TY - JOUR
T1 - A Decrease in Spatially Resolved Near-Infrared Spectroscopy-Determined Frontal Lobe Tissue Oxygenation by Phenylephrine Reflects Reduced Skin Blood Flow
AU - Ogoh, Shigehiko
AU - Sato, Kohei
AU - Okazaki, Kazunobu
AU - Miyamoto, Tadayoshi
AU - Secher, Frederik
AU - Sørensen, Henrik
AU - Rasmussen, Peter
AU - Secher, Niels H.
PY - 2014/4
Y1 - 2014/4
N2 - BACKGROUND: Spatially resolved near-infrared spectroscopy-determined frontal lobe tissue oxygenation (Sco2) is reduced with administration of phenylephrine, while cerebral blood flow may remain unaffected. We hypothesized that extracranial vasoconstriction explains the effect of phenylephrine on Sco2. METHODS: We measured Sco2 and internal and external carotid as well as vertebral artery blood flow in 7 volunteers (25 [SD 4] years) by duplex ultrasonography during IV infusion of phenylephrine, together with middle cerebral artery mean blood velocity, forehead skin blood flow, and mean arterial blood pressure. RESULTS: During phenylephrine infusion, mean arterial blood pressure increased, while Sco 2 decreased by -19% ± 3% (mean ± SE; P = 0.0005). External carotid artery (-27.5% ± 3.0%) and skin blood flow (-25.4% ± 7.8%) decreased in response to phenylephrine administration, and there was a relationship between Sco2 and forehead skin blood flow (Pearson r = 0.55, P = 0.042, 95% confidence interval [CI], = 0.025-0.84; Spearman r = 0.81, P < 0.001, 95% CI, 0.49-0.94) and external carotid artery conductance (Pearson r = 0.62, P = 0.019, 95% CI, 0.13 to 0.86; Spearman r = 0.64, P = 0.012, 95% CI, 0.17-0.88). CONCLUSIONS: These findings suggest that a phenylephrine-induced decrease in Sco2, as determined by INVOS-4100 near-infrared spectroscopy, reflects vasoconstriction in the extracranial vasculature rather than a decrease in cerebral oxygenation.
AB - BACKGROUND: Spatially resolved near-infrared spectroscopy-determined frontal lobe tissue oxygenation (Sco2) is reduced with administration of phenylephrine, while cerebral blood flow may remain unaffected. We hypothesized that extracranial vasoconstriction explains the effect of phenylephrine on Sco2. METHODS: We measured Sco2 and internal and external carotid as well as vertebral artery blood flow in 7 volunteers (25 [SD 4] years) by duplex ultrasonography during IV infusion of phenylephrine, together with middle cerebral artery mean blood velocity, forehead skin blood flow, and mean arterial blood pressure. RESULTS: During phenylephrine infusion, mean arterial blood pressure increased, while Sco 2 decreased by -19% ± 3% (mean ± SE; P = 0.0005). External carotid artery (-27.5% ± 3.0%) and skin blood flow (-25.4% ± 7.8%) decreased in response to phenylephrine administration, and there was a relationship between Sco2 and forehead skin blood flow (Pearson r = 0.55, P = 0.042, 95% confidence interval [CI], = 0.025-0.84; Spearman r = 0.81, P < 0.001, 95% CI, 0.49-0.94) and external carotid artery conductance (Pearson r = 0.62, P = 0.019, 95% CI, 0.13 to 0.86; Spearman r = 0.64, P = 0.012, 95% CI, 0.17-0.88). CONCLUSIONS: These findings suggest that a phenylephrine-induced decrease in Sco2, as determined by INVOS-4100 near-infrared spectroscopy, reflects vasoconstriction in the extracranial vasculature rather than a decrease in cerebral oxygenation.
KW - Algorithms
KW - Blood Pressure
KW - Carotid Artery, External
KW - Frontal Lobe
KW - Heart Rate
KW - Humans
KW - Linear Models
KW - Male
KW - Middle Cerebral Artery
KW - Oxygen Consumption
KW - Phenylephrine
KW - Regional Blood Flow
KW - Skin
KW - Spectroscopy, Near-Infrared
KW - Vascular Resistance
KW - Vasoconstrictor Agents
KW - Vertebral Artery
KW - Young Adult
U2 - 10.1213/ane.0000000000000145
DO - 10.1213/ane.0000000000000145
M3 - Journal article
C2 - 24651237
SN - 0003-2999
VL - 118
SP - 823
EP - 829
JO - Anesthesia and Analgesia
JF - Anesthesia and Analgesia
IS - 4
ER -