scholarly journals Transcranial Doppler Non-invasive Assessment of Intracranial Pressure, Autoregulation of Cerebral Blood Flow and Critical Closing Pressure during Orthotopic Liver Transplant

2019 ◽  
Vol 45 (6) ◽  
pp. 1435-1445 ◽  
Author(s):  
Danilo Cardim ◽  
Chiara Robba ◽  
Eric Schmidt ◽  
Bernhard Schmidt ◽  
Joseph Donnelly ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Intracranial Pressure ◽  
Liver Transplant ◽  
Transcranial Doppler ◽  
Orthotopic Liver Transplant ◽  
Non Invasive ◽  
Critical Closing Pressure ◽  
Pressure Autoregulation ◽  
Closing Pressure

Experimental cerebral hemodynamics

1974 ◽  
Vol 41 (5) ◽  
pp. 597-606 ◽  
Author(s):  
Richard C. Dewey ◽  
Heinz P. Pieper ◽  
William E. Hunt
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Mean Arterial Pressure ◽  
Intracranial Pressure ◽  
Perfusion Pressure ◽  
Brain Blood Flow ◽  
Vasomotor Tone ◽  
Vascular Bed ◽  
Critical Closing Pressure ◽  
Closing Pressure

✓ Application of Burton's concept of the critical closing pressure to experimental data on brain-blood flow in the monkey suggests that perfusion pressure, not vascular bed resistance, is the primary variable affecting cerebral blood flow. Perfusion pressure for the cerebral circulation is the mean arterial pressure minus the critical closing pressure (MAP — CCP). Vasomotor tone and intracranial pressure are the major determinants of the critical closing pressure. Changes in either of these variables, therefore, affect perfusion pressure and flow. Data on brain-blood flow at fixed vasomotor tone obtained over wide pressure ranges show little change in vascular bed resistance despite significant changes in flow. The diameter of resistance vessels probably does not change significantly throughout the normal physiological range of cerebral blood flow. The limits of the critical closing pressure in the anesthetized monkey are from 10 to 95 mm Hg. Using these limits, and beginning with the average values for MAP and CCP in 11 awake monkeys breathing room air, the authors present theoretical flow curves in response to changes in intracranial pressure and mean arterial pressure that closely approximate the data reported in man.

Influence of the mode of heating on cerebral blood flow, non‐invasive intracranial pressure and thermal tolerance in humans

2021 ◽  
Vol 599 (7) ◽  
pp. 1977-1996 ◽  
Author(s):  
Travis D. Gibbons ◽  
Philip N. Ainslie ◽  
Kate N. Thomas ◽  
Luke C. Wilson ◽  
Ashley P. Akerman ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Intracranial Pressure ◽  
Thermal Tolerance ◽  
Non Invasive

scholarly journals Transcranial Doppler

2015 ◽  
Vol 02 (03) ◽  
pp. 215-220
Author(s):  
Manish Marda ◽  
Hemanshu Prabhakar
Keyword(s):  
Decision Making ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Transcranial Doppler ◽  
Surrogate Marker ◽  
Vessel Diameter ◽  
Limiting Factor ◽  
Clinical Scenario ◽  
Non Invasive ◽  
Clinical Scenarios

AbstractTranscranial Doppler (TCD) is a bedside, non-invasive, reproducible, non-expensive neuromonitoring device which can be used in many clinical scenarios. Based on the principle of the Doppler shift, blood flow velocity (FV) in the cerebral vessels can be measured. It should be noted that TCD measures blood FV and not the cerebral blood flow (CBF). However, in a given condition, FV can be used as a surrogate marker for vessel diameter or CBF. Indirectly, it can also measure the CBF and the intracranial pressure. This review describes briefly the method of using the equipment and the various indices that can be measured. The applications of TCD are varied. The review also gives an account of the various clinical situations where TCD can be used. An inter-operator variability is an important limiting factor with the use of the TCD. However, in many of clinical scenario, the TCD can still be used to guide for decision-making.

Cessation of Diastolic Cerebral Blood Flow Velocity: The Role of Critical Closing Pressure

2013 ◽  
Vol 20 (1) ◽  
pp. 40-48 ◽  
Author(s):  
Georgios V. Varsos ◽  
Hugh K. Richards ◽  
Magdalena Kasprowicz ◽  
Matthias Reinhard ◽  
Peter Smielewski ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Flow Velocity ◽  
Blood Flow Velocity ◽  
Cerebral Blood Flow Velocity ◽  
Critical Closing Pressure ◽  
Closing Pressure

scholarly journals Noninvasive optical monitoring of critical closing pressure and arteriole compliance in human subjects

2017 ◽  
Vol 37 (8) ◽  
pp. 2691-2705 ◽  
Author(s):  
Wesley B Baker ◽  
Ashwin B Parthasarathy ◽  
Kimberly P Gannon ◽  
Venkaiah C Kavuri ◽  
David R Busch ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Continuous Monitoring ◽  
Human Subjects ◽  
Correlation Spectroscopy ◽  
Invasive Technique ◽  
Windkessel Model ◽  
Arterial Blood ◽  
Critical Closing Pressure ◽  
Closing Pressure

