Carrying excess weight may mimic symptoms of asthma

While many people experience wheezing and breathlessness, "true asthma," Dr. King notes, occurs in airways that are hyperresponsive -- when the airways suddenly narrow in response to such stimuli as allergens, cold air, salt water, or excess laughing. "Wheezing and breathlessness are subjective. But we have objective tests that check for hyperresponsiveness."

• Being obese can compress the chest and lungs causing breathlessness and wheezing that may be misdiagnosed as asthma, say Australian researchers.
• Their study, to be released in the May issue of the European Respiratory Journal, found the extra weight obese people carry reduces their lung volume and causes their airways to narrow.
• Respiratory physician Dr Greg King from the Woolcock Institute of Medical Research in Sydney says the impact of excess weight on lung performance is especially strong in obese men.
• "This may be because men and women carry excess weight differently with males tending to carry it around the chest," says King, who led the research.
• Hyperresponsiveness is when the airways narrow suddenly in response to a stimulus such as exposure to allergens, cold air, salt water or even excessive laughing, he says.
• King and his team measured the lung capacity, airway size and flow of air in 322 men and women aged 28 to 30 from the Belmont region of New South Wales.
• People in the study completed questionnaires about respiratory symptoms, treatments and smoking history, and had a skin-prick test for eight common allergens.
• King says the findings affect how doctors diagnose and treat asthma-like symptoms in overweight patients, especially with an increase in obesity in western society.
• "Sometimes the breathlessness and wheezing is due to true asthma but our results suggest the symptoms may be due to the extra weight and not airway hyperresponsiveness," explains King.
• "If the symptoms are due to the obesity, drug treatment for asthma would be inappropriate and unlikely to work while the most appropriate treatment would be weight loss."
• The researchers say their results may not apply to older obese people with asthma-like symptoms, where lung elasticity may play a larger role in determining how airways function.