Question:medium
Oxygen therapy may NOT be useful (or may be harmful) in which of the following conditions?
Oxygen therapy may NOT be useful (or may be harmful) in which of the following conditions?
Show Hint
Recall the conditions (paraquat, bleomycin) where high oxygen worsens oxidative lung injury.
Updated On: Jun 23, 2026
- Asthma
- Pneumonia
- Subglottic stenosis
- Pulmonary fibrosis
Show Solution
The Correct Option is D
Solution and Explanation
Step 1: Frame the question as where oxygen does NOT fix the problem. Oxygen helps when hypoxaemia is reversible by raising alveolar $P_AO_2$. Asthma (bronchospasm), pneumonia (consolidation) and subglottic stenosis (airway obstruction) all respond to added oxygen. Step 2: Pulmonary fibrosis is a diffusion-limited disease; the alveolar-capillary membrane is thickened, so simply raising $FiO_2$ gives limited benefit. Step 3: Worse, hyperoxia drives reactive oxygen species that aggravate the same fibrotic and oxidative injury seen with bleomycin and paraquat. So oxygen is the wrong friend here. Step 4: Eliminate the others because each is an oxygen-responsive hypoxaemia, leaving fibrosis as the answer. \[\boxed{\text{Pulmonary fibrosis}}\]
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