What is the interpretation of a spirometry result showing a Forced Vital Capacity (FVC) of 74%, a Forced Expiratory Volume in one second to Forced Vital Capacity ratio (FEV1/FVC) of 83%, and a Forced Expiratory Volume (FEV) of 88%?

From the Guidelines

The spirometry results indicate a mild restrictive pattern, with a reduced FVC of 74% of predicted, a normal FEV1/FVC ratio of 83%, and a relatively preserved FEV1 of 88% of predicted, suggesting a restrictive lung disorder rather than obstructive disease. This pattern is characterized by reduced lung volumes with preserved airflow, as indicated by the normal FEV1/FVC ratio 1. The most important parameter for identifying an obstructive impairment is the FEV1/VC ratio, but in this case, it is normal, suggesting that the patient does not have an obstructive lung disease 1. Common causes of restrictive lung disorders include interstitial lung diseases, chest wall abnormalities, neuromuscular disorders, pleural diseases, or obesity 1. Further evaluation is recommended, including:

• Complete pulmonary function tests with lung volumes and diffusion capacity
• Chest imaging
• Clinical correlation with symptoms and medical history Treatment would depend on the underlying cause of the restriction, and may include:
• Anti-inflammatory medications for interstitial disease
• Weight loss for obesity-related restriction
• Specific treatments for other identified causes Unlike obstructive disorders, bronchodilators are typically not effective for purely restrictive conditions unless there is a mixed component 1. Management focuses on treating the underlying condition, and the severity of the lung function impairment can be categorized based on the FEV1 % predicted, with a mild severity corresponding to an FEV1 % predicted of >70% 1. It is essential to interpret the spirometry results in the context of the patient's symptoms, medical history, and other diagnostic tests to determine the underlying cause of the restrictive pattern and develop an appropriate treatment plan 1.

From the Research

Spirometry Results Interpretation

The given spirometer results are: FVC 74, FEV1/FVC 83, FEV 88. To interpret these results, we need to consider the following points:

• FVC (Forced Vital Capacity) is 74, which is lower than the normal range, indicating a possible restrictive pattern.
• FEV1/FVC (Forced Expiratory Volume in 1 second/Forced Vital Capacity) is 83, which is higher than the normal range, indicating a possible restrictive pattern 2.
• FEV (Forced Expiratory Volume) is 88, which is lower than the normal range, indicating a possible obstructive pattern.

Restrictive Pattern

A restrictive pattern is characterized by a reduced FVC and a normal or increased FEV1/FVC ratio 2. In this case, the FVC is reduced, and the FEV1/FVC ratio is increased, suggesting a restrictive pattern.

• However, the study by 2 suggests that the use of an increased FEV1/FVC ratio as a mandatory condition for diagnosing a restrictive pattern may diminish the sensitivity of the test and hamper the diagnosis of restrictive ventilatory defect in spirometry, especially in mild and moderate stages.

Obstructive Pattern

An obstructive pattern is characterized by a reduced FEV1/FVC ratio 3. In this case, the FEV1/FVC ratio is increased, which does not suggest an obstructive pattern.

• However, the study by 4 suggests that a reversible restrictive pattern on spirometry may be a variant of obstructive lung disease, and a therapeutic trial of bronchodilators may be beneficial in symptomatic patients.

Severity of Restriction

The severity of restriction can be assessed using the ATS/ERS guidelines, which suggest that a reduction in FEV1 be used for categorizing both obstructive and restrictive abnormalities 5.

• However, the study by 5 suggests that the new ATS/ERS guidelines may give lower severity scores for restrictive lung diseases in up to 25% of patients, and the level of severity of restriction cannot be described interchangeably between the old and new guidelines for all patients.

Key Points

• The spirometer results suggest a possible restrictive pattern, but the use of an increased FEV1/FVC ratio as a mandatory condition for diagnosing a restrictive pattern may diminish the sensitivity of the test.
• A reversible restrictive pattern on spirometry may be a variant of obstructive lung disease, and a therapeutic trial of bronchodilators may be beneficial in symptomatic patients.
• The severity of restriction can be assessed using the ATS/ERS guidelines, but the level of severity of restriction cannot be described interchangeably between the old and new guidelines for all patients 2, 4, 3, 5.