[PSUBS-MAILIST] Fluid Breathing - "The Abyss"

["Steven Mills" <barycenter@earthlink.net>]

Here's a research summary on the film "The Abyss" and
liquid breathing. [ No author name given. ]

--Steve


http://www.scienceweb.org/movies/abyss1.htm

http://www.scienceweb.org/movies/abyss.html



The Abyss
Fluid Breathing
Miscellaneous Notes 
  
Some Interesting Things I Learned During My Research  

In very early tests, subjects were placed in oxygenated water. The subjects could survive hours if they were placed in oxygenated fluorocarbon, but only minutes if air-saturated water was used. 

Some things that could cause carbon dioxide buildup: slow diffusion of gases in water and low solubility of carbon dioxide in water (in the early '60s tests), and in particular the mechanical factors which limit expiration flow rate (airway size). 

A given volume of oxygen-saturated fluorocarbon contains 3 times as much oxygen as the same volume of air or whole blood. 

There was some hemorrhaging in the lungs of the dogs used in the early '90s tests, but pressure inside the lungs was not high enough to cause damage. 

In the mid '60s, goldfish were kept alive in a solution of silicone oil for several weeks. 

Curiously, improvement of gas exchange (lung efficiency) was noted in the dogs used in the tests in the early '90s after the perfluorocarbon was drained from their lungs. 

Perflubron can also be used as a blood substitute (given the trade name Oxygent). 
While not being able to perform all the tasks of blood (it won't clot, for example), but can be used as a "temporary oxygen delivery agent." 
Perflubron is biologically and chemically inert. 
Oxygent dissolves oxygen and carbon dioxide, transporting oxygen through the bloodstream and exchanging it for carbon dioxide at the tissue level, just like red blood cells, only faster. 
When the Oxygent particles return to the lungs, the carbon dioxide is expired and it takes on new oxygen. 
This type of procedure (blood substitution) was first tested in the "bloodless rats" of Dr. R. P. Geyer in 1968. 
It is used during surgery at the point where the physician would normally give blood.

Some whales can dive to over 900m. They have lungs, so you'd think it would be impossible, but in fact, the whales' lungs actually collapse during their descent. With a small lung volume to begin with, there is little nitrogen in the system at the start of the dive, hence little danger of nitrogen bubbles forming in the blood. 

Record depth for breath-held diving: 351 ft, Angela Bandini of Italy (she was underwater for 2m 46s). 

Record scuba dive: 437 ft, John Gruener & Neal Watson of USA (October 14/68) 

Record dive using gas mixtures: a simulated dive to 2300 ft during a 43 day dive (Theo Marrostomos, Nov 20/92); he was breathing "hydreliox" (hydrogen, oxygen, helium) 

According to the movie: deepest suit dive is 4800ft (Bud goes to 8900ft+, that's equivalent to about 300 atmospheres of pressure! Tests with mice have been done at pressures of up to 8000 feet) 

Any fluid used in fluid breathing must be nontoxic, and nonsoluble in water or in fats (so it can't get into the tissues). 

A few of the mice in the early tests died from exhaustion from the increased work of breathing, as well as hypothermia. 

Normal lung tissue is very light; injured lung tissue is dense with fluid and the weight of this fluid-filled tissue exceeds the ability of the gas pressure and the mechanical strength of the small air sacs (alveoli) to resist it, making the alveoli collapse. 

With a damaged lung, most of the blood leaving the heart doesn't get oxygenated (no gas exchange possible in the lung) and gets distributed without removal of carbon dioxide. 

Even at a depth of 60cm, the pressure differential acting on the lungs makes breathing difficult (as well as subjecting the circulatory system to an enormous amount of stress) 

Scuba stands for "Self Contained Underwater Breathing Apparatus." 

In scuba diving, the regulator supplies air to the diver at whatever pressure is exerted by the water on his body, therefore he can breathe properly. 

For every increased depth of 10m, 1 atmosphere of pressure is added. At depth of 30m, therefore, the pressure would be 3 times what it is on the surface (that depth is the limit for scuba diving). 

Pure oxygen can be breathed safely only to a depth of about 7m. As the pressure of the oxygen increases, so does its toxic effects (it can cause physical changes in the lung, as well as secondary effects in the liver and brain; acute oxygen poisoning can lead to dangerous convulsions). 

Nitrogen narcosis and decompression sickness are a result of nitrogen dissolving in the tissues. In mild cases, the only noticeable effects are joint pains and some itching. In severe cases, however, gas embolization (the prescence of air bubbles in the bloodstream) and death can occur. For that reason, divers must ascend gradually (for example, a dive to 90m will require that the diver take 5-6 hours to ascend to the surface). 

Decompression sickness results after ascent to a lesser pressure ...dissolved gas "bubbles" out of solution (like opening a coke bottle) and creates the problems. 

Nitrogen narcosis occurs at depth .. it is believed that nitrogen dissolves in fatty tissue of nerve and disrupts nerve conduction ...this can lead to euphoria (rapture of the deep) in warm clear water, but can lead to dread and uncertainty in unclear, cold water. 

Mixed gas diving (and other gases than helium can used) replaces nitrogen to prevent narcosis ... Helium is used because it is NOT narcotic ...so; divers can think clearly and act appropriately. 

Another problem during too rapid ascent: as the pressure on the chest diminishes, gas in the lungs expands, leading to rupture of lung alveoli. For that reason, it is vitally important that the airway is kept open during ascent (in other words, don't hold your breath on the way up). 

The study mentioned in the "Medical Uses" section involved infants born between 24-34 weeks of gestation. 

Of the infants that died during the study, three died from acute lung disease, one died from bronchopulmonary dysplasia, and two complications of prematurity unrelated to their respiratory system. 

A good reference for liquid breathing is: Liquid Breathing & Artificial Gills by J. Kylstra, a chapter in: Bennett & Elliot (eds) (1982), PHYSIOLOGY AND MEDICINE OF DIVING, published by Best Publications. Special thanks to Larry "Harris" Taylor, Ph.D., of the University of Michigan for putting me on to this, and also for correcting a few misconceptions I had about nitrogen narcosis, mixed gas diving, and the effects of depth.