The Impact of Inotropes and Vasopressors on Cerebral Oxygenation in Patients with Traumatic Brain Injury and Subarachnoid Hemorrhage: A Narrative Review

Brain Sciences, Journal Year: 2024, Volume and Issue: 14(2), P. 117 - 117

Published: Jan. 24, 2024

Traumatic brain injury (TBI) and subarachnoid hemorrhage (SAH) are critical neurological conditions that necessitate specialized care in the Intensive Care Unit (ICU). Managing cerebral perfusion pressure (CPP) mean arterial (MAP) is of primary importance these patients. To maintain targeted MAP CPP, vasopressors and/or inotropes commonly used. However, their effects on oxygenation not fully understood. The aim this review to provide an up-to date regarding current uses pathophysiological issues related use TBI SAH According our findings, despite achieving similar hemodynamic parameters various oxygenation, local CBF metabolism heterogeneous. Therefore, a more accurate understanding activity medications crucial for optimizing patient management ICU setting.

Language: Английский

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Acid–base balance and cerebrovascular regulation

The Journal of Physiology, Journal Year: 2021, Volume and Issue: 599(24), P. 5337 - 5359

Published: Oct. 27, 2021

The regulation and defence of intracellular pH is essential for homeostasis. Indeed, alterations in cerebrovascular acid-base balance directly affect cerebral blood flow (CBF) which has implications human health disease. For example, changes CBF during disturbances are evident conditions such as chronic obstructive pulmonary disease diabetic ketoacidosis. classic experimental studies from the past 75+ years utilized to describe integrative relationships between CBF, carbon dioxide tension (PCO2 ), bicarbonate (HCO3- ) pH. These factors interact influence (1) time course compensatory respective responses (due rapid exchange kinetics arterial blood, extracellular fluid brain tissue). We propose that [HCO3- ] acute respiratory acidosis/alkalosis contribute regulation; (2) by direct vs. extravascular/interstitial PCO2 - latter recognized proximal compartment alters vascular smooth muscle cell CBF. Taken together, these results substantiate two key ideas: first, affected severity metabolic/respiratory disturbances, including extent partial/full compensation; second, independent diffusion CO2 across blood-brain barrier integral altering perivascular Overall, realizing , HCO3- pH, may provide insights improve clinical practice with treatment systemic disorders.

Language: Английский

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Cerebrovascular Reactivity: Purpose, Optimizing Methods, and Limitations to Interpretation – A Personal 20-Year Odyssey of (Re)searching

Frontiers in Physiology, Journal Year: 2021, Volume and Issue: 12

Published: April 1, 2021

The brain is a neurovascular organ. A stimulus-response approach effective in interrogating the physiology of its vasculature. Ideally, stimulus standardized across patients, and single patient over time. We developed standard attempted to measure, classify, interpret many forms responses. Over past 20 years, our work has delivered nuanced insights into normal cerebral vascular physiology, as well adaptive physiological responses presence disease. trajectory understanding did not follow logical linear progression; rather, it emerged coalescence new, old, previously dismissed, ideas that had accumulated In this essay, we review what believe were most valuable – sometimes controversial during two decades-long journey.

Language: Английский

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Cerebral blood flow, cerebrovascular reactivity and their influence on ventilatory sensitivity

Experimental Physiology, Journal Year: 2021, Volume and Issue: 106(7), P. 1425 - 1448

Published: May 1, 2021

What is the topic of this review? Cerebrovascular reactivity to CO2 , which a principal factor in determining ventilatory responses through role plays cerebral extra- and intracellular pH. advances does it highlight? Recent animal evidence suggests central chemoreceptor vasculature may demonstrate regionally heterogeneous cerebrovascular potentially as protective mechanism against excessive washout from chemoreceptors, thereby allowing ventilation reflect systemic acid-base balance needs (respiratory changes PaCO2 ) rather than solely needs. Ventilation per se not influence independent .Alveolar blood flow are both predominantly regulated by arterial gases, especially PCO2 so intricately entwined. In review, fundamental mechanisms underlying control breathing covered. We discuss interaction its with responsiveness well lack itself on reactivity. briefly summarize effects hypoxaemia relationship between response PO2 . then highlight key methodological considerations regarding sensitivity, including following: regional heterogeneity reactivity; pharmacological approach for reduction flow; assessment techniques; mean pressure; sex-related differences. Finally, we context high altitude congestive heart failure. Future research directions pertinent questions interest highlighted throughout.

