The Place Of The Spirometer In Diagnosing Lung Conditions

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.

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 disease (OLD) is characterized by inflamed and obstructed airways. OLD obstructs airflow, leading to difficulty exhaling and frequent trips to the hospital. Bronchitis, asthma and COPD are examples of obstructive lung diseases. A common feature of OLD is loss of the ability to exhale 70 percent of breath within one second.

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.

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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