Phenylephrine Increases Cerebral Blood Flow during Low-flow Hypothermic Cardiopulmonary Bypass in Baboons

Schwartz, Arthur E.; Minanov, Oktavijan P.; Stone, Gilbert J.; Adams, David C.; Sandhu, Aqeel A.; Pearson, Mark E.; Kwiatkowski, Paweł; Young, William L.; Michler, Robert E.

doi:10.1097/00000542-199608000-00020

Cited by 25 publications

(8 citation statements)

References 19 publications

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“…Although the kidneys make up only 2% of body mass, they receive almost 25% of cardiac output (4). Our data support a model in which the brain is perfusion-pressure dependent, whereas the kidney is more dependent on cardiac output (17). The vasoactive neurohormonal axes activated by circulatory compromise, including sympathetic tone increase, activation of the renin-angiotensin cascade, and release of vasopressin, cause profound reductions in RBF while ABP is preserved.…”

Section: Discussionsupporting

confidence: 72%

Renovascular reactivity measured by near-infrared spectroscopy

Rhee

Kibler

Easley

et al. 2012

Journal of Applied Physiology

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Hypotension and shock are risk factors for death, renal insufficiency, and stroke in preterm neonates. Goal-directed neonatal hemodynamic management lacks end-organ monitoring strategies to assess the adequacy of perfusion. Our aim is to develop a clinically viable, continuous metric of renovascular reactivity to gauge renal perfusion during shock. We present the renovascular reactivity index (RVx), which quantifies passivity of renal blood volume to spontaneous changes in arterial blood pressure. We tested the ability of the RVx to detect reductions in renal blood flow. Hemorrhagic shock was induced in 10 piglets. The RVx was monitored as a correlation between slow waves of arterial blood pressure and relative total hemoglobin (rTHb) obtained with reflectance near-infrared spectroscopy (NIRS) over the kidney. The RVx was compared with laser-Doppler measurements of red blood cell flux, and renal laser-Doppler measurements were compared with cerebral laser-Doppler measurements. Renal blood flow decreased to 75%, 50%, and 25% of baseline at perfusion pressures of 60, 45, and 40 mmHg, respectively, whereas in the brain these decrements occurred at pressures of 30, 25, and 15 mmHg, respectively. The RVx compared favorably to the renal laser-Doppler data. Areas under the receiver operator characteristic curves using renal blood flow thresholds of 50% and 25% of baseline were 0.85 (95% CI, 0.83-0.87) and 0.90 (95% CI, 0.88-0.92). Renovascular autoregulation can be monitored and is impaired in advance of cerebrovascular autoregulation during hemorrhagic shock.

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Section: Discussionsupporting

confidence: 72%

Renovascular reactivity measured by near-infrared spectroscopy

Rhee

Kibler

Easley

et al. 2012

Journal of Applied Physiology

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“…These and other data support the notion that cerebral blood flow is more dependent on blood pressure during cardiac surgery while renal blood flow maybe more dependent on cardiac output or CPB flow rate. 65,66 …”

Section: Discussionmentioning

confidence: 99%

Cerebral Near-Infrared Spectroscopy Monitoring and Neurologic Outcomes in Adult Cardiac Surgery Patients

Zheng

Sheinberg

Yee

et al. 2013

Anesthesia &Amp; Analgesia

259

130

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Background Near-infrared spectroscopy is used during cardiac surgery to monitor the adequacy of cerebral perfusion. In this systematic review, we evaluated available data for adult patients to determine (1) whether decrements in cerebral oximetry during cardiac surgery are associated with stroke, postoperative cognitive dysfunction (POCD), or delirium and (2) whether interventions aimed at correcting cerebral oximetry decrements improve neurologic outcomes. Methods We searched PubMed, Cochrane, and Embase databases from inception until January 31, 2012, without restriction on languages. Each article was examined for additional references. A publication was excluded if it did not include original data (e.g., review, commentary) or if it was not published as a full-length article in a peer-reviewed journal (e.g., abstract only). The identified abstracts were screened first, and full texts of eligible papers were reviewed independently by two investigators. For eligible publications, we recorded the number of subjects, type of surgery, and criteria for diagnosis of neurologic endpoints. Results We identified 13 case reports, 27 observational studies, and two prospectively randomized intervention trials that met our inclusion criteria. Case reports and two observational studies contained anecdotal evidence suggesting that regional cerebral O2 saturation (rScO2) monitoring could be used to identify cardiopulmonary bypass (CPB) cannula malposition. Six of nine observational studies reported an association between acute rScO2 desaturation and POCD based on the Mini-Mental Status Examination (n=3 studies) or more detailed cognitive testing (n=6 studies). Two retrospective studies reported a relationship between rScO2 desaturation and stroke or type I and II neurologic injury after surgery. The observational studies had many limitations, including small sample size, assessments only during the immediate postoperative period, and failure to perform risk adjustments. Two randomized studies evaluated the efficacy of interventions for treating rScO2 desaturation during surgery, but adherence to the protocol was poor in one. In the other study, interventions for rScO2 desaturation were associated with less major organ injury and shorter intensive care unit hospitalization compared with nonintervention. Conclusions Reductions in rScO2 during cardiac surgery may identify CPB cannula malposition, particularly during aortic surgery. Only low-level evidence links low rScO2 during cardiac surgery to postoperative neurologic complications, and data are insufficient to conclude that interventions to improve rScO2 desaturation prevent stroke or POCD.

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“…Although phenylephrine increases cerebral vascular tone in humans, it can increase [38] or has no influence [39] on cerebral vascular resistance. The use of phenylephrine increases CBF in cardiopulmonary bypass patients [40], healthy subjects [38], and anesthetized patients [41]. However, in other situations, CBF seems unaffected by phenylephrine [6].…”

Section: Discussionmentioning

confidence: 99%

Phenylephrine but not Ephedrine Reduces Frontal Lobe Oxygenation Following Anesthesia-Induced Hypotension

et al. 2009

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Phenylephrine Increases Cerebral Blood Flow during Low-flow Hypothermic Cardiopulmonary Bypass in Baboons

Abstract: Although low-flow CPB resulted in a marked decrease in CBF compared with prebypass and full-flow bypass, phenylephrine administered to double arterial pressure during low-flow bypass produced a proportional increase in CBF.

Cited by 25 publications

References 19 publications

Renovascular reactivity measured by near-infrared spectroscopy

Renovascular reactivity measured by near-infrared spectroscopy

Cerebral Near-Infrared Spectroscopy Monitoring and Neurologic Outcomes in Adult Cardiac Surgery Patients

Phenylephrine but not Ephedrine Reduces Frontal Lobe Oxygenation Following Anesthesia-Induced Hypotension

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