The critical closing pressure ( CrCP) of the cerebral circulation depends on both tissue intracranial pressure and vasomotor tone. CrCP defines the arterial blood pressure ( ABP) at which cerebral blood flow approaches zero, and their difference ( ABP −  CrCP) is an accurate estimate of cerebral perfusion pressure. Here we demonstrate a novel non-invasive technique for continuous monitoring of CrCP at the bedside. The methodology combines optical diffuse correlation spectroscopy (DCS) measurements of pulsatile cerebral blood flow in arterioles with concurrent ABP data during the cardiac cycle. Together, the two waveforms permit calculation of CrCP via the two-compartment Windkessel model for flow in the cerebral arterioles. Measurements of CrCP by optics (DCS) and transcranial Doppler ultrasound (TCD) were carried out in 18 healthy adults; they demonstrated good agreement (R = 0.66, slope = 1.14 ± 0.23) with means of 11.1 ± 5.0 and 13.0 ± 7.5 mmHg, respectively. Additionally, a potentially useful and rarely measured arteriole compliance parameter was derived from the phase difference between ABP and DCS arteriole blood flow waveforms. The measurements provide evidence that DCS signals originate predominantly from arteriole blood flow and are well suited for long-term continuous monitoring of CrCP and assessment of arteriole compliance in the clinic.

Carbon dioxide, critical closing pressure and cerebral haemodynamics prior to vasovagal syncope in humans

2001 ◽  
Vol 101 (4) ◽  
pp. 351-358 ◽  
Author(s):  
Brian J. CAREY ◽  
Penelope J. EAMES ◽  
Ronney B. PANERAI ◽  
John F. POTTER
Keyword(s):  
Carbon Dioxide ◽  
Blood Pressure ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Vasovagal Syncope ◽  
Previous History ◽  
Normal Subjects ◽  
Cerebrovascular Resistance ◽  
Critical Closing Pressure ◽  
Closing Pressure

The cerebrovascular changes that occur prior to vasovagal syncope (VVS) are unclear, with both increases and decreases in cerebrovascular resistance being reported during pre-syncope. This study assessed the cerebrovascular responses, and their potential underlying mechanisms, that occurred before VVS induced by head-up tilt (HUT). Groups of 65 normal subjects with no previous history of syncope and of 16 patients with recurrent VVS were subjected to 70° HUT for up to 30min. Bilateral middle cerebral artery (MCA) cerebral blood flow velocities (CBFVs) were measured using transcranial Doppler ultrasound, along with simultaneous measures of MCA blood pressure, heart rate, and end-tidal and transcutaneous carbon dioxide concentrations. All 16 patients and 14 of the control subjects developed VVS during HUT. During pre-syncope, mean CBFV declined, due predominantly to a decrease in diastolic rather than systolic CBFV (decreases of 44.5±;19.8% and 6.3±;12.9% respectively; P < 0.0001). CO2 levels and indices of cerebrovascular resistance decreased during pre-syncope, while critical closing pressure (CrCP) increased to levels approaching MCA diastolic blood pressure before decreasing precipitously on syncope. Pre-syncopal changes were similar in syncopal patients and syncopal controls. CrCP, therefore, rises during pre-syncope, possibly related to progressive hypocapnia, and may account for the relatively greater fall in diastolic CBFV. Falls in cerebrovascular resistance, therefore, may be offset by rises in CrCP due to hypocapnia, leading to diminished cerebral blood flow during pre-syncope.

scholarly journals Randomized Control Trial For Transcranial Doppler monitoring in patients with Traumatic Brain Injury.

2020 ◽  
Author(s):  
Nida Fatima
Keyword(s):  
Traumatic Brain Injury ◽  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Brain Injury ◽  
Intracranial Pressure ◽  
Transcranial Doppler ◽  
Traumatic Event ◽  
Intervention Group ◽  
Control Group ◽  
Neurosurgical Intervention

Abstract Traumatic Brain Injury is the leading cause of disability and mortality throughout the world. It temporarily or permanently impairs the brain function. Primary injury is induced by mechanical forces and occurs at the moment of injury while secondary brain damage may occurs hours or even days after the traumatic event. This injury may result from impairment or local decline in the cerebral blood flow. Decreases in cerebral blood flow are the result of local edema, hemorrhage or increased intracranial pressure. Although major progress has been made in understanding of the pathophysiology of this injury, this has not yet led to substantial improvements in outcome. Traumatic Brain Injury is associated with various complications including raised intracranial pressure, midline shift due to worsening of the volume of intracranial hematoma, cerebral vasospasm in traumatic sub arachnoid hemorrhage. Transcranial Doppler (TCD) has been utilized as a monitoring tool in the neurocritical care unit since it is non-invasive tool and that can be brought to bedside.However, its utility in using as a protocol in management of traumatic brain injury patients has not been studied.We hypothesized that daily TCD followed by early performance of Neuroimaging (CT scan) and Neurosurgical intervention will lead to improvement in clinical outcome.Our study’s design is Randomized Controlled Trial with neurosurgical intervention based upon the Intervention Group as the TCD-Monitoring/Neuroimaging vs Control Group as the Clinical Imaging/Neurological status. Our study’s outcome is 90 days’ clinical outcome (modified rankin scale) and Glasgow Coma Outcome Scale.

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