Asphyxia / Hypoxia

[TigerShark]

Hello everybody,

from my understanding, Asphyxia is lacking of oxygen....is it the same then as Hypoxia?

Is there anybody who can / willing to explain more on this ?

Thanks very much....pls correct me if i'm wrong in any way.

Thanks!!

 

[norcaldiver]

National Institute of Neurological Disorders and Stroke says:
Specifically, anoxia is a condition in which there is an absence of oxygen supply to an organ's tissues although there is adequate blood flow to the tissue. Hypoxia is a condition in which there is a decrease of oxygen to the tissue in spite of adequate blood flow to the tissue. Anoxia and hypoxia, however, are often used interchangeably—without regard to their specific meanings—to describe a condition that occurs in an organ when there is a diminished supply of oxygen to the organ's tissues. Anoxia and hypoxia may be caused by a number of events, such as heart attack, severe asthma, smoke or carbon monoxide inhalation, high altitude exposure, strangulation, anesthetic accidents, or poisoning. In severe cases of anoxia and hypoxia, from any cause, the patient is often stuperous or comatose (in a state of unconsciousness) for periods ranging from hours to days, weeks, or months. Seizures, myoclonic jerks (muscle spasms or twitches), and neck stiffness may occur

The encyclopedia of diving has a really good explaination in relation to breath-hold diving and shallow water blackout.
It goes something like this:
You take a breath and dive down. The increased preasure at depth makes you body use up the o2 in your lungs faster than at the surface. As you come up, the pp is reduced and now there's a very low amount of o2 that's getting into your bloodstream. If it's TOO low, you become hypoxic, way low and not enough o2 is getting to your brain and "out you go".

I'm not a Doctor, nor do I play one on TV.

 

[BillP]

Howdy TigerShark:

Hypoxia refers to a deficiency of the amount of oxygen delivered to the tissues. It is possible to be mildly hypoxic. If you're not too hypoxic, you can be hypoxic and still walk down the street, although likely with some difficulty. (As norcaldiver said, anoxia is the absence of oxygen, but you didn't ask about that.)

Asphyxia refers to hypoxia of sufficient degree to cause unconsciousness, and eventually, death. Hypoxia can be bad enough to cause asphyxia, but it doesn't have to be. Anoxia would certainly cause asphyxia if if lasted long enough.

HTH,

Bill

 

[The Iceni]

Hi Tigershark,

I last read a medical encyclopaedia some years ago so my understanding may be out of date.

Hypo. . means lower than, hyper. . means higher than (normal).

A. . . or An . . . means without, or the abscence of. (from classical Greek?)

Sphyxia. I suppose must mean respiration but will check.

In physiological terms, I believe asphyxia implies hypoxia due to respiratory causes, such as asphyxiation with a pillow, by strangulation or even by carbon monoxide poisoning. It is not limited to oxygen. CO2 retention could be considered asphyxia. Silo workers can becomne asphyxiated in a hypoxic environment.

Hypoxia is more specific and relates to low levels of oxygen either generally or at the tissue level, from whatever cause (eg. a blood clot or bubble in the artery supplying an organ will cause localised tissue hypoxia.)

Anoxia literally means a complete absence of oxygen - the ultimate hypoxia

In diving, an hypoxic mix will contain too little oxygen to support life at surface pressure, which is generally accepted as about 10% oxygen in the breathing medium = 0.1 bar.

Needless to say there is no such thing as an anoxic mix, unless you connect your regulator to the argon bottle, or forget to turn on the oxygen of your rebreather;- as the oxygen in the loop is used up (dilution) hypoxia and unconciousness results.

Remember I'm a Brit, Bill. American definitions may differ.

Hope this is of interest.

 

[BillP]

Dr Paul Thomas once bubbled...


Remember I'm a Brit, Bill. American definitions may differ.

We don't really speak English on this side of The Pond, do we?

