Sustained Visual Attention and Carbon Monoxide: Elimination of Adaptation Effects

Abstract

Eighteen subjects performed a 1-h visual vigilance task, once during a control condition (filtered air) and once during an experimental condition (CO). The COHb level was elevated to 5% utilizing a bolus maintenance technique which raised the COHb level rapidly so that there would be no possibility of an adaptation occurring prior to vigilance testing. Physiological measurements included heart rate, blood pressure, and ventilation. Neither vigilance performance nor the physiological variables was statistically affected by the 5% COHb level. Subjects identified a significantly (p> 0.05) higher percentage of signals with the high frequency of signal presentation as compared to the low frequency under both filtered air and the 5% COHb level. Signal detection improved in 12 subjects during minutes 0-15, while 10 subjects showed improvement during minutes 31-45 with an elevated COHb level. The subjective questionnaire indicated that CO significantly (p < 0.01) decreased the subjects' confidence concerning their performance on the vigilance task, as well as causing significant (p < 0.05) irritation of the eyes and throat.