When the cold strikes hard

Winter is one time of the year that most people in north India look forward to. But no one was prepared for the bitterly cold season that struck this year, leaving 500 dead (including around 10 in Delhi).

What few people know is that hypothermia is not a condition that strikes only those with inadequate shelter or people living in ice covered regions of the world. Hypothermia can strike even in moderate temperatures, when a sudden change in body temperature is accompanied by other health conditions such as winter dehydration.

"Our bodies have a low tolerance to any sudden change in temperature," says Dr M.P. Sharma, Head, Internal Medicine, Rockland Hospital.

Put simply, hypothermia is a medical emergency in which the body's core temperature, which controls the main organs of the body, drops below 35 degrees C. This occurs due to vasoconstriction i.e. the constriction of blood vessels due to overexposure to cold, which raises the blood pressure and leads to heart attack or stroke," says Dr Sharma.

Elderly people and others with existing health problems are vulnerable to it.

There are three phases of hypothermia. In the initial phase the body temperature drops to 32 degress C with symptoms such as violent shivering and confusion. In the second phase, the temperature further drops to 24 degress C with severe symptoms such as loss of consciousness, muscular rigidity and slurred speech. When the temperature falls below 24 degress C, this becomes a life-threatening condition.

Lowered defences
Our body's internal defences are always striving to maintain the body's core temperature. However, these defences can be weakened when the body loses heat faster than it produces it. This may happen when you don't wear clothes that protect the body from the cold, especially when it's windy outside. Wind can cause severe heat loss even when the temperature is moderate because air particles are put into motion, reducing the heat as they hit our bodies. That's why we feel colder while riding a bike than we do while walking.

Similarly, cold water can take away heat from the body much faster than air, which is why people in recreational sports like mountaineering die of hypothermia if their clothes get wet.

Other critical factors are a depressed metabolism, undernourishment, severe dehydration, and underlying health conditions such as diabetes, asthma, heart problems and a suppressed immune system.

Staying safe
Going for a walk or stepping out in the cold straight after getting out of bed in the morning is harmful for the health. It's better to acclimatise the body after leaving the bed for 20-30 minutes before going out.

Drinking plenty of water is also important in winter as we excrete plenty of body fluid and the dry heat from room heaters also causes dehydration "Since this thickens the blood, it's particularly important to have lots of fluids in winters," says Dr Ajay Rastogi, Consultant, Internal Medicine, Fortis Hospital, Noida.

Avoid going out immediately after having a bath or washing your hair.

Other health concerns
Extreme temperatures make life difficult for those suffer from various health problems and also people whose immune systems are suppressed. "Winter is the time when the metabolic rate slows down. That's the reason why people have frequent flu, colds, bronchitis, respiratory infections, high blood pressure and joint pains," says Dr Balbir Singh, Senior consultant, Cardiology, Medanta-The Medicity.

It's commonly believed that low temperatures also cause high blood pressure and affect the cardiac health, particularly of those already suffering from heart problems. In cold weather our blood vessels constrict, preventing blood from flowing smoothly. Consequently, the heart has to work harder to pump blood through narrower vessels, which leads to high blood pressure. Also, there is more strain on the heart when it has to work harder.