FEVI/FVC is decrease in:
**Core Concept**
The FEVI/FVC ratio is a crucial parameter in pulmonary function tests, indicating the proportion of the vital capacity (VC) that can be exhaled in the first second. It is a vital marker for assessing the severity of obstructive and restrictive lung diseases.
**Why the Correct Answer is Right**
A decrease in the FEVI/FVC ratio is indicative of obstructive lung disease, such as chronic obstructive pulmonary disease (COPD) or asthma. In these conditions, the airways are narrowed or constricted, leading to an increased resistance to airflow and a delay in the exhalation of air. As a result, the FEVI (the volume of air exhaled in the first second) decreases, while the FVC (the total volume of air exhaled) remains relatively preserved, leading to a decreased FEVI/FVC ratio.
**Why Each Wrong Option is Incorrect**
* **Option A:** Typically, a decrease in FEVI/FVC is not seen in restrictive lung diseases, where both FEVI and FVC are decreased, leading to a normal or even increased FEVI/FVC ratio. Restrictive diseases include conditions such as pulmonary fibrosis or sarcoidosis.
* **Option B:** This option is incomplete and does not provide a valid distractor.
* **Option C:** This option is incomplete and does not provide a valid distractor.
**Clinical Pearl / High-Yield Fact**
Remember the mnemonic "FEV1/FVC < 70% in obstructive lung disease" to help you recall the significance of a decreased FEVI/FVC ratio in assessing obstructive lung diseases.
**Correct Answer: D. Obstructive lung disease.**