Abstract WP432: Non-invasive Respiratory Impedance Enhances Cerebral Perfusion

Stroke ◽  
2017 ◽  
Vol 48 (suppl_1) ◽  
Author(s):  
Christopher G Favilla ◽  
Ashwin B Parthasarathy ◽  
John A Detre ◽  
Michael T Mullen ◽  
Scott E Kasner ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Flow Velocity ◽  
Cerebral Perfusion ◽  
Respiratory Impedance ◽  
Mean Flow ◽  
Non Invasive ◽  
End Tidal ◽  
High Level ◽  
Mean Flow Velocity

Background: Optimization of cerebral blood flow is the cornerstone of clinical management in a number of neurologic diseases, most notably ischemic stroke. Intra-thoracic pressure influences cardiac output and has the potential to impact cerebral blood flow (CBF). Here we aim to quantify cerebral hemodynamic changes in response to increased respiratory impedance using a non-invasive respiratory device. Methods: Cerebral perfusion was measured under varying levels of respiratory impedance (6cm H 2 0, 9cm H 2 0, and 12 cm H 2 0) in 20 healthy volunteers. Simultaneous measurements of microvascular CBF and middle cerebral artery mean flow velocity (MFV), respectively, were performed with optical diffuse correlation spectroscopy (DCS) and transcranial Doppler ultrasound (TCD). Results: At the high level of respiratory impedance, mean flow velocity increased by 6.4% compared to baseline (p=0.004), but changes in cortical CBF were smaller and non-significant (Figure). Heart rate, cardiac output, respiratory rate, and end tidal CO 2 remained stable during all levels of respiratory impedance. There was small increase in mean arterial blood pressure, 1.7% (p=0.006), at the high level of respiratory impedance. In a multivariable linear regression model accounting for end tidal CO 2 and individual variability, respiratory impedance was associated with increases in both mean flow velocity (coefficient: 0.49, p<0.001) and cortical CBF (coefficient: 0.13, p<0.001). Conclusions: Manipulating intrathoracic pressure via non-invasive respiratory impedance was well tolerated and produced a small but measurable increase in cerebral perfusion in healthy individuals. Future studies in acute ischemic stroke patients with impaired cerebral autoregulation is warranted in order to assess whether respiratory impedance is feasible as a novel non-invasive therapy for stroke.

scholarly journals Non-invasive evaluation of cerebral hemodynamic and intracranial pressure in pediatric neuroinfections

2018 ◽  
Vol 9 (4) ◽  
pp. 485-490
Author(s):  
М. А. Georgiynts ◽  
V. А. Коrsunov ◽  
О. М. Оlkhovska ◽  
К. E. Stoliarov
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Cardiac Output ◽  
Intensive Care ◽  
Intracranial Pressure ◽  
Cerebral Perfusion ◽  
Flow Index ◽  
Non Invasive ◽  
Group I ◽  
Group Ii

The study of intracranial pressure (eICP), cerebral perfusion pressure (eCPP), cerebral blood flow index (CFI), zero flow pressure (ZFP) in 49 children hospitalized in the intensive care unit with severe course of neuroinfections was carried out. The level of consciousness was determined by the Glasgow pediatric scale. Monitoring of central and peripheral hemodynamics (ECG, heart rate, systolic, diastolic and mean blood pressure, and cardiac output), pulse oximetry, capnography, hemoglobin, hematocrit, total protein, urea, creatinine, lactate, glucose and serum electrolytes was done. An ultrasound scanner was used to perform ultrasound duplex scanning of blood flow in the left and middle cerebral artery (MCA), measuring maximum, minimum and average blood flow velocities, pulsation index (PI), and resistance index (RI). Based on the formulae of Edouard et al. indicators of eCPP, ZFP, CFI, eICP were calculated. The eSCP was also determined by the formulae of Kligenchöfer et al. and Bellner et al. All patients were divided into group I with RI > 1.3 and group II with RI < 1.3. It was found that eCPP in the group I was significantly less (29.5 ± 1.3 mm Hg) than in the II group (41.6 ± 1.7 mm Hg). Despite the lack of a reliable difference in blood pressure between groups I and II, the difference in eCPP was found due to a significant difference in eICP 34.6 ± 1.4 and 27.6 ± 0.89 mm Hg in I and II groups respectively. ZFP in group I was significantly higher than in group II. The indexes of the Glasgow coma scale was significantly lower in group I and 7.8 ± 0.6 points. There were observed direct moderate correlations between systolic blood pressure, cardiac output and eSRP and CFI, presumably associated with a loss of autoregulation. CFI in the group I was lower than in the group II. Thus, non-invasive examination of cerebral flow in MCA by duplex sonography revealed that PI > 1.3 is an informative marker of intracranial hypertension and reduction of cerebral perfusion, which is common in children with neuroinfections. To determine the eSRP and CFI it is advisable to use the formula of Edouard et al. and to determine the eICP the formula of Kligenchöfer et al. The obtained data can be useful for objectifying the severity of the condition, predicting the outcomes of neuroinfections, choosing the directions of intensive care and evaluating its effectiveness.

