What is indicated by increased use of intercostal muscles during breathing?

Increased use of intercostal muscles during breathing is indicative of severe respiratory distress. Normally, breathing is facilitated by the diaphragm, which is the primary muscle used for ventilation. However, when a person is experiencing respiratory distress—due to conditions such as asthma, COPD, pneumonia, or other respiratory illnesses—the body needs to recruit additional muscles to assist with inhalation. The intercostal muscles, located between the ribs, become significantly engaged to help expand the chest cavity and allow for greater airflow.

In severe respiratory distress, the body may struggle to achieve adequate ventilation, leading to a reliance on these accessory muscles to compensate for insufficient tidal volume or inadequate airway function. This physical sign is often accompanied by other symptoms such as rapid breathing, increased heart rate, or the use of abdominal muscles to assist with exhalation, demonstrating that the individual's breathing effort has substantially increased due to compromised respiratory function.