Reply to the Editor

Masahrio Ono; Kenneth Brady; Charles W. Hogue

doi:10.1016/j.jtcvs.2013.12.004

Reply to the Editor

Masahrio Ono, Kenneth Brady, Charles W. Hogue

Research output: Contribution to journal › Letter › peer-review

Original language	English (US)
Pages (from-to)	1431-1432
Number of pages	2
Journal	Journal of Thoracic and Cardiovascular Surgery
Volume	147
Issue number	4
DOIs	https://doi.org/10.1016/j.jtcvs.2013.12.004
State	Published - Apr 2014
Externally published	Yes

ASJC Scopus subject areas

Surgery
Pulmonary and Respiratory Medicine
Cardiology and Cardiovascular Medicine

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10.1016/j.jtcvs.2013.12.004

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title = "Reply to the Editor",

author = "Masahrio Ono and Kenneth Brady and Hogue, {Charles W.}",

note = "Funding Information: Dr Brassard 2 cited studies by himself and others showing that the administration of phenylephrine and norepinephrine reduced the near-infrared spectroscopy–measured regional cerebral oxygen saturation (rScO 2 ) but that this measurement was not affected by equivalent doses of ephedrine. We caution, however, in interpreting these data as an indication that the cerebral oxygen saturation has been compromised by the use of vasoconstrictors. Clinically available near-infrared spectroscopy monitors use algorithms to subtract light absorption from superficial tissue (eg, scalp, bone, pia) from deeper tissue to provide the rScO 2 measurements. 4 The importance of extracranial contamination of rScO 2 measurements has recently been highlighted in studies in which scalp ischemia induced by inflation of a circumferential cranial tourniquet affected the rScO 2 readings. 5 Whether phenylephrine or norepinephrine induces vasoconstriction of the scalp blood vessels, rather than reduces the cerebral oxygenation per se, is an explanation of the lower rScO 2 measurements when these drugs are given has not been excluded. Furthermore, whether this source of error in interpreting the rScO 2 results has clinical importance when near-infrared spectroscopy is used as a trend monitor is unclear. More importantly, the use of rScO 2 as a surrogate of cerebral blood flow for autoregulation monitoring analyzes the correlation of rScO 2 with the mean arterial pressure at the low frequencies associated with autoregulation. 6-8 These measurements are not dependent on the relative rScO 2 values but, rather, on the relationship between the changes in rScO 2 and blood pressure. Regardless, our ongoing randomized clinical trial of blood pressure management using autoregulation monitoring versus the standard of care of empiric blood pressure targets during cardiopulmonary bypass ( clinicaltrials.gov registration NCT00769691) could shed light on whether “hypotension” versus its treatment with vasoconstrictors affects patient outcomes. (Our study was funded in part by grant R01HL092259 from the National Institutes of Health to Dr Hogue.)",

year = "2014",

month = apr,

doi = "10.1016/j.jtcvs.2013.12.004",

language = "English (US)",

volume = "147",

pages = "1431--1432",

journal = "Journal of Thoracic and Cardiovascular Surgery",

issn = "0022-5223",

publisher = "Mosby Inc.",

number = "4",

}

TY - JOUR

T1 - Reply to the Editor

AU - Ono, Masahrio

AU - Brady, Kenneth

AU - Hogue, Charles W.

N1 - Funding Information: Dr Brassard 2 cited studies by himself and others showing that the administration of phenylephrine and norepinephrine reduced the near-infrared spectroscopy–measured regional cerebral oxygen saturation (rScO 2 ) but that this measurement was not affected by equivalent doses of ephedrine. We caution, however, in interpreting these data as an indication that the cerebral oxygen saturation has been compromised by the use of vasoconstrictors. Clinically available near-infrared spectroscopy monitors use algorithms to subtract light absorption from superficial tissue (eg, scalp, bone, pia) from deeper tissue to provide the rScO 2 measurements. 4 The importance of extracranial contamination of rScO 2 measurements has recently been highlighted in studies in which scalp ischemia induced by inflation of a circumferential cranial tourniquet affected the rScO 2 readings. 5 Whether phenylephrine or norepinephrine induces vasoconstriction of the scalp blood vessels, rather than reduces the cerebral oxygenation per se, is an explanation of the lower rScO 2 measurements when these drugs are given has not been excluded. Furthermore, whether this source of error in interpreting the rScO 2 results has clinical importance when near-infrared spectroscopy is used as a trend monitor is unclear. More importantly, the use of rScO 2 as a surrogate of cerebral blood flow for autoregulation monitoring analyzes the correlation of rScO 2 with the mean arterial pressure at the low frequencies associated with autoregulation. 6-8 These measurements are not dependent on the relative rScO 2 values but, rather, on the relationship between the changes in rScO 2 and blood pressure. Regardless, our ongoing randomized clinical trial of blood pressure management using autoregulation monitoring versus the standard of care of empiric blood pressure targets during cardiopulmonary bypass ( clinicaltrials.gov registration NCT00769691) could shed light on whether “hypotension” versus its treatment with vasoconstrictors affects patient outcomes. (Our study was funded in part by grant R01HL092259 from the National Institutes of Health to Dr Hogue.)

PY - 2014/4

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JO - Journal of Thoracic and Cardiovascular Surgery

JF - Journal of Thoracic and Cardiovascular Surgery

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Reply to the Editor

ASJC Scopus subject areas

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