Cerebral Blood Flow Velocity Changes in Preterm Infants After a Single Dose of Indomethacin: Duration of Its Effect

PEDIATRICS ◽  
1989 ◽  
Vol 84 (5) ◽  
pp. 802-807
Author(s):  
Frank Van Bel ◽  
Margot Van de Bor ◽  
Theo Stijnen ◽  
Jan Baan ◽  
Jan H. Ruys
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Preterm Infant ◽  
Flow Velocity ◽  
Preterm Infants ◽  
Blood Flow Velocity ◽  
Cerebral Blood Flow Velocity ◽  
Cerebral Arteries ◽  
Mean Flow ◽  
Mean Flow Velocity

Indomethacin decreases cerebral blood flow velocity and blood flow in the preterm infant. The duration of this negative effect has not been established. Cerebral blood flow velocity was evaluated in 24 preterm infants with symptomatic patent ductus arteriosus before and during the first 12 hours after a single intravenous dose of indomethacin, 0.1 mg/kg. Cerebral blood flow velocity was estimated by serial Doppler investigations of the anterior cerebral arteries. Indomethacin administration led to an instantaneous decrease of peak systolic flow velocity, temporal mean flow velocity, and end-diastolic flow velocity of the anterior cerebral arteries in all infants, which was maximal between 2 and 40 minutes after indomethacin administration and was followed by a more sustained recovery of all velocities to baseline values. Temporal mean flow velocity was not different from pre-indomethacin values at 3 hours after the administration. It is concluded that indomethacin can impact the cerebral circulation of the preterm infant for at least 2 hours. This may have consequences in preterm infants with unstable hemodynarnics and pulmonary function.

Factors influencing the change in cerebral hemodynamics in pediatric patients during and after corrective cardiac surgery of congenital heart diseases by means of full-flow cardiopulmonary bypass

Perfusion ◽  
2002 ◽  
Vol 17 (3) ◽  
pp. 179-185 ◽  
Author(s):  
Hashim Abdul-Khaliq ◽  
Ralph Uhlig ◽  
Wolfgang Böttcher ◽  
Peter Ewert ◽  
Vladimir Alexi-Meskishvili ◽  
...  
Keyword(s):  
Cardiac Surgery ◽  
Flow Velocity ◽  
Rectal Temperature ◽  
Cerebral Perfusion ◽  
Congenital Heart ◽  
Qualitative Assessment ◽  
Mean Flow ◽  
Normothermic Group ◽  
Mean Flow Velocity ◽  
Hypothermic Group

Background: The pathophysiology of hypoxic -ischemic brain injury in relation to extracorporeal circulation is multifactorial and can be interpreted, in part, as possible alteration in cerebral perfusion and inadequate oxygen delivery to the brain cells. The aim of this study was to evaluate influencing factors on the change in cerebral blood flow velocity (CBFV) patterns determined by transcranial Doppler sonography (TCD) in infants who undergo corrective cardiac surgery by means of full-flow cardio-pulmonary bypass (CPB). Methods: Included in the study were 67 neonates, infants, and children with a median age of 4 months (0.1-70 months), median weight of 4.8 kg (2.5-18.8 kg), and with cyanotic and noncyanotic congenital heart disease (CHD), who underwent surgical correction of CHD by means of CPB [flow rate 144± 47 ml/kg body weight (BW)] and the alpha-stat strategy. The patients were divided into three groups with respect to the minimum rectal temperature during perfusion: deep hypothermic CPB (< 18°C) n= 18, moderate hypothermic CPB (22-35°C) n= 29, normothermic CPB (36°C) n=20. Continuous determination of mean flow velocity (Vmean) in the middle cerebral artery (MCA) by TCD provided qualitative on-line information on cerebral perfusion. The pulsatility index (PI) was calculated in accordance with the formula: PI = Maximum flow velocity -end -diastolic flow velocity/Mean flow velocity and was used as a parameter for the qualitative assessment of cerebrovascular resistance after the end of CPB. Results: The Vmean was significantly increased 15 min after cross-clamping in the normothermic group ( p= 0.03) and decreased in the moderate hypothermic group ( p=0.02) and deep hypothermic group ( p= 0.009). The postoperative Vmean values correlated significantly with age ( r= 0.79, p< 0.0001), weight ( r= 0.75, p< 0.0001), bypass time ( r=-0.51, p=0.0006), and minimum rectal temperature ( r= 0.60, p= 0.0001). Mean arterial pressure and hemoglobin concentration, but not pCO2, seem to significantly influence the change in Vmean after the termination of CPB ( r= 0.5, p= 0.001; r= -0.55, p= 0.002, respectively). In comparison with the values at the start of CPB, the Vmeanwas significantly decreased after the end of CPB in the hypothermic and moderate hypothermic groups and still significantly elevated in the normothermic group. The age-independent PI was increased after termination of bypass in all groups ( p<0.05) and still slightly elevated after the end of operation in the hypothermic group ( p= 0.05). Conclusions: The changes in CBFV patterns before, during, and after the termination of CPB were dependent on age, weight, perfusion pressure, and degree of hypothermia during CPB.

