TY - JOUR

T1 - Ultrasound tagged near infrared spectroscopy does not detect hyperventilation-induced reduction in cerebral blood flow

AU - Lund, Anton

AU - Secher, Niels H.

AU - Hirasawa, Ai

AU - Ogoh, Shigehiko

AU - Hashimoto, Takeshi

AU - Schytz, Henrik W

AU - Ashina, Messoud

AU - Sørensen, Henrik

PY - 2016

Y1 - 2016

N2 - Introduction: Continuous non-invasive monitoring of cerebral blood flow (CBF) may be important during anaesthesia and several options are available. We evaluated the CerOx monitor that employs ultrasound tagged near infrared spectroscopy to estimate changes in a CBF index (CFI).Methods: Seven healthy males (age 21-26 years) hyperventilated and were administered phenylephrine to increase mean arterial pressure by 20-30 mmHg. Frontal lobe tissue oxygenation (ScO2) and CFI were obtained using the CerOx and mean blood flow velocity in the middle cerebral artery (MCAvmean) was determined by transcranial Doppler. Blood flow in the internal and external carotid artery (ICAf and ECAf) was determined using duplex ultrasonography and forehead skin blood flow (SkBF) and oxygenation (SskinO2) by laser Doppler and white light spectroscopy.Results: During hyperventilation MCAvmean and ICAf decreased by 44% (median; interquartile range 40-49; p = 0.016) and 46% (40-53; p = 0.03), respectively. Conversely, CFI increased by 9% (2-31; p = 0.016), while no significant change was observed in ScO2. SkBF increased by 19% (9-53; p = 0.016) and SskinO2 by 6% (1-7; p = 0.047), although ECAf was unchanged. Administration of phenylephrine was not associated with any changes in MCAvmean, ICAf, ECAf, ScO2, SkBF, SskinO2, or CFI.Conclusion: The CerOx was able to detect a stable CBF during administration of phenylephrine. However, during hyperventilation MCAvmean and ICAf decreased while CFI increased, likely due to an increase in superficial tissue oxygenation. Thus, CFI does not provide an unbiased evaluation of changes in CBF.

AB - Introduction: Continuous non-invasive monitoring of cerebral blood flow (CBF) may be important during anaesthesia and several options are available. We evaluated the CerOx monitor that employs ultrasound tagged near infrared spectroscopy to estimate changes in a CBF index (CFI).Methods: Seven healthy males (age 21-26 years) hyperventilated and were administered phenylephrine to increase mean arterial pressure by 20-30 mmHg. Frontal lobe tissue oxygenation (ScO2) and CFI were obtained using the CerOx and mean blood flow velocity in the middle cerebral artery (MCAvmean) was determined by transcranial Doppler. Blood flow in the internal and external carotid artery (ICAf and ECAf) was determined using duplex ultrasonography and forehead skin blood flow (SkBF) and oxygenation (SskinO2) by laser Doppler and white light spectroscopy.Results: During hyperventilation MCAvmean and ICAf decreased by 44% (median; interquartile range 40-49; p = 0.016) and 46% (40-53; p = 0.03), respectively. Conversely, CFI increased by 9% (2-31; p = 0.016), while no significant change was observed in ScO2. SkBF increased by 19% (9-53; p = 0.016) and SskinO2 by 6% (1-7; p = 0.047), although ECAf was unchanged. Administration of phenylephrine was not associated with any changes in MCAvmean, ICAf, ECAf, ScO2, SkBF, SskinO2, or CFI.Conclusion: The CerOx was able to detect a stable CBF during administration of phenylephrine. However, during hyperventilation MCAvmean and ICAf decreased while CFI increased, likely due to an increase in superficial tissue oxygenation. Thus, CFI does not provide an unbiased evaluation of changes in CBF.

KW - Cerebral oximetry

KW - external carotid artery

KW - internal carotid artery

KW - monitoring

KW - skin blood flow

KW - skin oxygen saturation

U2 - 10.3109/00365513.2015.1101485

DO - 10.3109/00365513.2015.1101485

M3 - Journal article

C2 - 26503121

AN - SCOPUS:84947866862

VL - 76

SP - 82

EP - 87

JO - Scandinavian Journal of Clinical & Laboratory Investigation

JF - Scandinavian Journal of Clinical & Laboratory Investigation

SN - 0036-5513

IS - 1

ER -