Carbon monoxide poisoning in 20-year old fireman

A 20-year-old fireman comes to the emergency room complaining of headache and dizziness after helping to put out a garage fire. He does not complain of shortness of breath, and the arterial blood gas shows a normal partial pressure of oxygen. Which of the following is the best first step in the management of this patient?

• a.Begin oxygen therapy
• b.Obtain chest x-ray
• c.Obtain carboxyhemoglobin level
• d.Obtain CT scan

The answer is c.

With symptoms of headache and dizziness in a fireman, the diagnosis of carbon monoxide poisoning must be addressed quickly. A venous or arterial measure of car-boxyhemoglobin must first be obtained, if possible, before oxygen therapy is begun.
The use of supplementary oxygen prior to obtaining the test may be a confounding factor in interpreting blood levels. Oxygen or even hyperbaric oxygen is given after blood for carboxyhemoglobin is drawn.

Chest x-ray should also be obtained. It may be normal or show a pattern of nonpulmonary edema, or aspiration in severe cases. Central nervous system imaging would not be indicated, and there are no diagnostic patterns that are specific to carbon monoxide poisoning.