chapter  17
34 Pages

The Cardiac Toxicity of Carbon Monoxide

Dedicated to my father. George Donald Penney. a fire captain , who. when I was a boy. warned me of the dangers of carbon monoxide.

Carbon monoxide (CO) has been the most common poison throughout history. It is an odorless, colorless, tasteless, nonirritating gas that is slightly less dense than air. It has been termed the "silent killer" . CO is produced in many processes where there is heat, fire, combustion, or oxidation. Particular types of industries (e.g., steel and iron foundries, petroleum refining, pulp and paper mills) have long been recognized to be especially hazardous with regard to CO exposure. Workers are also exposed to CO when working near internal combustion engines, such as in automotive garages. Accidental fires may also produce large amounts of CO which affect both the ftre victims and the fire fighters. By far the greatest source of individual exposure to CO is tobacco smoke. Cigarette smoke contains about 4% CO, while the CO

CO binds to heme-containing proteins, rendering them incapable of normal function. Probably as its major action, the oxygen-carrying capacity of hemoglobin is progressively reduced. In contrast to simple anemia, however, CO uptake by the hemoglobin molecule results in a tighter binding of the remaining oxygen, which is observed as a left-shift ofthe hemoglobin-oxygen association-dissociation curve. Oxygen diffusion to tissues then must occur at a lower P02 , thus enhancing tissue hypoxia.