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.

In persons suffering from restrictive lung disease (RLD), the expansion of the lungs is impaired when breathing in. This causes a decrease in lung volume, making it more difficult for the person to breathe, impairing both oxygenation and ventilation. One type of condition underlying RLD is pulmonary fibrosis. Pulmonary fibrosis is associated with scarring of the lungs, resulting in a honeycomb-like appearance. While rare, the disease is poorly understood and is frequently 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.

The main features of obstructive lung disorders are obstructed and reddened airways. Airflow is obstructed, resulting in difficulty breathing out and, inevitably, numerous visits to the hospital. A diagnostic feature of OLD is the inability to expire 70% of breath in one second. Examples of OLD include COPD, bronchitis and asthma.

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.

The most serious symptom of CF is impaired breathing. Cystic fibrosis affects the lungs, pancreas, liver and intestine. Twenty-first century improvements in treatment and diagnosis have resulted in a much better prognosis than 50 or 60 years ago. In 1959, the median age of survival was only six months. As of 2008 in the United States, this had risen to 37.5 years; in Canada, it improved from 24 years in 1982 to 47.7 years in 2007. In Russia, the cost of medical treatment is often prohibitive and lung transplants do not take place. Here, the median age of survival is only 25 years.

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 important diagnostic tool in respiratory medicine. Distinguishing between obstructive and restrictive conditions, it enables doctors to inform interventions and determine prognoses.




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