Noninvasive measurement of carbon monoxide levels in ED patients with headache.

OBJECTIVES: Carbon Monoxide (CO), the third most common cause of acute poisoning death, is easily overlooked in the emergency department (ED). Nonspecific complaints such as headache, weakness, or malaise may easily result in misdiagnosis. The objectives of this study are to determine the frequency of CO poisoning in patients presenting to the ED complaining of headaches and to determine the feasibility of using noninvasive CO analyzers as a screening tool. METHODS: This prospective controlled study examined, during the winter months, adult patients presenting with a complaint of atraumatic, afebrile headaches. All subjects submitted a sample for a CO breath analyzer. Participants with elevated carboxyhemoglobin (COHb) levels (nonsmokers >2%, smokers >5%) underwent venous COHb testing. Control patients, without headaches, presenting to the ED were similarly studied. RESULTS: We enrolled 170 subjects and 98 controls. Of the 170 subjects, 12 (7.1%) had elevated COHb levels confirmed by venous COHb levels. Of the 98 controls, 1 (1.0%) had an elevated COHb level (p < 0.05). There were no differences in demographic factors between the two groups (p > 0.16). CONCLUSIONS: Noninvasive measurement of CO levels in ED patients with headaches is rapid and specific. During winter months, elevated CO levels are present in over 7% of ED patients with headaches.