Kathmandu:

Public attention in the developed world has recently focused on asthma because of its rapidly increasing prevalence, affecting up to one in four urban children.

Asthma is a chronic disease of the respiratory system in which the airway (the tubes that carry air in and out of your lungs) occasionally constricts, becomes inflamed, and is lined with excessive amounts of mucus, often in response to one or more triggers. These episodes may be triggered by such things as exposure to an environmental stimulant (or allergen), cold air, exercise or exertion, or emotional stress. When the airways react, they get narrower, and less air flows through to your lung tissue. This causes symptoms like wheezing (a whistling sound when you breathe), coughing, chest tightness, and trouble while breathing, especially at night and in the early morning.

Asthma attacks are not all the same—some are worse than others. In a severe asthma attack, the airways can close so much that not enough oxygen gets to vital organs. This condition is a medical emergency. People can die from severe asthma attacks.

Your red blood cells must carry sufficient oxygen through your arteries to all of your internal organs to keep you alive. Normally, when red blood cells pass through the lungs, 95%-100% of them are loaded, or “saturated,” with oxygen to carry. If you have asthma, lung disease or other types of medical conditions, fewer of your red blood cells may be carrying their usual load of oxygen, and your oxygen saturation might be lower than 95%. Technology, today, allows us to estimate oxygen saturation easily, economically and painlessly. A variety of products are available in the market today, which can be selected based on their functionality, from fingertip oximetry to wireless ones. For example, in fingertip oximetry, a clip that fits on your fingertip shines a light through one side of your finger; a detector measures the light that comes through the other side. This machine can make a good guess about your oxygen saturation because blood cells that are saturated with oxygen absorb and reflect light differently than those that are not. Blood cells are a bright red when they are loaded with oxygen, and they change to a bluish color when they are no longer carrying a full load (this is why arteries are red and veins are blue in color).