Cerebral Blood Flow Velocity during and after Sustained Isometric Skeletal Muscle Contractions in Man

1998 ◽  
Vol 94 (4) ◽  
pp. 353-358 ◽  
Author(s):  
F. J. Imms ◽  
F. Russo ◽  
V. I. Iyawe ◽  
M. B. Segal
Keyword(s):  
Middle Cerebral Artery ◽  
Flow Velocity ◽  
Cerebral Artery ◽  
Cerebral Blood Flow Velocity ◽  
Volume Flow ◽  
Mean Flow ◽  
Arterial Blood ◽  
End Tidal ◽  
The Right ◽  
The Brain

1. Twenty-seven young subjects used their right hand to perform sustained, isometric contractions at 40% of maximum for 2 min while lying supine. 2. During the last 30 s of exercise, mean arterial blood pressure increased by 38 ± 4 mmHg (mean ± S.E.M.) and heart rate by 27 ± 2 beats/min. 3. Nineteen of the subjects respired eucapnically during exercise, increasing ventilation by 4.1 ± 0.5 litres/min. Eight subjects hyperventilated (7.1–19.6 litres/min) and decreased end-tidal Pco2 by 8.2 to 15.1 mmHg during the last minute of exercise. 4. In the eucapnic subjects mean flow velocity in the right (i.e. contralateral to the activated cortex) middle cerebral artery increased by 11.4 ± 1.0 cm/s, a change of 17%, during the contraction. This represents an increase in volume flow to the territory of this vessel, but an increase in global flow to the brain cannot be inferred. 5. In the eight subjects who hyperventilated during exercise, there was no rise of flow velocity in the middle cerebral artery, and in some subjects there was a fall during the first 2 min of recovery. These findings suggest that if subjects hyperventilate during handgrip exercise there could be a fall in volume flow to many regions of the brain during and after the exercise.

Determinants of cerebral blood flow velocity change during squat-stand maneuvers

2021 ◽  
Vol 320 (4) ◽  
pp. R452-R466
Author(s):  
Ronney B. Panerai ◽  
Angus Batterham ◽  
Thompson G. Robinson ◽  
Victoria J. Haunton
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Flow Velocity ◽  
Blood Flow Velocity ◽  
Cerebral Blood Flow Velocity ◽  
Velocity Change ◽  
Arterial Blood ◽  
Autoregulation Index ◽  
End Tidal ◽  
The Right

The large changes in mean arterial blood pressure (MABP) and cerebral blood flow velocity (CBFV) induced by squat-stand maneuvers (SSM) make this approach particularly suited for studying dynamic cerebral autoregulation (CA). However, the role of other systemic determinants of CBFV has not been described and could provide alternative physiological interpretations of SSM results. In 32 healthy subjects (16 female), continuous recordings of MABP (Finometer), bilateral CBFV (transcranial Doppler, MCA), end-tidal CO2 (EtCO2; capnography), and heart rate (HR; electrocardiogram) were performed for 5 min standing at rest, and during 15 SSM at the frequency of 0.05 Hz. A time-domain, multivariate dynamic model estimated the CBFV variance explained by different inputs, corresponding to significant contributions from MABP ( P < 0.00001), EtCO2 ( P < 0.0001), and HR ( P = 0.041). The autoregulation index (ARI; range 0–9) was estimated from the CBFV response to a step change in MABP. At rest, ARI values (typically 5.7) were independent of the number of model inputs, but during SSM, ARI was reduced compared with baseline ( P < 0.0001), and the three input model yielded lower values for the right and left MCA (3.4 ± 1.2, 3.1 ± 1.3) when compared with the single-input MABP–CBFV model (4.1 ± 1.1, 3.9 ± 1.0; P < 0.0001). The high coherence of the MABP–CBFV transfer function at 0.05 Hz (typically 0.98) was considerably reduced (around 0.71–0.73; P < 0.0001) when the contribution of CBFV covariates was taken into account. Not taking into consideration other determinants of CBFV, in addition to MABP, could be misleading and introduce biases in physiological and clinical studies.

scholarly journals Differential Increases in Blood Flow Velocity in the Middle Cerebral Artery after Tourniquet Deflation during Sevoflurane, Isoflurane or Propofol Anaesthesia

