Relationship between Cardiopulmonary Bypass Flow Rate and Cerebral Embolization in Dogs

Background Cerebral embolization is a primary cause of cardiac surgical neurologic morbidity. During cardiopulmonary bypass (CPB), there are well-defined periods of embolic risk. In theory, cerebral embolization might be reduced by an increase in pump flow during these periods. The purpose of this study was to determine the CPB flow-embolization relation in a canine model. Methods Twenty mongrel dogs underwent CPB at 35 degrees C with alpha-stat management and a fentanyl-midazolam anesthetic. In each animal, CPB flow was adjusted to achieve a mean arterial pressure of 65-75 mmHg. During CPB, an embolic load of 1.2 x 10(5) 67 microm fluorescent microspheres was injected into the arterial inflow line. Before and after embolization, cerebral blood flow was determined using 15-microm microspheres. Tissue was taken from 12 brain regions and microspheres were recovered. The relation between pump flow and embolization/g of brain was determined. Results The mean arterial pressure at embolization was 67 +/-4 mmHg, and the range of pump flow was 0.9-3.5 l x min(-1)x m(-2). Cerebral blood flow was independent of pump flow. At lower pump flow, the percentage of that flow delivered to the brain increased. There was a strong inverse relation between pump flow and cerebral embolization (r = -0.708, P < 0.000 by Spearman rank order correlation). Conclusions Cerebral embolization is determined by the CPB flow. At an unchanged mean arterial pressure, as pump flow is reduced, a progressively greater proportion of that flow is delivered to the brain.

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CARDIOPULMONARY BYPASS (CPB) PUMP FLOW DOES NOT AFFECT CEREBRAL BLOOD FLOW (CBF) INDEPENDENT OF ITS EFFECT ON MEAN ARTERIAL PRESSURE (MAP) IN DOGS

Anesthesia & Analgesia ◽

10.1097/00000539-199902001-00103 ◽

1999 ◽

Vol 88 (Supplement) ◽

pp. 103S

Author(s):

H. Sungurtekin ◽

U. Boston ◽

D.J. Cook

Keyword(s):

Blood Flow ◽

Cerebral Blood Flow ◽

Cardiopulmonary Bypass ◽

Mean Arterial Pressure ◽

Arterial Pressure ◽

Pump Flow

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EFFECT OF HEMATOCRIT ON MEAN ARTERIAL PRESSURE AND CEREBRAL BLOOD FLOW DURING CARDIOPULMONARY BYPASS

Anesthesiology ◽

10.1097/00000542-198909001-00042 ◽

1989 ◽

Vol 71 (Supplement) ◽

pp. A42

Author(s):

R C Roy ◽

D S Prough ◽

D A Stump ◽

A T Rogers ◽

J Phipps

Keyword(s):

Blood Flow ◽

Cerebral Blood Flow ◽

Cardiopulmonary Bypass ◽

Mean Arterial Pressure ◽

Arterial Pressure

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Tailoring cardiopulmonary bypass pump flow and mean arterial pressure to maintain renal oxygenation

Acta Physiologica ◽

10.1111/apha.13619 ◽

2021 ◽

Vol 231 (4) ◽

Author(s):

Jaap A. Joles

Keyword(s):

Cardiopulmonary Bypass ◽

Mean Arterial Pressure ◽

Arterial Pressure ◽

Pump Flow

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Direct Cerebral Vasodilatory Effects of Sevoflurane and Isoflurane

Anesthesiology ◽

10.1097/00000542-199909000-00019 ◽

1999 ◽

Vol 91 (3) ◽

pp. 677-677 ◽

Cited By ~ 236

Author(s):

Basil F. Matta ◽

Karen J. Heath ◽

Kate Tipping ◽

Andrew C. Summors

Keyword(s):

