A 42-year-old man comes to the physician with complaints of daytime sleepiness, dyspnea on exertion, and impaired concentration. His other medical problems include hypertension and type 2 diabetes mellitus.
His temperature is 36.1° C (97° F) , blood pressure is 162/85 mm Hg, pulse is 92/min, and respirations are 14/min. His BMI is 40 kg/m². The patient's pulse oximetry is 94% on room air. Examination shows jugular venous distention, clear lung fields, loud second heart sound, and 2+ pretibial edema bilaterally.
Laboratory results are as follows:

Chest x-ray shows low lung volumes but is otherwise unremarkable. Spirometry shows a FEV₁ of 70% of predicted and a FEV₁/FVC ratio of 90%. Transthoracic echocardiography is limited by body habitus but shows mild right ventricular enlargement.
Which of the following is the best initial therapy for this patient?

Question

A 42-year-old man comes to the physician with complaints of daytime sleepiness, dyspnea on exertion, and impaired concentration. His other medical problems include hypertension and type 2 diabetes mellitus.
His temperature is 36.1° C (97° F) , blood pressure is 162/85 mm Hg, pulse is 92/min, and respirations are 14/min. His BMI is 40 kg/m². The patient's pulse oximetry is 94% on room air. Examination shows jugular venous distention, clear lung fields, loud second heart sound, and 2+ pretibial edema bilaterally.
Laboratory results are as follows:

Chest x-ray shows low lung volumes but is otherwise unremarkable. Spirometry shows a FEV₁ of 70% of predicted and a FEV₁/FVC ratio of 90%. Transthoracic echocardiography is limited by body habitus but shows mild right ventricular enlargement.
Which of the following is the best initial therapy for this patient?

Quizplus · Accepted Answer

This patient most likely has obesity hypoventilation syndrome (OHS), also known as Pickwickian syndrome. The symptoms of OHS are due primarily to coexisting obstructive sleep apnea. OHS is confirmed in individuals with BMI > 30 kg/m², arterial blood gas level on room air documenting presence of daytime hypercapnia, and when an alternate cause of the hypoventilation cannot be identified. Elevated serum bicarbonate level and secondary erythrocytosis may also indicate the presence of chronic hypercapnia and chronic hypoxemia, respectively. The alveolar-arterial oxygen gradient should be calculated as normal gradient on room air makes pulmonary parenchymal or airway disease unlikely. obesity hypoventilation syndrome (OHS) The general approach to patients with OHS includes weight reduction, nocturnal positive-pressure ventilation, and avoidance of sedative medications. Positive-pressure ventilation decreases nocturnal and daytime PaCO₂, leading to reduction in daytime sleepiness and improved quality of life. Nighttime polysomnography testing should be done to identify any underlying sleep disorder and to individualize treatment with continuous positive-airway pressure or noninvasive positive-pressure mechanical ventilation. Patients should be encouraged to lose weight. However, positive-pressure ventilation should not be delayed while patients attempt to do so (Choices B and E). Bariatric surgery can be considered for those who fail to lose significant weight despite lifestyle modifications. Patients should be cautioned to avoid alcohol, benzodiazepines, and opiates as sedatives worsen nocturnal desaturation. Chronic oxygen therapy may be required with pO₂ < 90% or PaO₂ < 60 mm Hg (Choice C). Acetazolamide, a carbonic anhydrase inhibitor, is a respiratory stimulant that can be used if positive-pressure ventilation fails (Choice A). Educational objective: The management of obesity hypoventilation syndrome includes weight reduction, nocturnal positive-pressure ventilation, and avoidance of sedative medications. Patients should be encouraged to lose weight, but positive-pressure ventilation should not be delayed while they attempt to do so. __________ References: Clinical guideline for the evaluation, management and long-term care of obstructive sleep apnea in adults. (http://www.ncbi.nlm.nih.gov/pubmed/19960649) Daytime hypercapnia in obstructive sleep apnea syndrome. (http://www.ncbi.nlm.nih.gov/pubmed/18079218) Obesity hypoventilation syndrome: mechanisms and management. (http://www.ncbi.nlm.nih.gov/pubmed/21037018)

A 42-Year-Old Man Comes to the Physician with Complaints of Daytime