2009 ◽  
Vol 37 (4) ◽  
pp. 598-603 ◽  
Author(s):  
Y. Kadoi ◽  
C. H. Kawauchi ◽  
M. Ide ◽  
S. Saito ◽  
A. Mizutani
Keyword(s):  
Blood Flow ◽  
Middle Cerebral Artery ◽  
Flow Velocity ◽  
Cerebral Artery ◽  
Blood Flow Velocity ◽  
Orthopaedic Surgery ◽  
Cerebral Blood Flow Velocity ◽  
Pneumatic Tourniquet ◽  
Arterial Blood ◽  
Tourniquet Deflation

The purpose of this study was to examine the comparative effects of sevoflurane, isoflurane or propofol on cerebral blood flow velocity after tourniquet deflation during orthopaedic surgery. Thirty patients undergoing elective orthopaedic surgery were randomly divided into sevoflurane, isoflurane and propofol groups. Anaesthesia was maintained with sevoflurane, isoflurane or propofol infusion in 33% oxygen and 67% nitrous oxide, in whatever concentrations were necessary to keep bispectral index values between 45 and 50. Ventilatory rate or tidal volume was adjusted to target PaCO2 of 35 mmHg. A 2.0 MHz transcranial Doppler probe was attached to the patient's head at the temporal window and mean blood flow velocity in the middle cerebral artery was continuously measured. The extremity was exsanguinated with an Esmarch bandage and the pneumatic tourniquet was inflated to a pressure of 450 mmHg. Arterial blood pressure, heart rate, velocity in the middle cerebral artery and arterial blood gas analysis were measured every minute for 10 minutes after release of the tourniquet in all three groups. Velocity in the middle cerebral artery in the three groups increased for five minutes after tourniquet deflation. Because of the different cerebrovascular effects of the three agents, the degree of increase in flow velocity in the isoflurane group was greater than in the other two groups, the change in flow velocity in the propofol group being the lowest (at three minutes after deflation 40∓7%, 32∓6% and 28∓10% in the isoflurane, sevoflurane and propofol groups respectively, P <0.05).

Transmyocardial Laser Revascularization Induces Cerebral Microembolization 

1997 ◽  
Vol 87 (1) ◽  
pp. 58-62 ◽  
Author(s):  
Georg von Knobelsdorff ◽  
Patrick Brauer ◽  
Peter H. Tonner ◽  
Frank Hanel ◽  
Herbert Naegele ◽  
...  
Keyword(s):  
Middle Cerebral Artery ◽  
Flow Velocity ◽  
Cerebral Artery ◽  
Transcranial Doppler ◽  
Doppler Sonography ◽  
Transcranial Doppler Sonography ◽  
Jugular Bulb ◽  
Arterial Blood ◽  
Transmyocardial Laser Revascularization ◽  
The Right

Background Transmyocardial laser revascularization may vaporize fluid in the left heart, allowing bubbles to form. This study aimed to determine whether the laser pulse resulted in cerebral emboli and to examine changes in middle cerebral artery flow velocity and jugular bulb oxygen saturation (SjO2) during transmyocardial laser revascularization. Methods Twelve patients (American Society of Anesthesiologists physical status III) were studied after the authors received institutional review board approval and the patients' informed consent. Monitored variables included mean arterial blood pressure (measured in millimeters of mercury), heart rate (measured as beats/min), and partial pressure of carbon dioxide (measured in millimeters of mercury). A 5-MHz transesophageal-sonography system was used to record intraventricular events after laser injection. Mean blood flow velocity (Vmean; measured in centimeters per second) was monitored in the middle cerebral artery using transcranial Doppler sonography, and SjO2 (expressed as a percentage) was measured using a fiberoptic thermodilution catheter placed in the right jugular bulb. Data were recorded before, during, and for 4 min after laser injection. Results After laser injection, intraventricular echogenic contrast was seen in transesophageal-sonography, and 2-4 s later high-intensity signals (microemboli) appeared in the transcranial Doppler sonography spectra. As long as mean arterial pressure remained stable during the observation period, Vmean and SjO2 did not change. Conclusions These data show that microemboli can be detected after laser injection in the middle cerebral artery, although they do not effect Vmean and SjO2. The results suggest that these microemboli do not induce a global oxygen imbalance.

