During a sleep study, the patient's respiratory effort continues while nasal air flow stops. These results should be interpreted as

• A. Normal sleep pattern
• B. Hypoxia
• C. Obstructive sleep apnea
• D. Central apnea

Answer: (C)

The situation reflects an obstructive event. When the respiratory drive continues (effort) but nasal airflow stops, it means the brain is signaling to breathe but the upper airway is collapsing or blocked, preventing air from entering the lungs. This is the hallmark of obstructive sleep apnea: ongoing respiratory effort with absent airflow due to mechanical airway obstruction during sleep. In contrast, central apnea would show a lack of respiratory effort as well as no airflow because the brain isn’t signaling to breathe. Normal sleep would have both airflow and effort synchronized, with no recurrent obstruction. Hypoxia can accompany obstructive events but isn’t the pattern itself.