Severe Asthma Exacerbation
A staged clinical reasoning case
Before you begin
This fictional composite case progresses through seven clinical decisions. Choose a response before the reasoning appears. The activity is unscored and takes approximately 10–15 minutes.
Later findings remain hidden until you complete the current stage.
Case debrief
The patient progressed from increased respiratory drive to failing ventilation. The second ABG appears nearly normal if read in isolation; the trend and bedside findings reveal the danger.
| Finding | Initial | After deterioration | Interpretation |
|---|---|---|---|
| pH | 7.47 | 7.38 | Loss of initial alkalemia despite continued distress |
| PaCO₂ | 31 mmHg | 42 mmHg | A clinically important rise toward “normal” as ventilation fails |
| PaO₂ | 61 mmHg on room air | 65 mmHg on supplemental oxygen | Persistent gas-exchange impairment despite oxygen therapy |
| Clinical state | Alert, tachypneic, diffuse wheeze | Drowsy, lower respiratory rate, quiet chest | Apparent calming represents exhaustion, not recovery |
Clinical reasoning priorities
- Exacerbation severity depends on the entire presentation rather than one vital sign.
- Hypoxemia can persist despite tachypnea because ventilation remains uneven.
- A normalizing PaCO₂ may be more dangerous than an obviously high value when it rises during persistent distress.
- Diminishing wheezing can reflect critically reduced airflow.
- Intubation should follow evidence of clinical deterioration rather than wait for respiratory arrest.
- Mechanical ventilation must allow enough time for exhalation.
Differential diagnosis
Asthma best explains this presentation, but acute dyspnea and wheezing may also result from anaphylaxis, pulmonary embolism, pneumothorax, pneumonia, cardiogenic pulmonary edema, or upper-airway obstruction such as inducible laryngeal obstruction. New focal findings, fever, urticaria, angioedema, hypotension, unilateral breath sounds, pleuritic pain, or poor response to appropriate treatment should prompt reconsideration of the diagnosis (Cahill, 2026; GINA, 2026).
References
Cahill, K. N. (2026). Acute exacerbations of asthma in adults: Emergency department and inpatient management. In T. W. Post (Ed.), UpToDate. Retrieved September 20, 2026, from https://www.uptodate.com/contents/acute-exacerbations-of-asthma-in-adults-emergency-department-and-inpatient-management
Gayen, S., Dachert, S., Lashari, B. H., Gordon, M., Desai, P., Criner, G. J., Cardet, J. C., & Shenoy, K. (2024). Critical care management of severe asthma exacerbations. Journal of Clinical Medicine, 13(3), 859. https://doi.org/10.3390/jcm13030859
Global Initiative for Asthma. (2026). Asthma management and prevention for adults, adolescents and children 6–11 years: A summary guide for healthcare providers. https://ginasthma.org/wp-content/uploads/2026/07/GINA-Summary-Guide-2026-WEB-WMS.pdf
Mein, S. A., & Ferrera, M. C. (2025). Management of asthma and COPD exacerbations in adults in the ICU. CHEST Critical Care, 3(1), 100107. https://doi.org/10.1016/j.chstcc.2024.100107
Sisson, T. H., Claar, D., Chesnutt, M. S., & Prendergast, T. J. (2019). Pulmonary disease. In G. D. Hammer & S. J. McPhee (Eds.), Pathophysiology of disease: An introduction to clinical medicine (8th ed.). McGraw-Hill Education.
Sullivan, R., & Leibner, E. (2026). Airway management in acute severe asthma for emergency medicine and critical care. In T. W. Post (Ed.), UpToDate. Retrieved September 20, 2026, from https://www.uptodate.com/contents/airway-management-in-acute-severe-asthma-for-emergency-medicine-and-critical-care