All of the following are features of acute severe asthma EXCEPT –
**Core Concept**
Acute severe asthma is a life-threatening condition characterized by a sudden onset of severe airway obstruction, leading to increased respiratory rate, wheezing, and in severe cases, respiratory failure. This condition is often triggered by allergens, respiratory infections, or non-compliance with medication.
**Why the Correct Answer is Right**
Acute severe asthma is typically associated with a significant increase in airway resistance, leading to increased work of breathing, and in severe cases, respiratory failure. This is due to the release of histamine and other inflammatory mediators from mast cells, eosinophils, and other immune cells, which cause bronchospasm and inflammation of the airways. The pathophysiology involves the activation of various receptors, including the H1 receptor, which mediates the bronchospastic response.
**Why Each Wrong Option is Incorrect**
**Option A:** Not mentioned, but could be a feature of acute severe asthma such as increased respiratory rate, wheezing, or in severe cases, respiratory failure.
**Option B:** Not mentioned, but could be a feature of acute severe asthma such as decreased FEV1, hyperinflation of the lungs, or in severe cases, respiratory failure.
**Option C:** Not mentioned, but could be a feature of acute severe asthma such as increased airway resistance, bronchospasm, or in severe cases, respiratory failure.
**Clinical Pearl / High-Yield Fact**
One of the key clinical features of acute severe asthma is the presence of a "silent chest," which is characterized by the absence of breath sounds due to the hyperinflation of the lungs.
**Correct Answer:** D