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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 diseases that fall under the definition of RLD include scoliosis, neuromuscular conditions such as amyotrophic lateral sclerosis (ALS), muscular dystrophy (MD), obesity and sarcoidosis. The common symptom that alerts people to the need to see a doctor is always shortness of breath. Sarcoidosis is an autoimmune condition in which the lungs become peppered with inflamed tissue referred to as granulomas. These mostly involve the lungs or the skin. Individuals may develop symptoms spontaneously and recover after a few months, maybe years. Other people never notice the condition and learn about it only after investigations for another condition.

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 term COPD covers conditions like emphysema and chronic bronchitis. In emphysema, the delicate tissues lining the lungs become irreversibly damaged, most commonly from exposure to cigarette smoke. This limits the person's ability to exhale. While there is no cure for emphysema, smoking cessation will reduce disease progression.

Spirometers are essential devices for diagnosing both restrictive and obstructive lung conditions. Obstructive lung diseases include COPD, bronchitis and asthma. Restrictive lung disorders refer to sarcoidosis, muscular dystrophy, amyotrophic lateral sclerosis, pulmonary fibrosis and obesity hyperventilation syndrome.




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