The Place Of The Spirometer In Diagnosing Lung Conditions

By Jaclyn Hurley


One of the most common tests for measuring lung function is the use of a spirometer. This is a device that measures the speed and volume of air inspired and expired by a person's lungs. Spirometry is used to assess conditions such as chronic obstructive pulmonary disorder (COPD), asthma, cystic fibrosis and pulmonary fibrosis. It is able to distinguish between two types of abnormal respiratory pattern, obstructive and restrictive. There are several types of spirometers in use and they have been evolving since the first century AD.

Restrictive lung disease (RLD) impedes the expansion of the lungs on inspiration. This results in a decreased lung volume, forcing the individual to work harder to draw breath. Both ventilation and oxygenation are impaired. Pulmonary fibrosis, or scarring of the lung is one condition underlying RLD. The normal lung parenchyma becomes interspersed with scar tissue, resulting in a honeycomb appearance. Thankfully rare, pulmonary fibrosis is poorly understood, worsens over time and is often fatal.

Other conditions that contribute to restrictive lung disease include obesity, sarcoidosis (an autoimmune condition), scoliosis and neuromuscular diseases including amyotrophic lateral sclerosis (ALS) and muscular dystrophy (MD). The primary presenting symptom that drives people to the doctor is almost always difficulty in breathing. Sarcoidosis is characterized by swollen and reddened tissue called granulomas. These mostly affect the skin and the lungs. Some people develop symptoms suddenly and recover spontaneously after a few months or years. Others never experience any symptoms; the condition is incidentally following an x-ray for another reason.

Obstructive lung disorders (OLD) are diagnosed by the presence of obstructed and inflamed airways. Airflow is obstructed and the patient experiences difficulty breathing out. OLDs are are responsible for frequent trips to the hospital. Diseases which fall into the category of obstructive lung disorders include asthma, COPD and bronchitis. One thing these individuals have in common is inability to expire 70% of breath within a one-second time interval.

Asthma is caused by inflammation of the airways. One of the most common respiratory problems, it normally presents with wheezing, coughing and shortness of breath. Other, less frequent, symptoms, are fatigue, rapid breathing and sighing. Asthma can be life-threatening.

Cystic fibrosis (CF), a form of OLD, affects not only the lungs, but also the pancreas, intestine and liver. The most serious symptom is difficulty breathing. Advances in screening, diagnosis and treatment have resulted in a considerably improved prognosis for individuals with CF. In 1959, the the median age of survival was six months. By 2008, this had to risen to 37.5 years in the United States and, in Canada, from 24 to 47.7 in the years between 1982 and 2007. In Russia, where medical treatment is expensive and lung transplants are not performed, the median age of survival is 25 years of age.

The designation chronic obstructive pulmonary disease (COPD) includes conditions like chronic bronchitis and emphysema. With emphysema, the delicate lining of the lung becomes irreversibly damaged. This is usually a consequence of exposure to cigarette smoke, which restricts the patient's ability to breathe out. Although there is as yet no cure, removing the stimulus of cigarette smoke does bring improvement.

Spirometry is an essential screening tool for distinguishing between obstructive and restrictive lung diseases. Obstructive conditions include asthma, COPD and bronchitis. Both chronic bronchitis and emphysema contribute to chronic obstructive pulmonary disease. Restrictive lung diseases include pulmonary fibrosis, sarcoidosis, obesity hyperventilation syndrome, sarcoidosis, muscular dystrophy and amyotrophic lateral sclerosis (ALS).




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