Nightly reliance on CPAP in a morbidly obese patient most strongly points to sleep-disordered breathing, and in the context of severe obesity (BMI 45), it raises concern forobesity hypoventilation syndrome (OHS), which is characterized byalveolar hypoventilation(chronic hypoventilation with hypercapnia) that is not fully explained by other pulmonary or neuromuscular causes. While CPAP is commonly prescribed for obstructive sleep apnea, severe obesity increases the likelihood of associated hypoventilation physiology; in outpatient CDI review, this becomes a documentation opportunity to ensure the provider specifies whether the patient has OSA alone versus OSA with OHS/alveolar hypoventilation, because the latter reflects higher clinical complexity and requires clear monitoring/management (e.g., ABGs or bicarbonate trends, symptoms of hypoventilation, adherence, need for BiPAP). Heart failure and pulmonary edema are not implied by CPAP use, and essential hypertension is common in obesity but not the condition most specifically linked to CPAP dependence. Therefore, alveolar hypoventilation is the best supported answer.