Acute carbon monoxide exposure and cerebral blood flow in rabbits

Carbon monoxide (CO) 1% was administered to anaesthetised rabbits for 15 minutes. Despite a 28% +/- 5.8 (SEM) fall in mean arterial blood pressure during the CO exposure, cerebral blood flow increased by 236% +/- 36.5 in the left and 287% +/- 28.9 in the right cortex. Cerebrovascular resistance was reduced by 70.6% +/- 2.8 in the left and by 76.2% +/- 3 in the right cortex. These changes were accompanied by an increase in intracranial pressure, a drop in body temperature and ventilation requirement, and a metabolic acidosis. When the CO was withdrawn all these parameters returned to normal over three hours. Hence, these vascular effects are reversible and consistent with the natural history of CO intoxication in humans. Carboxyhaemoglobin levels correlated well with hemispheric cerebral blood flow (r = 0.90; r = 0.98) and cerebrovascular resistance (r = 0.87; r = 0.97).