MEDizzy - A 60-year-old man has been using a kerosene space heater and

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Chemotherapy and toxicology

A 60-year-old man has been using a kerosene space heater and candles to keep warm in the winter. He is transported to the hospital with complaints of severe headaches, nausea, dizziness, and a diminution in vision. He has a decreased arterial blood oxygen (O2)-carrying capacity, but no change of his arteria PO2. Which of the following most likely accounts for these findings?

ExplanationCarbon monoxide has an affinity for hemoglobin that is about 250 times greater than that of O2. It, therefore, binds to hemoglobin (forming carboxyhemoglobin) and reduces the O2-carrying capacity of the blood. The symptoms of poisoning are due to tissue hypoxia; they progress from headache and fatigue to confusion, syncope, tachycardia, coma, convulsions, shock, respiratory depression, and cardiovascular collapse. Carboxyhemoglobin levels below 15% rarely produce symptoms; above 40%, symptoms become severe. Treatment includes the establishment of an airway, supportive therapy, and administration of 100% (or hyperbaric) O2. Sulfur dioxide, ozone, and nitrogen dioxide are mucous membranes and respiratory irritants. Methane is a simple asphyxiant.