungs) from collapsing during the breathing process: it prevents the walls of the alveoli (and brancheoles?) from sticking together.

The secondary drowning somewhat contradicts the disolving-of-water-into-the-blood theory of Paul Thomas. If water gets dissolved into the blood, it is not supposed to dissolve surfactant. Furthermore, if osmosis is involved, you would expect fresh water to be dissolved into the blood, inflating bloodcells. You would expect secondary drowning with salt water near-drownings.....

Jorgen

Following some rapid reading to bring myself up to date;

The term secondary drowning is no longer considered useful. Rather the terms "salt water aspiration syndrome" and "adult respiratory distress syndrome" are now more commonly used.

Yes, ScubaJorgen, lung surfactant is completly destroyed by fresh water and damaged by salt water but this is only a part of the picture. The point I was making, which you appear not to have appreciated, is that fresh water near drowning is far more problematic than salt water near-drowing in terms of these conditions. The long term patholophysiology of salt water and fresh water lung damage is quite different and wholly due to osmosis.

Salt water is between 3 and four times more concentrated than body fluid, while body fluids are infinitely more conentrated than fresh water. Therfore the osmotic gradient in the two types of water are in opposite directions.

Salt water

A reasonably small amount of (concentrated) salt water causes a chemical or "aspiration" pneumonitis, with leaky inflammation of the airway linings. In addition salt water reduces the effectiveness of the lung surfactant but not so much as with fresh water. There is a net transfer of fluid from the blood and tissues INTO the alveoli producing a frothy, blood stained, pulmonary oedema. There is a net transfer of sodium, chloride and magnesium ions into the blood sufficient, in some cases, to cause major electrolyte distrurbances and a biochemically induced cardiac arrest. The airways become obstructed (similar to an asthma attack) and the alveoli are filled with oedema fluid.

Fresh water

Fresh water indeed destroys surfactant (Surfactant is "denatured" by water. It does not simply wash it away or dissolve it) and, yes, it causes the alveoli to collapse due to surface tension BUT THERE IS a mass transfer of water into the blood along the osmotic gradient and the lungs may appear quite dry in the victim of fresh-water drowning. This is not MY theory!

Thus it would appear that the victim of salt water immersion is at greater risk initially, while the survivor of fresh water near-drowning is at greater risk of ARDS and multisystem failure, including renal failure due to dilution haemolysis whereby the red cell pigments form "casts" in the the kidney.

Hypoxia is usually the cause of death, nevertheless.

Hypothermia, is protective against drowning and there are several documented cases of children, in particular, surviving long periods of cold water immersion.

From Edmunds, Lowry & Pennefather, Diving and Subaquatic Medicine.

:doctor:

 

[Scuba446]

I agree with the above....the glottis (sp?) goes into spasm and clenches down, and one can't move air (or water) in or out of the lungs. This is how the body protects one from actually swallowing a lung full or water - its the bodies defense mech that tries to prevent the entry of water (or any foreign object) into the lungs.

 

[The Iceni]

Yes indeed Scuba 446,

In fact the glottis is only one small part of the upper airway. Any toxic insult to the respiratory tree is likely to cause oedema and spasm in the entire larynx, not just at the level of the glottis. (By the way this is not a "reflex" any more than an acute asthma attack is a reflex)

This is why it is often so difficult to ventilate such patients artificially without endotracheal intubation.

The most common example of this is seen following smoke inhalation where the patient appears to be absolutely fine one minute but very rapidly deteriorates into complete, irreversible, obstructive respiratory arrest.

A very nasty time bomb, :boom:

All in all , it is best not to get any water at all into the respiratory tree, which is why I consider well designed bouyancy aids are a must. (All very well bringing your unconcious buddy to the surface but if you cannot keep his airway clear from the water you might just as well not have bothered.)

 

[Laurence Stein DDS]

Way back when I was a resident doing anesthesia, in the event of a laryngospasm, and without the aid of succinylcholine or curare, if you just waited for the patient to pass out from hypoxia, the spasm would usually stop and ventilation or intubation could continue.

Now I never had to treat a near drowning victim during that time but doesn't the spasm also abate and allow ventilation after unconsciousness or does the water in the lung cause a continued spasm?

Larry Stein

 

[The Iceni]

Laurence Stein DDS once bubbled...
...but doesn't the spasm also abate and allow ventilation after unconsciousness or does the water in the lung cause a continued spasm?

The spasm you encounted I believe was reflex and not due to a local "toxic" reaction but this is way beyond my current knowledge. I posed a similar question myself.;-

What happens to the glottis during a convulsion caused by CNS oxygen toxicity? In the tonic phase it is possible that the glottis could be in spasm leading to the risks of pulmonary barotrauma if the victim is brought to the surface during tonus but it seems likely to me that in the absence of water inhalation this will be short-lived. It would be interesting to learn the definitive answer.

One thing is for certain, an unconcious diver will have little chance of survival if he is not brought to the surface.