Carbon Monoxide Poisoning: Clues to Unmasking the Great Masquerader

December 1, 2005

A 14-year-old boy was brought to theemergency department (ED) by paramedicsafter he complained of dizzinessand an episode of falling down earlythat morning when he awoke to go tothe bathroom.

A 14-year-old boy was brought to theemergency department (ED) by paramedicsafter he complained of dizzinessand an episode of falling down earlythat morning when he awoke to go tothe bathroom. His mother experienceda similar sensation of dizziness whenshe awoke to the sound of her son's fall.Paramedics reported that the boy hadto be carried out of the house becauseof his unsteady gait and depressedmental status. He received oxygen bymask during the 20 minutes of transporttime in the ambulance.

In the ED, the patient was alert,comfortable, and well-oriented. Furtherinquiry revealed that he had beencomplaining of dizziness and palpitationsfor the past 3 days. His motherreported that he had been evaluatedby his pediatrician on the previous dayand had received a diagnosis of "flu."

His vital signs were stable, and hehad an oxygen saturation of 97% whilebreathing room air. Results of the clinicalexamination were otherwise unremarkable.Capillary blood gas analysisby co-oximetry showed a pH of 7.4 anda partial pressure of carbon dioxide of35.1 mm Hg. The carboxyhemoglobin(COHb) level was 16.4%. Carbon monoxide(CO) poisoning secondary to useof a propane heater was the diagnosis.

As the weather gets colder, this casescenario takes on particular importance.First, it serves as a reminderthat most CO exposures occur duringthe winter, when use of indoorheating devices increases. Second, itunderscores the potential difficultyin recognizing CO poisoning. COpoisonings typically coincide withthe influenza season. Symptoms--which include dizziness, headache,drowsiness, and loss of consciousness--may also mimic those of theflu, food poisoning, gastroenteritis,or colic. Parents often seek the careof a pediatrician when these symptomsdevelop in their child. Hence