A 32-year-old man comes to the emergency department due to a throbbing frontal headache that began during the night and slowly worsened. The patient has also had nausea with lightheadedness. "It's the oddest thing. It seemed like a migraine at first, but when my wife began having similar symptoms, I realized it must be the flu or something." The patient has no medical problems and takes no medications. He does not use tobacco, alcohol, or illicit drugs. He and his wife are renovating their older home. They recently retiled the bathrooms and are now considering replacing some of the major appliances as they are quite old. Temperature is 36.7 C (98.1 F), blood pressure is 120/76 mm Hg, pulse is 90/min, and respirations are 18/min. Pulse oximetry is 97% on ambient air. Mucous membranes are moist, and pupils are equal and reactive to light. Auscultation of the heart and lungs is normal. No neck rigidity or meningeal signs are present. Neurologic examination is normal. Diagnostic tests, including complete blood count, metabolic panel, and arterial blood gas with co-oximetry, are ordered. Which of the following is the most appropriate next step in management of this patient?

Question

A 32-year-old man comes to the emergency department due to a throbbing frontal headache that began during the night and slowly worsened.  The patient has also had nausea with lightheadedness.  "It's the oddest thing.  It seemed like a migraine at first, but when my wife began having similar symptoms, I realized it must be the flu or something."  The patient has no medical problems and takes no medications.  He does not use tobacco, alcohol, or illicit drugs.  He and his wife are renovating their older home.  They recently retiled the bathrooms and are now considering replacing some of the major appliances as they are quite old.  Temperature is 36.7 C (98.1 F), blood pressure is 120/76 mm Hg, pulse is 90/min, and respirations are 18/min.  Pulse oximetry is 97% on ambient air.  Mucous membranes are moist, and pupils are equal and reactive to light.  Auscultation of the heart and lungs is normal.  No neck rigidity or meningeal signs are present.  Neurologic examination is normal.  Diagnostic tests, including complete blood count, metabolic panel, and arterial blood gas with co-oximetry, are ordered.  Which of the following is the most appropriate next step in management of this patient?

Quizplus · Accepted Answer

Explanation: 11ec2b69_c19a_7b9e_8f63_f7ecbf131fad_MD0005_00 This patient and his wife developed concurrent headaches, nausea, and lightheadedness while in a home with older appliances, raising suspicion for carbon monoxide (CO) poisoning. CO is a colorless, odorless gas that binds heme with a much greater affinity than oxygen and interferes with oxygen offloading at the tissue level. Toxic exposure largely occurs in the setting of poorly functioning heating systems or improperly vented fuel-burning devices (eg, kerosene heaters). Mild cases are marked by flu-like symptoms (eg, headache, malaise, nausea, dizziness); more severe cases often present with seizure, syncope, coma, and/or myocardial ischemia. CO poisoning is often suspected when several people in a shared environment develop symptoms of the disorder. Confirmation is generally made when arterial blood gas analysis shows elevated carboxyhemoglobin levels (pulse oxymetry cannot differentiate between oxyhemoglobin and carboxyhemoglobin and cannot be used for diagnosis). Initial treatment with high-flow oxygen through a nonrebreathing face mask typically resolves the symptoms, but hyperbaric oxygen may be required for those with severe toxicity. (Choice B) CO poisoning is life-threatening, and the treatment is low risk. Treatment should not be delayed while awaiting confirmation of the diagnosis. (Choice C) Acute migraines often cause headaches, nausea, and dizziness and are frequently treated with sumatriptan. This patient who has no history of migraine and who developed symptoms simultaneously with his wife is more likely to have CO poisoning. (Choice D) Acute meningitis is usually diagnosed with lumbar puncture and treated with antibiotics. Although meningitis can cause headaches, fatigue, and nausea, most patients also have fever, altered mental status, and/or nuchal rigidity. (Choice E) Influenza can be treated with oseltamivir. Although many cases are associated with headache and fatigue, most patients also have fever, cough, rhinorrhea, sore throat, and myalgias. Educational objective: Symptoms of carbon monoxide poisoning include headache, nausea, malaise, and dizziness. Suspicion should be raised when several people who share a common environment develop concurrent symptoms. Diagnosis is confirmed by arterial blood gas analysis with carboxyhemoglobin level; treatment with high-flow oxygen through a nonrebreathing mask is generally curative, but patients with severe toxicity may require hyperbaric oxygen.

A 32-Year-Old Man Comes to the Emergency Department Due to a Throbbing