The Place Of The Spirometer In Diagnosing Lung Conditions

By Jaclyn Hurley


Spirometry is the most common type of test for examining lung function. It measures the volume and speed of air breathed in and out by the lungs. The spirometer is an essential tool in assessing conditions like asthma, cystic fibrosis, Chronic Obstructive Pulmonary Disorder (COPD) and pulmonary fibrosis. A spirogram can differentiate between two types of abnormal breathing patterns, restrictive and obstructive.

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 disorders that fall under the umbrella of RLD include the autoimmune condition, sarcoidosis; myscular dystrophy, amyotrophic lateral sclerosis (ALS), and obesity. Most patients present initially with difficulty breathing. Sarcoidosis is recognized by red, swollen lesions known as granulomas, mostly affecting the lungs and the skin. Some patients may suddenly develop symptoms that disappear spontaneously. Other people may never know they have sarcoidosis until they have an x-ray for another condition.

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.

Cystic fibrosis affects the lungs, liver, intestine and pancreas. Shortness of breath is the most serious symptom of cystic fibrosis. Improvements in diagnosis and treatment have extended the life span for people with CF. In 1959, the median survival age was 6 months. In the United States, it had increased to 37.5 years by 2008. In Canada, the median age at survival grew from 24 to 47.7 between 1982 and 2007. Patients are not so lucky in Russia, where lung transplants are not available and basic medical treatment is expensive. Here, the median age of survival is only 25 years.

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.

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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