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What in the world is…cold water shock?


You may have heard about the San Jose Earthquakes player that recently emerged from a coma after suffering what is believed to be cold water shock earlier in July. Matheus Silva, a Brazilian midfielder on loan with the Earthquakes’ affiliate Reno 1868 FC, was pulled from the water by teammates and bystanders after appearing to struggle under the water. Despite being a decent swimmer, Silva fell victim to the icy syndrome that can happen to anyone, regardless of skill.

But what is it?

According to Roy Schutzengel, M.D. at Adventist Health Physician Services in Roseville, California, cold water shock refers to a reflex, instant reaction to sudden submersion in cold water. He explains that there can be cardiac and respiratory “shut down” responses.  Alternatively, the cardiac response may also be a “fight or flight” type, with increased cardiac output—shown by a sudden, increased heart rate that can also potentially cause a sudden jump in blood pressure—which in the elderly or infirm can lead to strokes or heart attacks.

But wait, doesn’t that sound like hypothermia? Not exactly.

The difference between cold-water shock and hypothermia is, essentially, all about time. Dr. Schutzengel explains, “Hypothermia is when the body temperature drops significantly below normal temperature with prolonged exposure to cold. This causes a slowing of body function. The heart rate, respiratory rate and blood pressure drops. So the end effect (loss of function) is the same but the mechanism is different.”

Especially on a hot day, it’s easy to think we can take a quick swim in cold water to cool down—but even the best swimmers (or athletes!) can underestimate the effect that cold water can have on the muscles.

Dr. Schutzengel says that these syndromes are not common, but the good news is that they are avoidable. “The most common scenario is someone falls overboard on a boat, and because of the sudden cold they could struggle to breathe and drown—even though they are good swimmers. Always wear a life jacket when on a boat, particularly when the water is known to be cold early in the boating season. And when swimming in cold water, wear a wet suit and limit the amount of time spent in the water.”

So if you’re planning to spend a day cooling off on the water, be sure to take a few safety precautions. Make a life jacket your best accessory!


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