Re: Can humans breath oxygen enriched liquids underwater.

Very interesting question. Let's split the answer it in three parts:

First, before birth, when a fetus is in his mom's womb, he does not 
breathe. His lungs are not in function, and the alveoli (the billions of 
little spheras that receive air and exchange oxygen and carbon dioxid with 
the blood) are collapsed. At birth, various stimuli generate a sort of 
reflex wich makes respiration start. A good cry means that the newborn has 
initiated breathing the right way. Before delivery, the fetus gets its 
oxygen and glucose through umbilical blood flow. At birth, the circulatory 
pattern changes, and blood remains oxygenated through aerial respiration.

The second question is the tolerance of liquid respiration. I mean, is it 
possible to breathe water instead of air ?. Think to what happens when you 
let a drop of coffee or water go into your larynx and trachea instead of 
your oesophagus. You cough, and cough, until you have expelled the liquid. 
The inside of the trachea is very rich with nervous terminations wich, when 
irritated by a solid or liquid particle, generate a very strong cough 
reflex. It is a "survival reflex". In very particular settings, with strong 
behavorial training, you become able to breathe in a liquid environment 
(remember the rat in Abbys).

The last and most important question is, regardless of local tolerance of 
breathing in a liquid, the effectiveness of such a breathing. To reamin 
alive, you need an oxygen input through your lungs, i.e. you must get 
enough oxygen from your environment to your blood. Air contains 21% of 
oxygen, and the lungs are able to extract enough to fuel your brain, heart, 
muscles and so on through your blood flow. But, considering water, the 
amount of oxygen in water is far below the amount in air. Therefore, 
provided that you are trained to breathe in liquid, you will anyway die of 
anoxia, i.e. your lungs will not extract enough oxygen from water to keep 
your organism active (prevention of drowning lies in learning swimming, not 
training in order to tolerate water inhalation...)

In order to survive in a liquid environment, you need to be immerged in a 
very special liquid, whose oxygen concentration is rather high. Blood is 
this typical liquid...... In Abbys, the liquid was perfluorocarbon, a 
compound used as a blood substitute (artificial blood), wich allows a very 
high oxygen concentration when compared to water.

Experiments are ongoing in such a field. At present, rats are able to 
survive for a few minutes when immerged in a perfluorocarbon solution. I am 
not aware of such results in humans (maybe the Navy has secret 
experiments...)

Hope this helps

Luc

Luc A Ronchi, MD
Ped Anesth
Hopital de St Nazaire