Question
In moderate severity obstructive lung disease, the expected abnormalities include the following except
The correct answer is
$\downarrow$ FRC/TLC ratio
Understanding Obstructive Lung Disease Abnormalities
Obstructive lung disease is characterized by airflow limitation, meaning it's harder to exhale air quickly. This often results from narrowing or collapse of airways. Pulmonary Function Tests (PFTs) help quantify these changes.
Pulmonary Function Test Findings in Obstruction
In obstructive lung disease, PFTs typically show:
- A reduced ratio of Forced Expiratory Volume in 1 second (FEV1) to Forced Vital Capacity (FVC), often expressed as $FEV_1$/FVC $< 70\%$(or below the lower limit of normal). This is the primary indicator of airflow obstruction.
- Increased lung volumes like Residual Volume (RV) and Functional Residual Capacity (FRC) due to air trapping.
- Total Lung Capacity (TLC) may be normal or increased.
- Vital Capacity (VC) can be normal or decreased, particularly as severity increases.
Analyzing the Options as Exceptions
Let's evaluate each option based on typical findings in moderate obstructive lung disease:
- Option 1: $\uparrow$ Residual capacity: Increased RV is expected due to air trapping. This is NOT the exception.
- Option 2: $\downarrow$ Vital capacity: Vital capacity can decrease in obstructive lung disease, especially with moderate to severe obstruction. This is a possible finding, NOT the exception.
- Option 3: $\downarrow$ FRC/TLC ratio: In obstruction, FRC usually increases, and TLC might increase or stay normal. This typically leads to an increased FRC/TLC ratio. A decrease in this ratio is contrary to the expected findings. Therefore, this IS the exception.
- Option 4: $FEV_1$/FVC $< 70\%$: A reduced FEV1/FVC ratio is the defining characteristic of obstructive lung disease. This is expected, NOT the exception.
Conclusion
The abnormality not typically expected in moderate obstructive lung disease is a decreased FRC/TLC ratio. The expected finding is an increased ratio.
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Important Questions from COPD
- The distance walked in 6 minutes is an indirect measure of which of the following variables of the 'BODE Index' which is used to assess the prognosis in chronic obstructive pulmonary disease?
- The most common cause of chronic type II respiratory failure is:
- Which of the following are categorised under obstructive lung disease ?
1. Bronchial asthma
2. Bronchiectasis
3. Bronchiolitis
4. Pulmonary sarcoidosis
Select the correct answer using the code given below: - Risk factors for development of COPD include which of the following ?
1. Tobacco smoking
2. Recurrent infection
3. Coal dust exposure
4. High socio-economic status
Select the correct answer using the code given below: - A 65-year-old male smoker has been diagnosed with Chronic Obstructive Pulmonary Disease (COPD). On pulmonary function testing, the $FEV_1/FVC < 0.7$ and $FEV_1 = 42\%$ of predicted. The severity of airflow obstruction in this patient as per GOLD criteria is :
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