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

TY - JOUR

T1 - The effect of phenylephrine on arterial and venous cerebral blood flow in healthy subjects

AU - Ogoh, Shigehiko

AU - Sato, Kohei

AU - Fisher, James P

AU - Seifert, Thomas

AU - Overgaard, Morten

AU - Secher, Niels H

N1 - © 2011 The Authors. Clinical Physiology and Functional Imaging © 2011 Scandinavian Society of Clinical Physiology and Nuclear Medicine.

PY - 2011/11

Y1 - 2011/11

N2 - Aim: Sympathetic regulation of the cerebral circulation remains controversial. Although intravenous phenylephrine (PE) infusion reduces the near-infrared spectroscopy (NIRS)-determined measure of frontal lobe oxygenation (S cO 2) and increases middle cerebral artery mean blood velocity (MCA V mean), suggesting α-adrenergic-mediated cerebral vasoconstriction, this remains unconfirmed by evaluation of arterial and venous cerebral blood flow. Methods: We determined S cO 2, MCA V mean, and right internal carotid artery (ICA) and internal jugular venous (IJV) blood flow (duplex ultrasound) during infusion of PE in eight supine young healthy men [26 (3) years, 177 (7) cm and 74 (8) kg; mean (SD)]. Results: Compared with saline, during infusion of PE, mean arterial pressure increased 26±3% (mean±SE) and MCA V mean by 4·8±1·9% (P<0·05), while S cO 2 decreased by 13·7±3·7% (P<0·05) with no significant changes in the arterial oxygen or carbon dioxide tensions. ICA blood flow did not change significantly in response to PE administration (351±12 versus 373±21mlmin -1; P=0·236), while IJV blood flow increased (443±57 versus 507±58mlmin -1; P=0·023). Conclusions: These findings confirm that PE induces a reduction in S cO 2 measured by NIRS and causes an increase in MCA V mean indicative of cerebral arterial vasoconstriction, although ICA was preserved and IJV increased. These results suggest that a decrease in S cO 2 during infusion of PE reflects an altered cerebral contribution of arterial versus venous blood to the NIRS signal, although we cannot rule out that an effect of PE on skin blood flow is important.

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

U2 - 10.1111/j.1475-097x.2011.01040.x

DO - 10.1111/j.1475-097x.2011.01040.x

M3 - Journal article

SN - 1475-0961

VL - 31

SP - 445

EP - 451

JO - Clinical Physiology and Functional Imaging

JF - Clinical Physiology and Functional Imaging

IS - 6

ER -