The Influence of Tobacco Smoking Intensity on Hemodynamic Parameters: A Functional Transcranial Doppler Study on Vascular Reserve in Chronic Smokers.

OBJECTIVE

Tobacco smoking is an independent risk factor for stroke. In acute and chronic settings, it affects cerebral blood flow, mean systolic velocities, changes of velocities in response to metabolic challenges, pulsatility, and resistance indices in otherwise healthy smokers. The objective of the study was to determine the influence of smoking intensity on hemodynamic parameters in nonsmokers and smokers.

METHODS

This prospective study enrolled 34 healthy volunteers, 19 smokers and 15 nonsmokers. Epidemiological data were taken from all patients, and exhaled carbon monoxide concentration was measured in smokers. To obtain hemodynamic parameters, we performed functional transcranial Doppler (fTCD) recordings on the posterior cerebral artery for six minutes, consisting of three cycles with closed and opened eyes. We investigated mean systolic velocities, neurovascular responses, and pulsatility indices.

RESULTS

Smokers had significantly lower blood flow velocities than nonsmokers (28.36±5.87 and 30.19±6.41, respectively). Neurovascular response as a marker of vasodilatory potential was significantly lower in smokers (14.27%±0.08%) than in the nonsmoker group (17.33%±0.06%). Smokers with higher exhaled carbon monoxide concentrations had lower blood flow velocities than those with lower CO concentrations. Smokers had higher levels of pulsatility indices compared to nonsmokers.

CONCLUSION

The vasodilatory mechanism of cerebral blood vessels is impaired in chronic, otherwise healthy smokers.