EFFECT OF SMOKING ON CEREBROVASCULAR REACTIVITY

Current smoking is a risk factor for stroke, The aim of this study was to evaluate the effect of smoking one cigarette on cerebral hemodynam ics. Using transcranial Doppler ultrasound, we studied the changes of now velocity after hypercapnia in the middle cerebral arteries (MCAs) of 24 healthy young smokers and 24 healthy controls matched for age an d sex. We obtained hypercapnia with breath-holding acid evaluated cere brovascular reactivity with the breath-holding index. In smokers, the evaluation was performed during basal condition, immediately after smo king one cigarette, and at 10-, 20-, and 30-min intervals thereafter. In controls, the evaluation was performed at corresponding time interv als. Breath-holding index (BHI) values at rest were similar for both c ontrols and smokers. In the former, breath-holding index values remain ed constant for each of the different evaluations. On the contrary, in smokers, breath-holding index values were significantly lower immedia tely (p < 0.0001), at 10 min (p < 0.001), and at 20 min (p < 0.0001) a fter smoking with respect to baseline values, Smoking also caused more short-lasting changes, in this case increases in mean flow velocity ( MFV), heart rate (HR), and mean blood pressure (MBP). These results su ggest that a failure of cerebrovascular regulation occurs after smokin g. This phenomenon might contribute to the increased risk of cerebrova scular disease in current smokers.