IS IT distressing to experience consciousness slipping away or something people can accept with equanimity? Are there any surprises in store as our existence draws to a close? These are questions that have plagued philosophers and scientists for centuries, and chances are you’ve pondered them too occasionally.

None of us can know the answers for sure until our own time comes, but the few individuals who have their brush with death interrupted by a last-minute reprieve can offer some intriguing insights. Advances in medical science, too, have led to a better understanding of what goes on as the body gives up the ghost.

Death comes in many guises, but one way or another it is usually a lack of oxygen to the brain that delivers the coup de grâce. Whether as a result of a heart attack, drowning or suffocation, for example, people ultimately die because their neurons are deprived of oxygen, leading to cessation of electrical activity in the brain – the modern definition of biological death.

If the flow of freshly oxygenated blood to the brain is stopped, through whatever mechanism, people tend to have about 10 seconds before losing consciousness. They may take many more minutes to die, though, with the exact mode of death affecting the subtleties of the final experience.

[su_heading size=”18″ margin=”10″]Drowning to Death[/su_heading]

Typically, when a victim realizes that they cannot keep their head above water they tend to panic, leading to the classic “surface struggle”. They gasp for air at the surface and hold their breath as they bob beneath. Struggling to breathe, they can’t call for help. Their bodies are upright, arms weakly grasping, as if trying to climb a non-existent ladder from the sea. Studies with New York lifeguards in the 1950s and 1960s found that this stage lasts just 20 to 60 seconds. When victims eventually submerge, they hold their breath for as long as possible, typically 30 to 90 seconds. After that, they inhale some water, splutter, cough and inhale more. Water in the lungs blocks gas exchange in delicate tissues, while inhaling water also triggers the airway to seal shut – a reflex called a laryngospasm. “There is a feeling of tearing and a burning sensation in the chest as water goes down into the airway. Then that sort of slips into a feeling of calmness and tranquility,” describing reports from survivors. That calmness represents the beginnings of the loss of consciousness from oxygen deprivation, which eventually results in the heart stopping and brain death.

[su_heading size=”18″]Heart attack[/su_heading]

heart-attack

 

The most common symptom is, of course, chest pain: a tightness, pressure or squeezing, often described as an “elephant on my chest”, which may be lasting or come and go. This is the heart muscle struggling and dying from oxygen deprivation. Pain can radiate to the jaw, throat, back, belly and arms. Other signs and symptoms include shortness of breath, nausea and cold sweats.

Most victims delay before seeking assistance, waiting an average of 2 to 6 hours. Women are the worst, probably because they are more likely to experience less well-known symptoms, such as breathlessness, back or jaw pain, or nausea, says JoAnn Manson, an epidemiologist at Harvard Medical School

Even small heart attacks can play havoc with the electrical impulses that control heart muscle contraction, effectively stopping it. In about 10 seconds the person loses consciousness, and minutes later they are dead.

[su_heading size=”18″]Burning to Death[/su_heading]

Long the fate of witches and heretics, burning to death is torture. Hot smoke and flames singe eyebrows and hair and burn the throat and airways, making it hard to breathe. Burns inflict immediate and intense pain through stimulation of the nociceptors – the pain nerves in the skin. To make matters worse, burns also trigger a rapid inflammatory response, which boosts sensitivity to pain in the injured tissues and surrounding areas. Most people who die in fires do not in fact die from burns. The most common cause of death is inhaling toxic gases – carbon monoxide, carbon dioxide and even hydrogen cyanide – together with the suffocating lack of oxygen. One study of fire deaths in Norway from 1996 found that almost 75 per cent of the 286 people autopsied had died from carbon monoxide poisoning. Depending on the size of the fire and how close you are to it, concentrations of carbon monoxide could start to cause headache and drowsiness in minutes, eventually leading to unconsciousness. According to the US National Fire Protection Association, 40 per cent of the victims of fatal home fires are knocked out by fumes before they can even wake up.

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