The word asphyxia comes from the Greek meaning absence of a heartbeat. Over here it has come to specifically mean absence of a heartbeat (death) due to insufficient oxygen (because of suffocation, strangulation, drowning, toxic gases that interfere with oxygen transport, etc.)

Sometimes that definition is expanded to include situations where people are rendered unconscious due to levels of oxygen low enough to cause eventual death, yet they are rescued/resuscitated in time to prevent absence of a heartbeat.

HTH,

Bill

 

[The Iceni]

BillP once bubbled...
The word asphyxia . . . situations where people are rendered unconscious due to levels of oxygen low enough to cause eventual death, yet they are rescued/resuscitated in time to prevent absence of a heartbeat.

I'll accept that.

 

[TigerShark]

BillP once bubbled...
Howdy TigerShark:

Hypoxia refers to a deficiency of the amount of oxygen delivered to the tissues. It is possible to be mildly hypoxic. If you're not too hypoxic, you can be hypoxic and still walk down the street, although likely with some difficulty. (As norcaldiver said, anoxia is the absence of oxygen, but you didn't ask about that.)

Asphyxia refers to hypoxia of sufficient degree to cause unconsciousness, and eventually, death. Hypoxia can be bad enough to cause asphyxia, but it doesn't have to be. Anoxia would certainly cause asphyxia if if lasted long enough.

HTH,

Bill

Hello everybody,

thanks for your explaination on this.

Hi Bill,

so i can say that Asphyxia is most likely to occur after hypoxia and anoxia according to your explainations,provided i interpret correctly.

Thanks!

 

[BillP]

TigerShark asked...

so i can say that Asphyxia is most likely to occur after hypoxia and anoxia according to your explainations,provided i interpret correctly.

Hmmm... my answer might need some clarification and your statement maybe requires some refinement. If you had said "sufficient hypoxia or anoxia" it might have been better. The way it's written now, your statement might be interpreted by some people to mean that any hypoxia will lead to asphyxia, or that anoxia is required in order to asphyxiate. Not true.

Another way of making your statement might be, "Asphyxia will occur if there is inadequate oxygen delivery to the tissues to support life".

Sitting around here at rest at the computer at ~sea level we are breathing ~21% oxygen and barring medical conditions we are not hypoxic (ie we do not have insufficient oxygen delivery to our tissues).

If we were to go on a mask and start breathing a hypoxic mix with 16% oxygen (but remain at rest) our tissues would become hypoxic and we would have mild symptoms of hypoxia. We would not asphyxiate.

If we were to begin breathing a mix with 12% oxygen we would develop severe sypmtoms and signs of hypoxia, but we would likely not asphyxiate.

If we were to breathe a mix with 10% oxygen we would probably lose consciousness, perhaps suffer irreparable harm if we breathe the mix long enough, and after a period time perhaps in some cases even asphyxiate (die due lack of oxygen).

If we were to breathe a hypoxic mix with 4% oxygen for more than a brief period of time, we would asphyxiate.

If we were to breathe an anoxic mix (no oxygen- 0%) we would die of asphyxia rather quickly.

One can live just fine with mild hypoxia. People with emphysema and other medical conditions walk around the mall hypoxic all the time without asphyxiating.

But, if one is hypoxic enough, one will asphyxiate.

Asphyxia, by definition, always involves inadequate oxygen delivery to the tissues- ie hypoxia- but it does not require anoxia.

Anoxia (total absence of oxygen) will inevitably lead to asphyxia, but it is not required in order to asphyxiate. One can asphyxiate even with some oxygen present.

One can asphyxiate in the presence of normal levels of oxygen in the breathing mix. For example, if you introduce a poison gas like carbon monoxide into your breathing mix, you can asphyxiate because the gas interferes with the blood's ability to transport oxygen to the tissues. You can asphyxiate despite breathing 21% (or even higher) O2.

Clearer?

 

[TigerShark]

Crystal.

Thanks!