Certified Registered Nurse Anesthetist (CRNA) Practice Exam

Stridor is most commonly observed during which phase of respiration?

1. Expiration

2. Inspiration

3. Quiet breathing

4. Speech

The correct answer is: Inspiration

Stridor is characterized by a high-pitched, wheezing sound resulting from turbulent airflow in the upper airway and is most commonly heard during inspiration. This occurs in conditions that lead to partial obstruction of the airway, such as laryngomalacia, croup, or foreign body obstruction. During inhalation, the negative pressure created in the thoracic cavity can exacerbate the effects of an obstruction, making stridor more prominent. Although stridor can occur in other circumstances, its distinct sound and relation to inspiratory effort are key indicators of an upper airway obstruction, particularly in pediatric populations where conditions like croup are common. Understanding the mechanics of breathing and the presentation of stridor can aid healthcare professionals in assessing and managing airway-related issues effectively.