The effect of phenylephrine on arterial and venous cerebral blood flow in healthy subjects

摘要: AIM: Sympathetic regulation of the cerebral circulation remains controversial. Although intravenous phenylephrine (PE) infusion reduces near-infrared spectroscopy (NIRS)-determined measure frontal lobe oxygenation (S(c) O(2) ) and increases middle artery mean blood velocity (MCA V(mean) ), suggesting α-adrenergic-mediated vasoconstriction, this unconfirmed by evaluation arterial venous flow. METHODS: We determined S(c) , MCA right internal carotid (ICA) jugular (IJV) flow (duplex ultrasound) during PE in eight supine young healthy men [26 (3) years, 177 (7) cm 74 (8) kg; (SD)]. RESULTS: Compared with saline, PE, pressure increased 26 ± 3% (mean SE) 4·8 1·9% (P<0·05), while decreased 13·7 3·7% (P<0·05) no significant changes oxygen or carbon dioxide tensions. ICA did not change significantly response to administration (351 12 versus 373 21 ml min(-1) ; P = 0·236), IJV (443 57 507 58 0·023). CONCLUSIONS: These findings confirm that induces a reduction measured NIRS causes an increase indicative although was preserved increased. results suggest decrease reflects altered contribution signal, we cannot rule out effect on skin is important.