Experimental Investigation of the Acoustic Reflection Coefficient of a Modeled Gas Turbine Impingement Cooling Section

2012 ◽  
Author(s):  
Christoph Jörg ◽  
Michael Wagner ◽  
Thomas Sattelmayer
Keyword(s):  
Reflection Coefficient ◽  
Flow Velocity ◽  
Gas Turbines ◽  
Acoustic Energy ◽  
Quality Data ◽  
Mean Flow ◽  
Impingement Cooling ◽  
Acoustic Reflection ◽  
The Mean ◽  
Mean Flow Velocity

The thermoacoustic stability of gas turbines depends on a balance of acoustic energy inside the engine. While the flames produce acoustic energy, other areas like the impingement cooling system contribute to damping. In this paper, we investigate the damping potential of an annular impingement sleeve geometry embedded into a realistic environment. A cold flow test rig was designed to represent real engine conditions in terms of geometry, and flow situation. High quality data was delivered by six piezoelectric dynamic pressure sensors. Experiments were carried out for different mean flow velocities through the cooling holes. The acoustic reflection coefficient of the impingement sleeve was evaluated at a downstream reference location. Further parameters investigated were the number of cooling holes, and the geometry of the chamber surrounding the impingement sleeve. Experimental results show that the determining parameter for the reflection coefficient is the mean flow velocity through the impingement holes. An increase of the mean flow velocity leads to significantly increased damping, and to low values of the reflection coefficient.

Direct Cerebral Vasodilatory Effects of Sevoflurane and Isoflurane 

1999 ◽  
Vol 91 (3) ◽  
pp. 677-677 ◽  
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&lt;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.

Objective duplex ultrasound evaluation of the extracranial circulation in multiple sclerosis patients undergoing venoplasty of internal jugular vein stenoses: A pilot study

2013 ◽  
Vol 30 (2) ◽  
pp. 98-104 ◽  
Author(s):  
P Thibault ◽  
W Lewis ◽  
S Niblett
Keyword(s):  
Multiple Sclerosis ◽  
Blood Flow ◽  
Cerebral Perfusion ◽  
Objective Assessment ◽  
Duplex Ultrasound ◽  
Additional Parameter ◽  
Non Invasive ◽  
Venous Circulation ◽  
Ultrasound Evaluation ◽  
Multiple Sclerosis Patients

Objective Chronic cerebrospinal venous insufficiency (CCSVI) is a condition associated with multiple sclerosis (MS) and manifested by stenoses in the extracranial venous circulation. There is a need for an objective non-invasive assessment of CCSVI that is able to accurately identify the location of stenoses and quantify physiological changes in blood flows following treatment. Method A duplex ultrasound method, extracranial duplex ultrasound (ECDU), is described where the internal jugular veins (IJVs) and vertebral veins (VVs) were examined in the supine and sitting position before and after venoplasty in eight patients with clinically diagnosed MS. High-resolution B-mode imaging was used to detect obvious stenoses, intra-luminal membranes, valve abnormalities and vein wall thickening. ECDU was then used to assess blood flow including reflux. To assess obstruction, venous blood volume flows (BVFs) were taken bilaterally from the proximal (J1), mid (J2) and distal (J3) segments of the IJVs and the mid cervical VVs. To assess cerebral perfusion, bilateral BVF measurements were taken, in the supine position only, from the proximal internal carotid arteries (ICA) and mid cervical vertebral arteries (VA). The global arterial cerebral blood flow (GACBF) was then calculated as the sum of the ICA and VA measurements. Results Pre-venography ECDU detected IJV stenoses or obstruction in all patients. Venography findings were consistent with those of the pre-treatment ECDU with the exception of the detection of bilateral IJV stenoses in two patients diagnosed with unilateral IJV stenosis by ECDU. A significant improvement in GACBF was evident following venoplasty ( p < 0.05). A trend to improvement in the post-treatment BVFs of both the IJVs and the mid cervical VVs was also observed. This improvement was most marked in the left VVs ( p = 0.052) and the J2 segment of right IJVs ( p < 0.05). Conclusion The ECDU examination described provides a reliable objective assessment of IJV and VV stenoses and, with the use of BVFs, can quantify the degree of obstruction. These results support the use of ECDU as a non-invasive post-operative assessment of the success of venoplasty. The ability of ECDU to measure GACBF provides an additional parameter to monitor vascular pathophysiology in MS patients. The current findings support the view that the early symptomatic benefits observed after venoplasty for stenoses in the extracranial venous circulation may be the result of increased cerebral perfusion.

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