Choice A. Benzodiazepines are sometimes used in managing cocaine toxicity, which can cause MI. However, dilated pupils and hyperstimulation (not drowsiness) would be expected.
Explanation
Educational objective: Carbon monoxide poisoning disrupts oxygen delivery and usage, which can cause clinical manifestations of myocardial ischemia. Elevated carboxyhemoglobin levels confirm the diagnosis. Severe cases require hyperbaric oxygen therapy.
Choice C and F. CT scan of the chest and transesophageal echocardiogram (TEE) are indicated if pulmonary (eg, interstitial lung disease) or cardiac (eg, valve abnormalities) processes are suspected. TEE is also used in patients with hemodynamic instability and concern for aortic dissection, which can cause chest pain and ECG changes but usually causes mediastinal widening on x-ray. This patient's presentation can be explained by CO poisoning; these studies risk further delaying management of CO poisoning without providing useful information.
Choice D. Pulmonary embolism can cause chest pain, dyspnea, ECG changes, hypertroponinemia, and rarely bilateral infiltrates. However, lactate elevation would be uncommon in the absence of a massive embolism causing obstructive shock and hypoperfusion. His oxygen saturation level (>90%) should not make him drowsy either. An ABG to check for carboxyhemoglobin level is much easier (and less contrast exposure) to obtain than CT angiogram.
Choice E. Metformin-induced lactic acidosis is unlikely to occur acutely and is not classically associated with MI. Although stopping metformin is necessary in this hospitalized patient with lactic acidosis, evaluation for CO poisoning is indicated.
Choice C and F. CT scan of the chest and transesophageal echocardiogram (TEE) are indicated if pulmonary (eg, interstitial lung disease) or cardiac (eg, valve abnormalities) processes are suspected. TEE is also used in patients with hemodynamic instability and concern for aortic dissection, which can cause chest pain and ECG changes but usually causes mediastinal widening on x-ray. This patient's presentation can be explained by CO poisoning; these studies risk further delaying management of CO poisoning without providing useful information.
