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Recent news of a Singaporean who died in Hong Kong puts the spotlight on how cold weather may trigger bodily changes that can kill. JOAN CHEW reports
 Cold Weather can Kill You
It can affect your body in several ways which raise your risk of a heart attack. Especially if you are already at a higher risk because of existing heart problems, hypertension and high cholesterol. In rare cases, low surrounding temperatures can also affect the core body temperature and result in hypothermia, a potentially fatal condition that disrupts the body’s normal functions and metabolism. So those travelling to temperate countries experiencing the winter season now, like China and the United States, should prepare appropriate winter wear and eat and rest well to avoid triggering a heart attack or an episode of hypothermia, doctors said.
Be Warned
Two weeks ago, a Singaporean businessman, Mr Derek Tham Siang Aik, 51, died after collapsing at a wargames training centre in Yuen Long, Hong Kong. He was believed to have had high cholesterol and high blood pressure. Doctors here said that he died after his heart suddenly stopped beating probably due to a heart attack or undiagnosed heart diseases. Although the results of his autopsy are not out yet, Hong Kong newspaper reports said that the 20 deg C temperature difference between Singapore and Hong Kong could have been a factor in his collapse. Hong Kong newspaper Apple Daily reported that the temperature in Yuen Long was around 15 deg C at the time of the incident.
The Cold Weather Trigger
Lower temperatures do trigger heart attacks, a study published in the British Medical Journal in August this year found. Based on hospital records in Britain of more than 84,000 people who had suffered heart attacks, the researchers calculated that for every 1 deg C drop in the outdoor temperature on a given day, the incidence of heart attacks would rise by 2 per cent over the next month. In Britain, where about 146,000 heart attacks occur in a year, this translates to an additional 200 heart attacks each day. Neither flu nor air pollution could explain this association, said the researchers from the London School of Hygiene and Tropical Medicine.
- Arteries can become gradually blocked over time by fatty deposits that harden into a plaque on their walls, in a condition called coronary heart disease.
- A heart attack occurs when the surface of a plaque tears, forming a blood clot which can completely block the flow of blood in the artery, said a cardiothoracic and vascular surgeon in Singapore.
- The heart develops an abnormal rhythm called arrhythmia and suddenly stops beating.
Changes may Increase Risk
People have no symptoms if an artery is blocked by less than 70 per cent, but may experience chest discomfort, pallor or a raised heart rate if the blockage is more severe. The risk of plaque rupture is affected not by the initial degree of blockage in the artery, but by the stability of the plaque. Physiological changes brought on by the cold weather may increase the risk of the plaque rupturing, leading to a heart attack. Such changes include:
- When the surrounding temperature is low, blood vessels in the skin constrict to reduce the amount of heat that is lost from the body, explained Dr Aaron Wong, senior consultant at the department of cardiology at the National Heart Centre, Singapore. But this also narrows the blood vessels, making it harder for blood to circulate in the body and placing more stress on the heart.
- Changes in hormone secretion during cold weather cause an increase in blood pressure, Dr Wong said.
- The blood also becomes more viscous, or sticky, raising the likelihood of clots forming in the arteries, a precursor to heart attacks, he said.
- Lastly, the cold causes an involuntary reaction of shivering to keep warm, which consumes energy and increases one’s heart rate. Dr Wong said: “These changes, in addition to heavy exertion, may trigger a heart attack during cold weather.”
Hypothermia in Winter
Some people can also develop hypothermia when their core body temperature drops below 35 deg C and the body’s functions and metabolism are disrupted. It is usually caused by unprepared exposure to cold weather, such as falling into an icy, cold lake, or poor heating and inappropriate clothes during winter. Mild hypothermia of between 32 and 35 deg C will cause symptoms such as lethargy, apathy and confusion, while severe cases of below 28 deg C lead to delirium and eventually coma and death, Dr Wong said.
During severe hypothermia, people can also develop arrhythmia that can cause the heart to stop, he added. But he noted that it is unusual to get hypothermia in this day and age, although very young children and elderly people may be at risk as they are less able to generate heat and may not know how to keep themselves warm.
Stress of Travelling
The changes in one’s diet and biological rhythm due to time differences, coupled with disruptions to exercise routines, put a strain on the body system too. The key to being safe while travelling overseas is to be aware of any medical condition that you may have and to stick to the medication prescribed for it. Guard against extreme changes in temperature by putting on appropriate thermal wear. |
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