Language: Английский

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Abnormal skeletal muscle and myocardial vasoreactivity manifests prior to heart failure in a diabetic cardiomyopathy rat model

Deleted Journal, Journal Year: 2025, Volume and Issue: 2(1)

Published: Jan. 6, 2025

Microvascular dysfunction (MVD) is a recognized sign of disease in heart failure progression. Intact blood vessels exhibit abnormal vasoreactivity early stage, subsequently deteriorating to rarefaction and reduced perfusion. In managing with preserved ejection fraction (HFpEF), earlier diagnosis key improving management. this study, we applied steady-state blood-pool magnetic resonance imaging (MRI) method investigate if it can sensitively detect leg muscle vasoreactivity, MVD, posited manifest before structural functional cardiac changes emerge diabetes model HFpEF. Male female Sprague–Dawley rats were maintained on either high-fat, high-sugar diet or control for 6 months after the induction (n = 5 per group). Beginning at month 1 2 post-diabetes every thereafter, underwent MRI assess skeletal muscle, respectively. A T1-reducing agent was administered T1 relaxation time dynamically measured as animals breathed elevated CO2 levels modulate vessels. male rats, normally unresponsive 10% revealed pro-vasoconstriction response beginning post-diabetes. Abnormal appeared even earlier, months: usual vasodilatory 5% interrupted periods vasoconstriction diseased rats. differences observed between healthy only first not later. heart, vasodilation seen females abolished diabetic females. suboptimal inducing reproducible but young responded by only. presented than overt both cardiomyopathy, offered microvascular dysfunction.

Language: Английский

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Using Coherent Hemodynamic Spectroscopy Model to Investigate Cardiac Arrest

Algorithms, Journal Year: 2025, Volume and Issue: 18(3), P. 128 - 128

Published: Feb. 25, 2025

The Coherent Hemodynamic Spectroscopy (CHS) model provides a quantitative framework for modeling cerebral hemodynamics and metabolism, particularly in response to small physiological perturbations. However, its original approximate formulation it was limited conditions where parameter changes were constrained 10–20%, making unsuitable extreme disruptions such as cardiac arrest. In this study, we present detailed discussion of the algorithm using complete CHS model, which extends by solving partial differential equations without approximations handle large non-periodic This applied data from previously published arrest cardiopulmonary resuscitation (CPR) study pigs, blood flow changed 100%. While our prior work demonstrated utility approach analyzing microvascular metabolic parameters, did not include algorithmic details necessary reproducibility broader application. Here, address gap describing algorithm’s workflow, including use non-linear multivariate optimization, ability recover multiple variables, capillary venule oxygen saturations, diffusion rate, arterial saturation. latter can be valuable when pulse oximetry measurements are unavailable due unstable, weak or absent pulse. underscores importance advancing application highlights potential translational research clinical innovation.

Language: Английский

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Using depth-enhanced diffuse correlation spectroscopy and near-infrared spectroscopy to isolate cerebral hemodynamics during transient hypotension

Neurophotonics, Journal Year: 2023, Volume and Issue: 10(02)

Published: June 5, 2023

Combining diffuse correlation spectroscopy (DCS) and near-infrared (NIRS) permits simultaneous monitoring of multiple cerebral hemodynamic parameters related to autoregulation; however, interpreting these optical measurements can be confounded by signal contamination from extracerebral tissue.We aimed evaluate in NIRS/DCS data acquired during transient hypotension assess suitable means separating scalp brain signals.A hybrid time-resolved NIRS/multidistance DCS system was used simultaneously acquire oxygenation blood flow orthostatic induced rapid-onset lower body negative pressure (LBNP) nine young, healthy adults. Changes microvascular were verified against changes middle artery velocity (MCAv) measured transcranial Doppler ultrasound.LBNP significantly decreased arterial (-18%±14%), (>30%), tissue (all p≤0.04 versus baseline). However, implementing depth-sensitive techniques for both NIRS indicated that LBNP did not alter relative their baseline values p≥0.14). In agreement, there no significant reduction MCAv (8%±16%; p=0.09).Transient caused larger the compared brain. We demonstrate importance accounting within measures hemodynamics physiological paradigms designed test autoregulation.

