Master PALS 2026 – Ace the RQI Pediatric Lifesaver Challenge!

During spontaneous breathing, the inspiratory muscles contract to expand the chest. The diaphragm moves downward and the rib cage lifts outward, increasing intrathoracic volume. As the thoracic cavity enlarges, intrathoracic pressure becomes more negative, creating a pressure gradient that pulls air into the lungs. So the inspiratory muscles are aimed at increasing intrathoracic volume to draw air in. Decreasing thoracic volume would push air out, staying at the same volume wouldn’t generate airflow, and increasing abdominal pressure isn’t the mechanism driving inspiration.