The Use Of A Spirometer To Diagnose Lung Disease

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.

A person with a restrictive lung disorder (RLD) has difficulty expanding the lungs when drawing in breath. This causes a decrease in lung volume and forces the lungs to work harder. Both oxygenation and ventilation are negatively affected. Pulmonary fibrosis, or scarring of the lungs, falls under the umbrella of RLD. Here, the normal tissue of the lung is dotted with lesions of scar tissue, creating a honeycomb-like appearance. Pulmonary fibrosis is badly understood, normally gets worse with time and is frequently fatal. Fortunately, it is a rare condition.

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 (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.

COPD encompasses diseases like chronic bronchitis and emphysema. In the case of emphysema, the inner surface of the lungs becomes permanently damaged, usually from exposure to cigarette smoke. Although there is no cure, removal of the trigger, cigarette smoking, results in an improved ability to exhale.

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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