How much air remains in the lungs after a forced exhalation known as residual volume?

Residual volume is the amount of air that remains in the lungs after a forced exhalation, which is essential for maintaining gas exchange and preventing lung collapse during breathing. The typical value for residual volume in adults is around 1200 mL. This volume is important as it ensures that there is always some air in the lungs, allowing for continuous gas exchange even between breaths. Knowledge of this measurement helps perfusionists understand the respiratory capacity of patients during procedures.

The other values presented—3600 mL, 4800 mL, and 6000 mL—are significantly higher than the normal range for residual volume and represent either the total lung capacity or other lung volumes, such as vital capacity, which is the maximum amount of air a person can exhale after a maximum inhalation. Therefore, the most accurate option reflecting the typical residual volume in a healthy adult is indeed 1200 mL.