Blood Pressure Drop

The complex phenomenon of circumrescue collapse is not well understood. It can occur just before rescue, during rescue – as the victim is removed from the water - and after rescue, when the person is out of the water.  It can result in loss of consciousness and also heart failure.  

 

It's not uncommon for a victim who has been in cold water for a long time to lose consciousness when they're removed from the water- particularly when vertically hoisted up the side of a tall ship or into a hovering helicopter.  In that situation, the cause is likely an abrupt drop in blood pressure. When water pressure on the body is lost, the resulting hypotension is an obvious suspect. 

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Exercise Caution

Consequently, rescue personnel should be careful about removing a victim from the water in a vertical position, particularly if hoisting into a helicopter.  The safer position for the victim is horizontal, so a basket hoist or horizontal sling is preferred to using a strop.  When pulling a victim up into a smaller boat, have them lie down as soon as possible.