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Not Ranked : +0 / -0 0 score Re: Clinical Death As I deal with death in my line of work sometimes, I might answer this question for you.
As to the first question: What does it mean to be clinically dead.
You are clinically dead when the heart and respiration stops. All hope is not out, because in a certain timeframe after cardiac arrest, it is in many cases possible to jumpstart the heart again, and get respiration going by applying first-aid. Even if the first aid does not succeed in getting the heart and respiration started again, it may give the patient enough oxygen so that the brain does not die, and more advanced methods of starting the heart can be applied.
Also, cold temperatures slows the time it takes for cells to die, so people that drown in cold water often can be revived for a longer time period than those that drown in warmer water. Persons with low body mass cool quicker than persons with high body mass, and this is one of the reasons why kids have a greater chance of being revived after drowning and being submerged for a long time in cold water than adults.
It may help to understand the various versions of being dead by understanding that death is not an event, but a process.
If we take the case of cardiac arrest, the first thing that happens after the heart stops to beat, is that blood is no longer pumped through the body. Cells still have oxygen present that they can use, and the blood bathing the cells will also contain some oxygen. This oxygen gets rapidly depleted, and cells starts to work anaerobically. Some cells are specialized in working under anaerobic conditions, such as the muscle cells. It takes a long time before a muscle cell die because of that. Other cells, such as brain cells, do not deal very well with anoxia, and because of this, brain cells die after just a few minutes without oxygen supply. Cold temperature may increase the time it takes for the brain cells to die, because chemical reactions occur slower rates at lower temperatures.
This is the first part of death, and it happens during the first 5 minutes after cardiac arrest (may be longer in cold water). Everything but the brain damage is reversible during this stage. And even with some brain damage, it is possible to train other undamaged parts of the brain to do some of the functions that the old damaged parts did before. But in general, the longer it takes before basic first aid is applied, the greater the chance of permanent brain damage or even unsuccessful revival.
when all the parts of the brain, including the brain-stem, are non-functional, the person goes from clinically dead to irreversibly dead. Even at this point, many other cells in the body is still alive. One of the longest lived cell types are those of the cornea, as these get oxygen from the air, not from blood. I can probably give a long speech about the later changes after death, but I think I will stop here.
---------------- Morten S
- Time is fun when we're having flies. - Kermit the frog Let's BOINC for Hypography! || MyBoincStats || Hypography BoincStats
Last edited by MortenS; 07-31-2005 at 09:13 AM..
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