Thursday, March 27, 2014

The Use Of A Spirometer To Diagnose Lung Disease

By Jaclyn Hurley


One of the primary tests for assessing lung disorders is the use of spirometry. A spirometer measures the speed and volume of air inspired and expired by the pulmonary system. It plays a critical role in evaluating conditions like cystic fibrosis, pulmonary fibrosis, chronic obstructive pulmonary disease and asthma. A spirogram will tell the diagnostician whether a patient has one of two categories of abnormal lung function, obstructive or restrictive.

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.

One of the most common respiratory ailments, asthma most often features wheezing, coughing and breathlessness. Less commonly, patients experience fatigue, rapid breathing and appear to sigh frequently. Occasionally, asthma may 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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