Elsevier

Osteopathic Family Physician

Volume 5, Issue 2, March–April 2013, Pages 65-69
Osteopathic Family Physician

Office spirometry

https://doi.org/10.1016/j.osfp.2012.09.003Get rights and content

Chronic lung diseases carry a significant amount of morbidity and mortality. Obstructive lung diseases in particular are the fourth leading cause of death in the United States. Easily implemented in the primary care office, spirometry is a portable and useful tool to diagnose and monitor patients with chronic lung disease. The main goals of office spirometry are to measure a patient's ability to exhale forcefully, and to distinguish obstructive from restrictive lung disease. Indications include to evaluate the signs or symptoms of possible lung disease, to assess effectiveness of treatment for lung disease, and to follow-up or monitor progression of lung disease in primary care or in occupational health patients. It may also be used to assess a patient's baseline lung function if needed for insurance purposes or by some employers as part of pre-employment screening. Basic requirements to perform office spirometry are a well-trained operator, a suitable patient, and spirometry equipment that meets or exceeds the American Thoracic Society's standards for office spirometers. Interpretation of spirometry results should always be done in the context of the patient's clinical picture and never as isolated values that may or may not fall within the range of normal. Results obtained in the office can be analyzed to determine if the patient has obstructive, restrictive, or mixed lung disease, or if any airway obstructions are present. The test can also be repeated after the administration of a bronchodilator to determine if significant bronchodilation is present. Spirometry data can be monitored over time to optimize therapy and assess progression of patients with chronic lung disease.

Section snippets

Overview

Obstructive lung diseases, including chronic obstructive pul-monary disease (COPD), asthma, emphysema, and chronic bronchitis, as well as restrictive lung diseases, such as pulmonary fibrosis, carry a significant amount of morbidity and mortality. Obstructive lung disease in particular is the fourth leading cause of death in the United States, and it affects approximately 7% or more of those over the age of 50 years.1 The incidence of COPD increases with increasing age, particularly in patients

Indications

Office spirometry is indicated to evaluate signs or symptoms of possible lung disease, to assess effectiveness of treatment for lung disease, and to follow-up or monitor progression of lung disease. It may also be used to assess a patient's baseline lung function if needed for insurance purposes or by some employers as part of pre-employment screening.3

Office spirometry could play a role in secondary prevention of smoking. There is evidence that patients who smoke and have abnormal spirometry

Procedure

Basic requirements to perform office spirometry are a trained operator, a suitable patient, and spirometry equipment that meets or exceeds the ATS standards7 for office spirometers.

Spirometry can be physically demanding and patients selected for the test should be able to undergo the procedure. Testing is done with the patient in the seated position in order to avoid the possibility of falling due to dizziness or syncope. There should be a clear indication to perform the test, and the patient

Interpretation of spirometry results

In order to interpret spirometry results and determine if the test is normal or abnormal, 3 basic parameters are needed: FVC, FEV1, and the ratio of FEV1 to FVC. If there are values available for the SVC, and these are larger than the FVC, the SVC is to be used in place of the FVC for calculating the FEV1 to FVC ratio. The FVC is usually lower than the SVC in obstructive lung disease,7 therefore using the largest value available for the denominator will more accurately identify those patients

Obstructive disease

The hallmark of obstructive lung disease is an FEV1 to FVC ratio that is lower than the LLN. A reduced ratio indicates airflow narrowing during forced expiration. The spirogram typically shows a concave expiratory curve (Figure 2b).

As airway obstruction becomes more severe, the FEV1 will also be considerably reduced. However, if the FEV1 to FVC ratio is lower than the LLN and the FEV1 is normal, the results should be interpreted with caution since this pattern could be normal.10

An FEV1 which is

Bronchodilator response

After completion of spirometry, if reversible airway obstruction is suspected, an inhaled bronchodilator can be administered and the test repeated. This could be useful in distinguishing asthma from chronic bronchitis or emphysema. Diseases such as asthma typically exhibit significant bronchodilation, defined as an increase in either FEV1 or FVC of at least 12% also accompanied by a volume increase of at least 200 mL.14

A small percentage of patients with chronic bronchitis or emphysema will

Change over time

When performing repeat spirometry to monitor disease progression, the variables that will most consistently reflect the trend in pulmonary function are the FEV1 and FVC.7

A yearly decrease of 15% in FEV1 or FVC is considered clinically significant in patients with lung disease. In patients without lung disease, the change in FEV1 or FVC should exceed 15% before any clinical decisions are made, because test variability in normal patients usually exceeds the true annual decline in lung function,

Conclusions

With the proper training and equipment, office spirometry is a relatively simple way to diagnose and monitor patients with chronic lung disease. When spirometry results are properly interpreted in the context of the patient's clinical history and exam, office spirometry is an excellent point of care tool readily available to the osteopathic primary care physician.

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