Naviglio Grande Canal in Milan, Italian. The five  boys dive off a bridge into the murky cool water.  

They pop up laughing and splashing  each other. But something's wrong.  

Michael's friends realize that he's  missing--he never returned to the surface. 

They quickly dive back down and find Michael.  He's about 6 feet (1.8 meters) under water,  

caught in the grip of a strong current.  Worse yet, his foot is stuck in a  

barricade of wooden poles used to guide boats. Michael's friends frantically try to free him.  

The commotion attracts the attention of a  man jogging by. He strips down and dives  

in to help. But Michael's foot won't come loose. Someone calls the emergency services. Firefighters  

quickly arrive and send divers down to free  Michael. Finally, about 42 minutes after he  

first dived, rescuers return Michael to the  surface. He's limp, cold, and unconscious. 

They lay Michael on the bank and check for  signs of life. Surprisingly, they detect a faint  

heartbeat. The rescuers do chest compressions  and attempt to resuscitate him on the spot,  

but to no avail. Michael is rushed  to a local hospital and hospitalized  

in the cardiac surgery intensive care unit. He spends the next month in a coma attached  

to machines which breathe on his behalf and  keep his heart pumping. When Michael awakes,  

he's alert and able to recognize his parents.  He even asks about his favorite soccer team.  

Miraculously, he has no brain damage  and is able to make a complete recovery. 

How did someone survive underwater for nearly  an hour without air? Although Michael's 42  

minute ordeal is the longest we were able to  find, there have been a few other accounts of  

people stuck underwater for 15 or 20 minutes who  survived. Many were able to make a full recovery. 

Generally, brain damage begins after  about 1-2 minutes without oxygen.  

At 4-6 minutes the occurring brain  damage is severe and likely permanent.  

Around 10 minutes without oxygen death occurs. While doctors cannot fully explain Michael's  

miraculous survival, there are two main  theories of why he was able to survive.  

First, the bradycardic response which  is part of the mammalian diving reflex.  

This physiological response is the same  reflex that babies up to 6 months old have  

when their heads are submerged in water. They hold  their breath, their hearts slow down and blood is  

shifted away from extremities and less essential  organs to conserve oxygen for their brains and  

hearts. This reflex also protects babies from  getting milk in their lungs while nursing. 

Around 6 months in age, babies begin to  gradually lose the reflex. However adults  

often retain vestiges of it. If you dunk your face  in cold water, you'll gasp and hold your breath.  

Unfortunately, the bradycardic response is hard  to study in humans, especially adults, as it would  

involve recreating near-drowning experiences. The second theory as to how Michael could have  

survived so long underwater is the selective brain  cooling hypothesis. Studies have determined that  

the quicker the brain cools, the more likely  it is to survive. When immersed in water,  

the human body retains carbon dioxide as a  result of not breathing, which causes blood  

vessels in the brain to dilate to allow increased  blood flow so the brain can receive more oxygen.  

This function is called hypercapnic  vasodilation. When submerged in cool water,  

the blood in the extremities begins to cool and as  hypercapnic vasodilation happens, the cool blood  

flows to the brain. As a result, the brain cools  faster. The colder the water, the more quickly  

cool blood flows to the brain and the longer  the brain may be sustained. The water Michael  

dived into was a chilly 59 degrees F (15 C). It's been noted that most of the survivors of near  

drownings with minimal effects tend to be young  and the water they've been submerged in is cold,  

suggesting that both theories play a role  with the brain cooling hypothesis being aided  

by the bradycardic response. Michael's near  drowning fits this profile. Also essential to  

Michael's survival was the emergency CPR  that was administered to him immediately  

after he had been pulled from the river. And now that you've reached the end of our video,  

why not keep the watch party going?! Ever wonder how you would react if  

you were trapped in a sinking car? Click  here for a life hack on how to survive:

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