A 50-year-old man comes to the emergency department after a motor vehicle collision. The patient was driving to the office in the morning when he fell asleep at a stop sign, his car rolled into an intersection, and a vehicle collided with his at low speed. The air bags did not deploy, but his coffee cup tipped over and spilled onto his right thigh. The patient reports that he slept 8 hours last night, which is typical, and he usually drinks a cup of coffee on the way to work to help him "wake up." Medical history includes hypertension. He works during the days at an accounting firm and lives alone with his cat. The patient does not use tobacco but drinks 1 or 2 beers on weekends. Blood pressure is 160/100 mm Hg, pulse is 88/min, and respiratory rate is 14/min. BMI is 36 kg/m². The patient is alert and oriented. Physical examination reveals only a small first-degree burn on the right thigh. The lungs are clear to auscultation and heart sounds are regular with no murmurs. Neurologic examination is normal. Which of the following is the most appropriate next step in management of this patient?

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This patient has caused a motor vehicle collision (MVC) due to falling asleep while driving. He does not have obvious behavioral risk factors for drowsy driving (eg, working nights, commercial driving), so a sleep disorder should be suspected. Given his hypertension and obesity, obstructive sleep apnea (OSA) is most likely and should be evaluated with overnight polysomnography. Although this patient gave a clear history, patients may withhold the information that they fell asleep while driving; drowsy driving should be suspected in single-vehicle crashes, off-road deviations, and rear-endings of other vehicles. All patients who fall asleep while driving should be evaluated for high-risk behaviors, use of sedating medications or alcohol, and sleep disorders (eg, OSA, narcolepsy). Others at risk for MVCs due to drowsy driving include medical house staff, law enforcement officers, and night or rotating shift workers. OSA increases the risk of MVCs 2-3 times; treatment with continuous positive airway pressure reduces this risk. Therefore, a very low threshold should exist for ordering a polysomnography in drowsy drivers. Even a low suspicion of a sleep disorder should prompt polysomnography in commercial drivers because their vehicles have a higher risk of causing mortality, as well as a higher economic cost, due to their larger size. (Choices A and D) Intermittent cardiac arrhythmias and seizures can cause momentary lapses in consciousness and lead to MVCs. However, this patient gave a clear history of falling asleep at a stop sign, so neither ECG monitoring nor electroencephalography is required. OSA is much more likely because of his hypertension and obesity. (Choice B) A CT scan of the brain should be obtained when the patient has significant head trauma after an MVC. This patient's loss of consciousness was due to sleepiness rather than trauma. (Choice E) Drowsy driving is extremely hazardous; reassurance is inappropriate. Sleep hygiene education is inadequate when there is likely an underlying sleep disorder. Education should instead focus on signs and symptoms of drowsy driving (eg, difficulty focusing, heavy eyelids, overlooking street signs). This patient should be advised to use other modes of transportation when drowsy. In addition, patients with suspected sleep disorders should be warned not to drive until therapy has proved effective. Educational objective: Patients involved in motor vehicle collisions due to drowsy driving should be evaluated for high-risk behaviors, use of sedating medications, and sleep disorders. Obstructive sleep apnea is frequently implicated in drowsy driving motor vehicle collisions; nocturnal polysomnography should be ordered to confirm the diagnosis. References: Asleep at the wheel-the road to addressing drowsy driving. (http://www.ncbi.nlm.nih.gov/pubmed/28364516) Continuous positive airway pressure reduces risk of motor vehicle crash among drivers with obstructive sleep apnea: systematic review and meta-analysis. (http://www.ncbi.nlm.nih.gov/pubmed/21061860) Obstructive sleep apnea and risk of motor vehicle crash: systematic review and meta-analysis. (http://www.ncbi.nlm.nih.gov/pubmed/20465027)

A 50-Year-Old Man Comes to the Emergency Department After a Motor