Approximately 80 to 90 percent of COPD cases are caused by smoking. A smoker is 10 times more likely than a nonsmoker to die of COPD. The causes of COPD are not fully understood. It is generally agreed that the most important cause of chronic bronchitis and emphysema is cigarette smoking. Causes such as air pollution and occupational exposures may play a role, especially when combined with cigarette smoking. Heredity also plays a contributing role in some patient's emphysema.
People with COPD are not able to use their breathing muscles effectively. The principle reason for this ineffectiveness is that the diaphragm, the main breathing muscle is unable to work properly. Tar from cigarettes coats the inside of the lungs weighing them down and preventing the natural recoil action of exhaling, which causes overinflation of the lungs. A onepack- a-day smoker puts one quart of tar into their lungs each year. This overinflation of the lungs pushes the diaphragm down and thereby prevents it from contracting effectively. The result is increased work of breathing and therefore, higher energy expenditure.
|
|
