A 22-year-old woman with known asthma presents to the emergency department with a severe attack. She is drowsy, the chest is strikingly quiet on auscultation despite marked distress, and peak expiratory flow is 25% of her personal best. Arterial gas shows pH 7.31, PaCO2 52 mmHg, PaO2 58 mmHg. Which single feature in this presentation marks the transition to life-threatening asthma?
- A Silent chest on auscultation ✓
- B Peak expiratory flow below 50% of predicted
- C Use of accessory muscles of respiration
- D Heart rate of 118 per minute
Correct answer: A. Silent chest on auscultation
Explanation
B silent chest indicates airflow so poor that not enough air moves to generate wheeze, and it is a recognised sign of life-threatening asthma along with exhaustion, cyanosis, bradycardia, hypotension and a normal or rising PaCO2. Accessory muscle use and heart rate above 110 indicate severe but not yet life-threatening attacks, and PEF below 50% defines severe rather than life-threatening severity.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.