With summer water sports and recreation, hypothermiais a constant risk. However, hypothermia prevention in open water swimming in the Lower Mainland has improved since the introduction of guidelines by the Vancouver Lifeguard Society, says Ron Straight, a paramedic and lifeguard, who teaches first aid courses for SportMedBC. And Dale Miller of the Canadian Lifesaving Society says that his organization is seeing fewer drownings every year. When drowning does occur, "the problem is that most people have no intention of going into the water so they don't prepare properly," he says.

Ron Straight has often witnessed hypothermia at Vancouver's popular New Year's Day polar bear swim. When hypothermia occurs, it progresses like "clockwork", beginning with shivering, followed by slurred speech and uncoordinated movements to an unresponsive state if not quickly treated. For the last two years, lifeguards at the event have used a "heat treat" system to warm the person up from the inside out rather than from their extremities. With this "passive rewarming" method, warm oxygen is given through a mask when the person has past the shivering stage. A hot water bottle may also be placed in the axilla and on the person's chest and they are covered with a blanket. The treatment is carried out in the heated lifeguard room at the beach.

Ron Straight has also worked at the open water swim from Lighthouse Park to Kitsilano Beach, a route that he says can be adversely affected by southeasterly winds, forcing swimmers to change course. He says the following factors help make the crossing safer:

• Escort boats: Every swimmer has an individual escort boat so that they can be quickly plucked from the water if necessary.
• Wetsuits: The thickness of the wetsuit should be relative to the coldness of the water. Thinner wetsuits will compromise cold protection in favour of increased freedom of movement.
• Head covering: Like the wetsuit, the thickness of the hat should be selected according to the water temperature. Some swimmers like neoprene swim caps but silicone may offer better head protection.
• Course markers: Highly visible course markers are important to assist swimmers to complete the swim in the most efficient manner. Straying off course will result in the swimmer spending more time in the water, increasing their potential to become hypothermic.
• Well energized swimmers: Swimmers need to be provided with fluid replacement during the swim by their escort boat crew.

Well-trained lifeguards can distinguish between non-swimmers and tired swimmers, says Ron Straight. A tired swimmer is more likely to wave their arm for help than a non-swimmer who may be taking in water and coughing when they start experiencing problems in the water. Someone undergoing serious signs or symptoms, such as a cardiac arrest, would present a more passive picture, becoming flaccid and non-responsive, he explains. Lifeguards need to recognize this person's presentation in the water too.

Drowning occurs in seconds following water aspiration, as the lung's alveolar tissue reacts by swelling causing pulmonary edema, which prevents air exchange and normal breathing.

Secondary drowning refers to cases where people are rescued from the water but continue to cough up aspirated water. These people need careful monitoring of their vital signs over the next few days. They will be given oxygen and their lung function assessed, if crackles are heard in the lungs, they are hospitalized.
 

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