Effects of Smoking on Cerebral Circulation A TCD Study

Abstract In 20 healthy subjects the right middle cerebral artery TCD Doppler shift was monitored over 10 minutes and on-line analyzed. During minutes 3, 4 and 5 the subjects smoked a cigarette of their choice making a deep inhalation every 20 seconds and respiring normally in between. Blood pressure and heart rate were externally measured every 30 seconds. Cigarette smoking significantly increased blood pressure, heart rate and flow velocity. The TCD pulsatility index increased only after smoking. Flow velocity dropped to an average of 94 + / -8% over postsmoking minutes 4 and 5. Repeated smoking spaced by several days done only in 1 subject so far having the middle cerebral artery Doppler signal recorded and analyzed bilaterally resulted in increased flow after smoking on one side and in decreased flow on the other. In conclusion the increase in heart rate and blood pressure and results indicate dilation of the cerebral resistance arteries during smoking followed by constriction of these vessels. The vasculature of one individual hemisphere may react differently on repeated smoking.