Rosh Internal Medicine Boost Practice Exam

In a patient with obesity hypoventilation syndrome, what is the best initial therapy?

1. Nocturnal bilevel positive airway pressure

2. Nocturnal continuous positive airway pressure

3. Oral theophylline dosed every twelve hours

4. Twenty-four hour supplemental oxygen

The correct answer is: Nocturnal continuous positive airway pressure

In obesity hypoventilation syndrome (OHS), the best initial therapy is nocturnal continuous positive airway pressure (CPAP). CPAP is effective for patients with OHS because it improves ventilation and oxygenation during sleep. This patient population often experiences hypoventilation, particularly during sleep, due to the excess weight compromising respiratory function. By delivering a continuous stream of air, CPAP helps keep the airways open and facilitates better gas exchange. Nocturnal bilevel positive airway pressure (BiPAP) could also be used, especially in more severe cases where there are significant problems with both inspiratory and expiratory pressures, but CPAP is generally the first-line therapy because it is simpler and typically sufficient for mild to moderate cases. Other options like oral theophylline and supplemental oxygen do not address the underlying hypoventilation directly. Theophylline may have some bronchodilator effects, but it is not a first-line treatment for OHS and can have significant side effects. Supplemental oxygen can improve oxygen saturation but does not correct the hypoventilation itself, which can lead to further carbon dioxide retention and worsening of the condition. Therefore, nocturnal continuous positive airway pressure is the most appropriate initial therapy for managing obesity hypov