How are spirometry results interpreted?

Spirometry results are interpreted by comparing the patient’s lung function measurements to established reference values. Here’s a general guide to interpreting spirometry results:

1. Forced Expiratory Volume in 1 Second (FEV1): This measures the amount of air a person can forcefully exhale in the first second of the test. It’s often expressed as a percentage of the predicted or expected value for a person of the same age, sex, height, and race. A lower FEV1 percentage indicates impaired lung function.
2. Forced Vital Capacity (FVC): FVC measures the total amount of air a person can exhale during the test. It’s also expressed as a percentage of the predicted value. A reduced FVC suggests restricted lung capacity.
3. FEV1/FVC Ratio: This ratio represents the percentage of FVC expelled in the first second. A lower FEV1/FVC ratio may indicate obstructive lung diseases like asthma or chronic obstructive pulmonary disease (COPD).
4. Peak Expiratory Flow (PEF): PEF measures the maximum speed of air exhaled during the test. It’s commonly used for monitoring asthma. Lower PEF values suggest worsening asthma control.
5. Interpretation: Based on these measurements, spirometry results are classified into different categories:
   • Normal: Lung function falls within the expected range for the individual.
   • Obstructive Pattern: Reduced FEV1/FVC ratio, often seen in conditions like asthma and COPD.
   • Restrictive Pattern: Reduced FVC with normal or near-normal FEV1/FVC ratio, indicative of restrictive lung diseases or conditions affecting lung expansion.
   • Mixed Pattern: A combination of obstructive and restrictive patterns, seen in complex lung disorders.
6. Severity: In cases of abnormal results, the severity of the condition is often classified as mild, moderate, severe, or very severe, depending on how far the results deviate from the expected values.

It’s crucial to note that interpretation should be done by a qualified healthcare provider, considering the patient’s medical history, symptoms, and other clinical information. Spirometry results alone may not provide a complete diagnosis and should be used in conjunction with other assessments and tests. Always consult your healthcare provider for a comprehensive evaluation and personalized treatment plan.