Inward movement of chest muscles due to reduced intrathoracic pressure indicates what?

• A. Tachypnea
• B. Apnea
• C. Bradypnea
• D. Retractions

Answer: (D)

During inspiration, the body pulls air into the lungs by making the intrathoracic pressure more negative. When the work of breathing is increased—because airways are narrowed or the lungs are stiff—the chest wall pulls inward as the accessory muscles work harder. This inward movement of the chest wall is called retractions and signals increased respiratory effort or distress. The other terms describe breathing rate or the absence of breathing, not this chest-wall indrawing pattern.