Review Question - QID 221229

This obese patient with morning headaches, daytime fatigue, and hypertension, most likely has obstructive sleep apnea. Treatment of obstructive sleep apnea with continuous positive airway pressure can prevent the development of right heart failure.

In obstructive sleep apnea, there is intermittent obstruction of the airway during sleep, resulting in transient hypoxia and poor sleep quality. During hypoxic episodes, the physiological response is pulmonary vasoconstriction to divert blood from lung areas with low oxygen tension to those with higher oxygen tension. When this process occurs chronically, as in sleep apnea, the persistent pulmonary vasoconstriction leads to vascular remodeling, leading to pulmonary arterial hypertension. As a result of pumping against higher pulmonary artery pressures, the right ventricle undergoes strain, hypertrophy, and eventual failure, which is known as cor pulmonale. This complication can be prevented by treating obstructive sleep apnea through weight loss and nocturnal continuous positive airway pressure therapy. Weight loss also improves compliance of the chest wall, allowing for reduced pleural pressure and reduced airway collapse. CPAP additionally maintains the patency of the airways by maintaining a positive end-expiratory pressure to prevent alveolar collapse.

Budev et al. review the pathogenesis and evaluation of cor pulmonale. They discuss the role of obstructive sleep apnea in pulmonary hypertension, resulting in right ventricular strain and failure. They recommend performing diagnostic studies early in order to allow for early treatment of this disease.

Figure/Illustration A is a depiction of a continuous positive airway pressure machine. The mask (red circle) provides airway support and can prevent pulmonary hypertension from developing.

Incorrect Answers:
Answer 1: Cirrhosis is a state of chronic liver failure that can be caused by alcoholic and non-alcoholic fatty liver disease. Cirrhosis presents with impaired liver biosynthetic function, manifesting as portosystemic varices, ascites, portal hypertension, palmar erythema, and spider angiomas.

Answer 2: Left heart failure has been associated with sleep apnea due to the systemic effects of hypoxia. While sleep apnea may contribute to the development and/or exacerbation of left heart failure, it is less likely than the correlation between sleep apnea and right heart failure. Left heart failure presents with poor exercise tolerance, dyspnea, jugular venous distension, edema, and cold extremities.

Answer 3: Lung cancer is typically the result of tobacco use. Lung cancer can present with cough, hemoptysis, and unintentional weight loss. It would be seen on chest radiograph as an abnormal area of consolidation or an irregular or calcified pulmonary nodule.

Answer 4: Pulmonary embolism has been associated with obstructive sleep apnea. While pulmonary emboli are associated with obesity, the most direct correlation with CPAP and outcomes is the prevention of right heart failure.

Bullet Summary:
Obstructive sleep apnea can be treated with continuous positive airway pressure and weight loss to prevent the development of right heart failure.