scholarly journals Bilateral Simultaneous Assessment of Cerebral Flow Velocity during Mental Activity

1994 ◽  
Vol 14 (4) ◽  
pp. 643-648 ◽  
Author(s):  
Mauro Silvestrini ◽  
Letizia M. Cupini ◽  
Maria Matteis ◽  
Elio Troisi ◽  
Carlo Caltagirone
Keyword(s):  
Middle Cerebral Artery ◽  
Flow Velocity ◽  
Cerebral Artery ◽  
Mental Activity ◽  
Absolute Difference ◽  
Mean Flow ◽  
Visual Imaging ◽  
The Right ◽  
Left Middle ◽  
Mental Tasks

The purpose of this study was to assess the potential of transcranial Doppler (TCD) ultrasonography for detecting selective changes in cerebral blood flow velocity during mental activity. Mean flow velocity was continuously and simultaneously measured in the right and left middle cerebral arteries in 26 healthy right-handed young subjects at rest and during performance of verbal and visual-imaging mental tasks. These two mental tasks produced significantly different effects on the right and left sides: the verbal task produced a higher increase of flow velocity (mean absolute difference above baseline ± SD) with respect to the basal values in the left than in the right middle cerebral artery (5.56 ±3.8 cm/s vs 1.25 ± 3.1 cm/s); the visual-imaging task was accompanied by a higher increase in the right than in the left middle cerebral artery (3.92 ± 3.3 cm/s vs 1.52 ± 3.1 cm/s)—analysis of variance (ANOVA) three-fold interaction side of recording × task × condition, F = 25.67, p < .0001). Heart rate, blood pressure, and skin conductance showed comparable increases during performance of both mental tasks. Respiratory activity showed no modification during the mental activity with respect to the rest phase. These results demonstrate the possibility of delivering specific functional information via bilateral TCD and suggest wider utilization of this noninvasive technique in neuropsychological studies.

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.

scholarly journals Risk Factors for Delayed Neurocognitive Recovery According to Brain Biomarkers and Cerebral Blood Flow Velocity

Medicina ◽  
2020 ◽  
Vol 56 (6) ◽  
pp. 288
Author(s):  
Rasa Bukauskienė ◽  
Edmundas Širvinskas ◽  
Tadas Lenkutis ◽  
Rimantas Benetis ◽  
Rasa Steponavičiūtė
Keyword(s):  
Risk Factors ◽  
Blood Flow ◽  
Middle Cerebral Artery ◽  
Flow Velocity ◽  
Cerebral Artery ◽  
Blood Flow Velocity ◽  
Cerebral Blood Flow Velocity ◽  
Co2 Concentration ◽  
Anesthesia Induction ◽  
Neurocognitive Evaluation

Background and Objectives: The aim of this study is to identify risk factors for the development of delayed neurocognitive recovery (dNCR). Materials and Methods: 140 patients underwent neurocognitive evaluations (Adenbrooke, MoCa, trial making, and CAM test) and middle cerebral artery (MCA) blood flow velocity (BFV) measurements, one day before cardiac surgery. BFV was re-evaluated after anesthesia induction, before the beginning, middle, end, and after cardiopulmonary bypass (CPB) and postsurgery. To measure glial fibrillary acidic protein (GFAP) and neurofilament heavy chain (Nf-H), blood samples were collected after anesthesia induction, 24 and 48 h after the surgery. Neurocognitive evaluation was repeated 7–10 days after surgery. According to the results, patients were divided into two groups: with dNCR (dNCR group) and without dNCR (non-dNCR group). Results: 101 patients completed participation in this research. GFAP increased in both the non-dNCR group (p < 0.01) and in the dNCR group (p < 0.01), but there was no difference between the groups (after 24 h, p 0.342; after 48 h, p 0.273). Nf-H increased in both groups (p < 0.01), but there was no difference between them (after 24 h, p = 0.240; after 48 h, p = 0.597). MCA BFV was significantly lower in the dNCR group during the bypass (37.13 cm/s SD 7.70 versus 43.40 cm/s SD 9.56; p = 0.001) and after surgery (40.54 cm/s SD 11.21 versus 47.6 cm/s SD 12.01; p = 0.003). Results of neurocognitive tests correlated with CO2 concentration (Pearson’s r 0.40, p < 0.01), hematocrit (r 0.42, p < 0.01), MCA BFV during bypass (r 0.41, p < 0.01), and age (r −0.533, p < 0.01). The probability of developing dNCR increases 1.21 times with every one year of increased age (p < 0.01). The probability of developing dNCR increases 1.07 times with a decrease of BFV within 1 cm/s during bypass (p = 0.02). Conclusion: Risk factors contributing to dNCR among the tested patients were older age and middle cerebral artery blood flow velocity decrease during bypass.

