Abstract 9344: Tobacco Smoke Exposure is Associated with Alterations of Cerebrovascular Flow Velocities and Regulation in Children

Abstract

Background: Passive smoking (PS) is associated with increased risk for cerebrovascular and cardiovascular events, however, there has been little focus on cerebrovascular function. The purpose of this study is to assess cerebrovascular flow velocities and regulation in PS children. Methods: Noninvasive ultrasonographic measurements were made in 51 children (age:9 ± 4years) who have been exposed to tobacco smoking since intrauterine life and 35 age-matched children without PS. Using transcranial color Doppler sonography, peak systolic (PSV), end-diastolic (EDV), and average peak flow (APV) velocities of middle cerebral artery were measured during supine rest and 3 minutes-upright posture. Pulsatile index as a parameter of vascular resistance was calculated. Pulsatile index was defined as (PSV-EDV)/APV. Quantitative B-mode ultrasound scans were used to measure intima-media thickness and diameters of the common carotid artery. Urine cotinine concentrations were assessed. Results: Flow velocities and pulsatile index were not significantly different between controls and PS children (p > 0.05). In controls and PS children with urine cotinine concentrations <5ng/ml (n = 26), pulsatile index did not change during upright position (p > 0.05). However, in PS children with urine cotinine concentrations ≥ 5ng/ml (n = 25), there was a significant increase in pulsatile index during upright position (0.93 ± 0.14 vs. 0.87 ± 0.12, p < 0.01), because APV and EDV were significantly lower (69 ± 16 vs. 76 ±17 cm/sec and 44 ± 9 vs. 50 ± 11 cm/sec, p <0.05, respectively), although PSV was not significantly different. The percent change in pulsatile index during an upright position correlated significantly with urine cotinine level (r =0.57, p < 0.01). Intima-media thickness at carotid artery and stiffness did not correlate with cerebral blood flow velocities. Conclusions: The present study indicates that passive smoking can adversely affect cerebral blood flow and regulation in the cerebrovascular bed in childhood. Passive smoking not only is a risk factor for later cardiovascular disease, but also is associated with significant impairment of cerebral flow dynamics.