External carotid artery flow maintains near infrared spectroscopy-determined frontal lobe oxygenation during ephedrine administration

TY - JOUR

T1 - External carotid artery flow maintains near infrared spectroscopy-determined frontal lobe oxygenation during ephedrine administration

AU - Sørensen, H

AU - Rasmussen, P

AU - Sato, K

AU - Persson, S

AU - Olesen, N D

AU - Nielsen, H B

AU - Olsen, Niels Vidiendal

AU - Ogoh, S

AU - Secher, N H

N1 - © The Author [2014]. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: [email protected].

PY - 2014/9

Y1 - 2014/9

N2 - Background. Phenylephrine and ephedrine affect frontal lobe oxygenation (ScO2) differently when assessed by spatially resolved near infrared spectroscopy. We evaluated the effect of phenylephrine and ephedrine on extra- vs intra-cerebral blood flow and on ScO 2. Methods. In 10 healthy males (age 20-54 yr), phenylephrine or ephedrine was infused for an ~20 mm Hg increase in mean arterial pressure. Cerebral oxygenation (SavO2) was calculated from the arterial and jugular bulb oxygen saturations. Blood flow in the internal carotid artery (ICAf) and blood flow in the external carotid artery (ECAf) were assessed by duplex ultrasonography. Invos-5100c (SinvosO2) and Foresight (SforeO2) determined ScO 2 while forehead skin oxygenation (SskinO2) was assessed. Results. Phenylephrine reduced SforeO2 by 6.9% (95% confidence interval: 4.8-9.0%; P<0.0001), SinvosO2 by 10.5 (8.2-12.9%; P<0.0001), and ECAf (6-28%; P=0.0001), but increased ICAf (5-21%; P=0.003) albeit with no consequence for SskinO 2 or SavO2. In contrast, SforeO 2 was maintained with administration of ephedrine while S invosO2 and SavO2 decreased [by 3.1 (0.7-4.5%; P=0.017) and 2.1 (0.5-3.3%; P=0.012)] as arterial carbon dioxide pressure decreased (P=0.003). ICAf was stable and ECAf increased by 11 (4-18%; P=0.005) with administration of ephedrine while SskinO2 did not change. Conclusions. The effect of phenylephrine on ScO 2 is governed bya decrease in external carotid blood flow since it increases cerebral blood flow as determined by flow in the internal carotid artery. In contrast, ScO2 is largely maintained with administration of ephedrine because blood flow to extracerebral tissue increases.

AB - Background. Phenylephrine and ephedrine affect frontal lobe oxygenation (ScO2) differently when assessed by spatially resolved near infrared spectroscopy. We evaluated the effect of phenylephrine and ephedrine on extra- vs intra-cerebral blood flow and on ScO 2. Methods. In 10 healthy males (age 20-54 yr), phenylephrine or ephedrine was infused for an ~20 mm Hg increase in mean arterial pressure. Cerebral oxygenation (SavO2) was calculated from the arterial and jugular bulb oxygen saturations. Blood flow in the internal carotid artery (ICAf) and blood flow in the external carotid artery (ECAf) were assessed by duplex ultrasonography. Invos-5100c (SinvosO2) and Foresight (SforeO2) determined ScO 2 while forehead skin oxygenation (SskinO2) was assessed. Results. Phenylephrine reduced SforeO2 by 6.9% (95% confidence interval: 4.8-9.0%; P<0.0001), SinvosO2 by 10.5 (8.2-12.9%; P<0.0001), and ECAf (6-28%; P=0.0001), but increased ICAf (5-21%; P=0.003) albeit with no consequence for SskinO 2 or SavO2. In contrast, SforeO 2 was maintained with administration of ephedrine while S invosO2 and SavO2 decreased [by 3.1 (0.7-4.5%; P=0.017) and 2.1 (0.5-3.3%; P=0.012)] as arterial carbon dioxide pressure decreased (P=0.003). ICAf was stable and ECAf increased by 11 (4-18%; P=0.005) with administration of ephedrine while SskinO2 did not change. Conclusions. The effect of phenylephrine on ScO 2 is governed bya decrease in external carotid blood flow since it increases cerebral blood flow as determined by flow in the internal carotid artery. In contrast, ScO2 is largely maintained with administration of ephedrine because blood flow to extracerebral tissue increases.

KW - Adrenergic Agents

KW - Adult

KW - Carotid Artery, External

KW - Ephedrine

KW - Frontal Lobe

KW - Humans

KW - Male

KW - Middle Aged

KW - Oxygen

KW - Reference Values

KW - Spectroscopy, Near-Infrared

KW - Young Adult

U2 - 10.1093/bja/aet481

DO - 10.1093/bja/aet481

M3 - Journal article

C2 - 24508985

SN - 0007-0912

VL - 113

SP - 452

EP - 458

JO - British Journal of Anaesthesia

JF - British Journal of Anaesthesia

IS - 3

ER -