Blood Pressure ◽

Blood Flow ◽

Cerebral Blood Flow ◽

Mean Arterial Pressure ◽

Arterial Pressure ◽

Middle Cerebral Artery ◽

Flow Velocity ◽

Cerebral Artery ◽

Blood Flow Velocity ◽

End Tidal

Background The effect of volatile anesthetics on cerebral blood flow depends on the balance between the indirect vasoconstrictive action secondary to flow-metabolism coupling and the agent's intrinsic vasodilatory action. This study compared the direct cerebral vasodilatory actions of 0.5 and 1.5 minimum alveolar concentration (MAC) sevoflurane and isoflurane during an propofol-induced isoelectric electroencephalogram. Methods Twenty patients aged 20-62 yr with American Society of Anesthesiologists physical status I or II requiring general anesthesia for routine spinal surgery were recruited. In addition to routine monitoring, a transcranial Doppler ultrasound was used to measure blood flow velocity in the middle cerebral artery, and an electroencephalograph to measure brain electrical activity. Anesthesia was induced with propofol 2.5 mg/kg, fentanyl 2 micro/g/kg, and atracurium 0.5 mg/kg, and a propofol infusion was used to achieve electroencephalographic isoelectricity. End-tidal carbon dioxide, blood pressure, and temperature were maintained constant throughout the study period. Cerebral blood flow velocity, mean blood pressure, and heart rate were recorded after 20 min of isoelectric encephalogram. Patients were then assigned to receive either age-adjusted 0.5 MAC (0.8-1%) or 1.5 MAC (2.4-3%) end-tidal sevoflurane; or age-adjusted 0.5 MAC (0.5-0.7%) or 1.5 MAC (1.5-2%) end-tidal isoflurane. After 15 min of unchanged end-tidal concentration, the variables were measured again. The concentration of the inhalational agent was increased or decreased as appropriate, and all measurements were repeated again. All measurements were performed before the start of surgery. An infusion of 0.01% phenylephrine was used as necessary to maintain mean arterial pressure at baseline levels. Results Although both agents increased blood flow velocity in the middle cerebral artery at 0.5 and 1.5 MAC, this increase was significantly less during sevoflurane anesthesia (4+/-3 and 17+/-3% at 0.5 and 1.5 MAC sevoflurane; 19+/-3 and 72+/-9% at 0.5 and 1.5 MAC isoflurane [mean +/- SD]; P<0.05). All patients required phenylephrine (100-300 microg) to maintain mean arterial pressure within 20% of baseline during 1.5 MAC anesthesia. Conclusions In common with other volatile anesthetic agents, sevoflurane has an intrinsic dose-dependent cerebral vasodilatory effect. However, this effect is less than that of isoflurane.

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Cerebral blood flow and energy metabolism during stress

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1990.259.2.h269 ◽

1990 ◽

Vol 259 (2) ◽

pp. H269-H280 ◽

Cited By ~ 10

Author(s):

R. M. Bryan

Keyword(s):

Blood Flow ◽

Cerebral Blood Flow ◽

Energy Metabolism ◽

Adrenergic Receptor ◽

Conditioned Fear ◽

Brain Regions ◽

Stressful Events ◽

Ethanol Withdrawal ◽

Adrenergic Mechanism ◽

The Brain

Many, but not all, stressful events are accompanied by increases in cerebral blood flow and/or energy metabolism. The stressful events include pharmacological paralysis, footshock, conditioned fear, hypotension, hypoglycemia, hypoxia, noise, and ethanol withdrawal. These increases are significant because 1) all brain regions are often affected, i.e., certain stressful events have global effects on cerebral blood flow and energy metabolism; and 2) various stressful events appear to have a common adrenergic mechanism for increasing cerebral blood flow and energy metabolism. The adrenergic mechanism involves beta-adrenergic receptor stimulation by either epinephrine secreted from the adrenal medulla or possibly norepinephrine endogenous to the brain. While adrenergic mechanisms are not the only mechanism controlling flow and metabolism for a given stressful condition, they do appear to be common to many situations. At least part of the increase in cerebral blood flow and energy metabolism during many conditions appears to be the result of the stress response and not directly a result of the condition itself.

