Behavioral Effects of Carbon Monoxide Exposure: Results and Mechanisms

Short-term exposure to carbon monoxide (CO) will produce frank behavioral effects if carboxyhemoglobin (COHb) rises to sufficiendy high levels. Although there are many reports of effects below the level of COHb needed to produce unconsciousness, there are always equally persuasive reports of no effects at the same or greater COHb. The rise in BBF due to COHb increase has been observed indirectly in humans. It was also observed that a considerable difference exists among individual subjects in the extent to which their BBF increased per unit increase in COHb. The matter of characterizing brain oxygen consumption in the face of increased COHb is possibly further complicated by reports of regional differences in responsiveness of BBF to elevated COHb. If there is an important amount of individual difference in the responsiveness of BBF and O2 extraction in the face of increased COHb, then the experimenter is faced with a much more complicated measurement problem in trying to quantify the independent variable.