Desaturation during sleep with nasal flow decreased and respiratory effort decreased indicates which apnea type?

• A. Obstructive apnea
• B. Central apnea
• C. Mixed apnea
• D. Hypoventilation

Answer: (B)

Central apnea is the situation where the brain fails to initiate breathing during sleep, so there is little to no respiratory effort and little to no airflow. When this occurs, nasal flow decreases and oxygen saturation drops because ventilation has effectively stopped. That combination—desaturation with reduced or absent respiratory effort during the event—fits a central origin. In obstructive apnea, the airway collapses but the respiratory muscles still drive breaths, so respiratory effort remains present even though airflow is reduced or paused; desaturation happens with ongoing effort. Mixed apnea starts as central and then becomes obstructive, so you’d see an initial lack of effort followed by resumed effort with airflow. Hypoventilation involves generally reduced ventilation with continued, though insufficient, airflow, but not complete cessation tied to loss of respiratory drive.