Effects of Sufentanil on Cerebral Hemodynamics and Intracranial Pressure in Patients with Brain Injury

1995 ◽  
Vol 83 (4) ◽  
pp. 721-726. ◽  
Author(s):  
Christian Werner ◽  
Eberhard Kochs ◽  
Hanswerner Bause ◽  
William E. Hoffman ◽  
Jochen Schulte am Esch
Keyword(s):  
Blood Flow ◽  
Middle Cerebral Artery ◽  
Flow Velocity ◽  
Cerebral Artery ◽  
Blood Flow Velocity ◽  
Artery Blood Flow ◽  
Arterial Blood ◽  
Norepinephrine Infusion ◽  
Group 2 ◽  
Group 1

Background The current study investigates the effects of sufentanil on cerebral blood flow velocity and intracranial pressure (ICP) in 30 patients with intracranial hypertension after severe brain trauma (Glasgow coma scale &lt; 6). Methods Mechanical ventilation (FIO2 0.25-0.4) was adjusted to maintain arterial carbon dioxide tensions of 28-30 mmHg. Continuous infusion of midazolam (200 micrograms/kg/h intravenous) and fentanyl (2 micrograms/kg/h intravenous) was used for sedation. Mean arterial blood pressure (MAP, mmHg) was adjusted using norepinephrine infusion (1-5 micrograms/min). Mean blood flow velocity (Vmean, cm/s) was measured in the middle cerebral artery using a 2-MHz transcranial Doppler sonography system. ICP (mmHg) was measured using an epidural probe. After baseline measurements, a bolus of 3 micrograms/kg sufentanil was injected, and all parameters were continuously recorded for 30 min. The patients were assigned retrospectively to the following groups according to their blood pressure responses to sufentanil: group 1, MAP decrease of less than 10 mmHg, and group 2, MAP decrease of more than 10 mmHg. Results Heart rate, arterial blood gases, and esophageal temperature did not change over time in all patients. In 18 patients, MAP did not decrease after sufentanil (group 1). In 12 patients, sufentanil decreased MAP &gt; 10 mmHg from baseline despite norepinephrine infusion (group 2). ICP was constant in patients with maintained MAP (group 1) but was significantly increased in patients with decreased MAP. Vmean did not change with sufentanil injection regardless of changes in MAP. Conclusions The current data show that sufentanil (3 micrograms/kg intravenous) has no significant effect on middle cerebral artery blood flow velocity and ICP in patients with brain injury, intracranial hypertension, and controlled MAP. However, transient increases in ICP without changes in middle cerebral artery blood flow velocity may occur concomitant with decreases in MAP. This suggests that increases in ICP seen with sufentanil may be due to autoregulatory decreases in cerebral vascular resistance secondary to systemic hypotension.

Slow oscillations in middle cerebral artery cerebral blood flow velocity and aging

2007 ◽  
Vol 29 (3) ◽  
pp. 260-263 ◽  
Author(s):  
Philip M. Lewis ◽  
Piotr Smielewski ◽  
John D. Pickard ◽  
Marek Czosnyka
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Middle Cerebral Artery ◽  
Flow Velocity ◽  
Cerebral Artery ◽  
Blood Flow Velocity ◽  
Cerebral Blood Flow Velocity ◽  
Slow Oscillations

Influence of posture on middle cerebral artery mean flow velocity in humans

1995 ◽  
Vol 71 (2-3) ◽  
pp. 161-165 ◽  
Author(s):  
E. Savin ◽  
O. Bailliart ◽  
A. Checoury ◽  
P. Bonnin ◽  
C. Grossin ◽  
...  
Keyword(s):  
Middle Cerebral Artery ◽  
Flow Velocity ◽  
Cerebral Artery ◽  
Mean Flow ◽  
Mean Flow Velocity
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