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Cerebrovascular effects of hypocapnia during adenosine-induced arterial hypotension

Journal of Neurosurgery ◽

10.3171/jns.1985.63.6.0937 ◽

1985 ◽

Vol 63 (6) ◽

pp. 937-943 ◽

Cited By ~ 7

Author(s):

David J. Boarini ◽

Neal F. Kassell ◽

James A. Sprowell ◽

Julie J. Olin ◽

Hans C. Coester

Keyword(s):

Blood Flow ◽

Cerebral Blood Flow ◽

Mean Arterial Pressure ◽

Arterial Pressure ◽

Arterial Hypotension ◽

Content Type ◽

Blood Flows ◽

Before And After ◽

Regional Blood Flows ◽

Fine Print

✓ Profound arterial hypotension is à commonly used adjunct in surgery for aneurysms and arteriovenous malformations. Hyperventilation with hypocapnia is also used in these patients to increase brain slackness. Both measures reduce cerebral blood flow (CBF). Of concern is whether CBF is reduced below ischemic thresholds when both techniques are employed together. To determine this, 12 mongrel dogs were anesthetized with morphine, nitrous oxide, and oxygen, and then paralyzed with pancuronium and hyperventilated. Arterial pCO2 was controlled by adding CO2 to the inspired gas mixture. Cerebral blood flow was measured at arterial pCO2 levels of 40 and 20 mm Hg both before and after mean arterial pressure was lowered to 40 mm Hg with adenosine enhanced by dipyridamole. In animals where PaCO2 was reduced to 20 mm Hg and mean arterial pressure was reduced to 40 mm Hg, cardiac index decreased 42% from control and total brain blood flow decreased 45% from control while the cerebral metabolic rate of oxygen was unchanged. Hypocapnia with hypotension resulted in small but statistically significant reductions in all regional blood flows, most notably in the brain stem. The reported effects of hypocapnia on CBF during arterial hypotension vary depending on the hypotensive agents used. Profound hypotension induced with adenosine does not eliminate CO2 reactivity, nor does it lower blood flow to ischemic levels in this model, even in the presence of severe hypocapnia.

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Impact of blood pressure changes in cerebral blood perfusion of patients with ischemic Moyamoya disease evaluated by SPECT

Journal of Cerebral Blood Flow & Metabolism ◽

10.1177/0271678x20967458 ◽

2020 ◽

pp. 0271678X2096745

Author(s):

Zhao Liming ◽

Sun Weiliang ◽

Jia Jia ◽

Liang Hao ◽

Liu Yang ◽

...

Keyword(s):

Blood Pressure ◽

Blood Flow ◽

Cerebral Blood Flow ◽

Mean Arterial Pressure ◽

Arterial Pressure ◽

Moyamoya Disease ◽

Emission Computed Tomography ◽

Study Cohort ◽

Pressure Changes ◽

The Impact

Our aim was to determine the impact of targeted blood pressure modifications on cerebral blood flow in ischemic moyamoya disease patients assessed by single-photon emission computed tomography (SPECT). From March to September 2018, we prospectively collected data of 154 moyamoya disease patients and selected 40 patients with ischemic moyamoya disease. All patients underwent in-hospital blood pressure monitoring to determine the mean arterial pressure baseline values. The study cohort was subdivided into two subgroups: (1) Group A or relative high blood pressure (RHBP) with an induced mean arterial pressure 10–20% higher than baseline and (2) Group B or relative low blood pressure (RLBP) including patients with mean arterial pressure 10–20% lower than baseline. All patients underwent initial SPECT study on admission-day, and on the following day, every subgroup underwent a second SPECT study under their respective targeted blood pressure values. In general, RHBP patients showed an increment in perfusion of 10.13% (SD 2.94%), whereas RLBP patients showed a reduction of perfusion of 12.19% (SD 2.68%). Cerebral blood flow of moyamoya disease patients is susceptible to small blood pressure changes, and cerebral autoregulation might be affected due to short dynamic blood pressure modifications.

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