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Old 06-09-2011
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Question Drowning in Freshwater

what happens as the most common?



Water intoxication?
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I think ARDS
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Old 06-09-2011
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Default Cardiac arrest in drowning! Sooner in fresh water!

Cardiac arrest within minutes! Sooner with fresh water drowning! See below! Underlying mechanism is interesting-different in fresh and sea water!

A lack of oxygen or chemical changes in the lungs may cause the heart to stop beating; this cardiac arrest stops the flow of blood and thus stops the transport of oxygen to the brain. Cardiac arrest used to be the traditional point of death but at this point there is still a chance of recovery. The brain will die after approximately six minutes without oxygen but special conditions may prolong this (see 'cold water drowning' below).

As well as the direct effect of oxygen deprivation, there are also dangerous effects on blood chemistry if water is taken into the
lungs. The mechanism for this is different for fresh and seawater.
  • Freshwater taken into the lungs will be pulled into the pulmonary circulation by osmosis. The dilution of blood leads to hemolysis (bursting of red blood cells). The resulting elevation of plasma K+ (potassium) level and depression of Na+ (sodium) level alter the electrical activity of the heart often causing ventricular fibrillation. In animal experiments this effect was shown to be capable of causing cardiac arrest in 2 to 3 minutes. Acute renal failure can also result from hemoglobin from the burst blood cells accumulating in the kidneys, and cardiac arrest can also result if cold freshwater taken into the bloodstream sufficiently cools the heart.
  • Sea water is hypertonic to blood (more salty). It poses the opposite danger. Osmosis will instead pull water from the bloodstream into the lungs, thickening the blood. In animal experiments the thicker blood requires more work from the heart leading to cardiac arrest in 8 to 10 minutes.
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