Language: Английский

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Physiological responses, self‐reported health effects, and cognitive performance during exposure to carbon dioxide at 20 000 ppm

Indoor Air, Journal Year: 2021, Volume and Issue: 32(1)

Published: Oct. 4, 2021

In this study, 24 subjects (20–58 years) were exposed to carbon dioxide (CO2) at 770 ppm and 20 000 in an exposure laboratory for 4-h, including 2 × 15 min of cycling investigate the effects on acid-base balance, physiological responses, cognitive performance acute health. Capillary blood analysis, heart rate, respiratory divided attention, flexibility, sustained attention from Test Battery Attentional Performance (TAP), critical flicker fusion frequency (CFF), self-reported symptoms measured before, during, after 4-h exposure. Blood pH decreased partial pressure (pCO2) increased significantly when CO2 compared ppm. However, values remained within normal range. addition, rate slightly but CO2. No significant changes CFF, task or health found. sum, findings suggest that observed balance ventilation can be classified as adaptation responses. Impairment is not expected CO2, neither direct effect central nervous system function nor a distraction related perception effects.

Language: Английский

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Cerebral O₂ and CO₂ transport in isovolumic haemodilution: Compensation of cerebral delivery of O₂ and maintenance of cerebrovascular reactivity to CO₂

Journal of Cerebral Blood Flow & Metabolism, Journal Year: 2022, Volume and Issue: 43(1), P. 99 - 114

Published: Sept. 21, 2022

This study investigated the influence of acute reductions in arterial O2 content (CaO2) via isovolumic haemodilution on global cerebral blood flow (gCBF) and cerebrovascular CO2 reactivity (CVR) 11 healthy males (age; 28 ± 7 years: body mass index; 23 2 kg/m2). Radial artery internal jugular vein catheters provided measurement pressure gases, quantification metabolism, washout, trans-cerebral nitrite exchange (ozone based chemiluminescence). Prior to following haemodilution, partial (PaCO2) was elevated with dynamic end-tidal forcing while gCBF measured duplex ultrasound. CVR determined as slope response PaCO2. Replacement ∼20% volume an equal 5% human serum albumin (Alburex® 5%) reduced haemoglobin (13.8 0.8 vs. 11.3 0.6 g/dL; P < 0.001) CaO2 (18.9 1.0 vs 15.0 mL/dL 0.001), (+18 11%; = 0.002), preserved oxygen delivery (P 0.49), washout (+11%; 0.01). The net uptake (11.6 14.0 nmol/min; 0.027) at baseline abolished (-3.6 17.9 0.54), perhaps underpinning conservation (61.7 19.0 69.0 19.2 mL/min/mmHg; 0.23). These findings demonstrate that responses anaemia humans are sufficient support maintenance CVR.

Language: Английский

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Correspondence between BOLD fMRI task response and cerebrovascular reactivity across the cerebral cortex

Frontiers in Physiology, Journal Year: 2023, Volume and Issue: 14

Published: May 9, 2023

BOLD sensitivity to baseline perfusion and blood volume is a well-acknowledged fMRI confound. Vascular correction techniques based on cerebrovascular reactivity (CVR) might reduce variance due cerebral volume, however this predicated an invariant linear relationship between CVR signal magnitude. Cognitive paradigms have relatively low signal, high involve spatially heterogenous cortical regions; it therefore unclear whether the response magnitude complex can be predicted by CVR. The feasibility of predicting from was explored in present work across two experiments using different approaches. first utilized large database containing breath-hold responses 3 cognitive tasks. second experiment, independent sample, calculated delivery fixed concentration carbon dioxide task. An atlas-based regression approach implemented for both evaluate shared task-invoked cortex. Both found significant relationships task-based magnitude, with activation right cuneus (R2 = 0.64) paracentral gyrus 0.71), left pars opercularis 0.67), superior frontal 0.62) inferior parietal cortex 0.63) strongly regions bilaterally were highly consistent, regressions these all four Group analyses showed that increased sensitivity. Overall, suggests magnitudes tasks are cortex, providing support use vascular physiology.

Language: Английский

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