Changes In Blood Flow Velocity Research Articles

The efficacy of ultrasonography in monitoring the healing of jaw lesions.

PurposeThis study aimed to assess the reliability of ultrasonography (US) in comparison with cone-beam computed tomography (CBCT) as a tool for monitoring the healing of jaw lesions.Materials and MethodsTwenty-one radiolucent lesions in jaws referred to the Oral Surgery Department at our institution were selected for this study. All lesions underwent CBCT and US examinations. The anteroposterior, superoinferior, and mesiodistal dimensions of the lesions were measured on CBCT and US images before surgery and at 6 months after surgery. The dimensions were compared between the US and CBCT images. Blood-flow velocity around the lesions was measured by color Doppler before surgery and at 1 week and 6 months after surgery to assess the capability of US to show changes in blood-flow velocity around the lesion.ResultsBefore surgery, there were no significant differences between US and CBCT in the mesiodistal and anteroposterior dimensions, although a significant difference was found in the superoinferior dimension (P<.05). However, at 6 months after surgery, significant differences were found between US and CBCT in all dimensions, and it is likely that the US measurements more accurately reflected the extent of healing. The average blood-flow velocity increased at 1 week after surgery (5.84 cm/s) compared with the velocity before surgery (4 cm/s) (P<.05). Then, at 6 months after surgery, the blood-flow velocity significantly decreased (3.53 cm/s) compared to the velocity measured at 1 week after surgery (P<.05).ConclusionUS with color Doppler was confirmed to be a more efficient tool than CBCT for monitoring bone healing.

Fenofibrate attenuates cardiac and renal alterations in young salt-loaded spontaneously hypertensive stroke-prone rats through mitochondrial protection.

The simultaneous presence of cardiac and renal diseases is a pathological condition that leads to increased morbidity and mortality. Several lines of evidence have suggested that lipid dysmetabolism and mitochondrial dysfunction are pathways involved in the pathological processes affecting the heart and kidney. In the salt-loaded spontaneously hypertensive stroke-prone rat (SHRSP), a model of cardiac hypertrophy and nephropathy that shows mitochondrial alterations in the myocardium, we evaluated the cardiorenal effects of fenofibrate, a peroxisome proliferator-activated receptor alpha (PPARα) agonist that acts by modulating mitochondrial and peroxisomal fatty acid oxidation. Male SHRSPs aged 6-7 weeks were divided in three groups: standard diet (n = 6), Japanese diet with vehicle (n = 6), and Japanese diet with fenofibrate 150 mg/kg/day (n = 6) for 5 weeks. Cardiac and renal functions were assessed in vivo by MRI, ultrasonography, and biochemical assays. Mitochondria were investigated by transmission electron microscopy, succinate dehydrogenase (SDH) activity, and gene expression analysis. Fenofibrate attenuated cardiac hypertrophy, as evidenced by histological and MRI analyses, and protected the kidneys, preventing morphological alterations, changes in arterial blood flow velocity, and increases in 24-h proteinuria. Cardiorenal inflammation, oxidative stress, and cellular senescence were also inhibited by fenofibrate. In salt-loaded SHRSPs, we observed severe morphological mitochondrial alterations, reduced SDH activity, and down-regulation of genes regulating mitochondrial fatty-acid oxidation (i.e. PPARα, SIRT3, and Acadm). These changes were counteracted by fenofibrate. In vitro, a direct protective effect of fenofibrate on mitochondrial membrane potential was observed in albumin-stimulated NRK-52E renal tubular epithelial cells. The results suggest that the cardiorenal protective effects of fenofibrate in young male salt-loaded SHRSPs are explained by its capacity to preserve mitochondrial function.

Intermittent negative pressure applied to the lower limb increases foot macrocirculatory and microcirculatory blood flow pulsatility in people with spinal cord injury.

Experimental prestudy and poststudy. Examine the acute effects of intermittent negative pressure (INP) applied to the lower limb on foot circulation in people with spinal cord injuries (SCIs). Vascular laboratory, Oslo University Hospital. Twenty-four people with SCI (median age 59 years, range 29-74) were exposed to lower leg INP (-40 mm Hg) using an air-tight pressure chamber connected to an INP generator. The contralateral leg was placed outside the pressure chamber. We continuously measured arterial blood flow velocity (ultrasound Doppler), skin blood flow (laser Doppler), skin temperature of the dorsum of the foot, heart rate (ECG) and systemic blood pressure (Finometer) during 5-min baseline (atmospheric pressure), followed by 10-min INP (alternating 10 s -40 mm Hg and 7 s atmospheric pressure), and 5-min post-INP (atmospheric pressure). Skin blood flow was measured on the foot placed outside the pressure chamber. A mixed effects regression model was applied to estimate the effect of INP on blood flow. To quantify flow fluctuations, we calculated cumulative up-and-down changes in arterial blood flow velocity per minute. Flow fluctuations increased during INP compared to baseline [32.3 cm/s/min (95% CI 26.9 to 37.7) vs. 15.2 cm/s/min (95% CI 9.8 to 20.6), P < 0.001]. Peak blood flow velocity and skin blood flow was reached 2-3 s after the onset of negative pressure and increased 33% (95% CI 16 to 46, P < 0.001) and 11% (95% CI -4.1 to 60, P = 0.14) above baseline, respectively. INP induced increased foot arterial blood flow fluctuations compared to baseline. The Norwegian Research Council provided funding to Otivio (grant: 241589).

Changes in Blood Flow Velocity of the Middle Cerebral Artery After Carotid Endarterectomy: Daily Assessment with Transcranial Color-Coded Sonography.

Hyperperfusion syndrome (HPS) is a well-known complication of carotid endarterectomy (CEA) warranting repeatable inexpensive monitoring. Transcranial color-coded sonography (TCCS) may provide a potential modality for such monitoring, but little is known about TCCS trends after CEA. Between January 2016 and February 2017, we prospectively included patients with CEA at our institute in this study. TCCS was performed preoperatively and repeated daily from the operation day until postoperative day (POD) 7. Daily trends in mean flow velocity (MFV) at the M1 portion of the middle cerebral artery were compared between patients with and without HPS. Among 35 patients with CEA, daily TCCS monitoring was performed in 18 patients (mean age ± SD, 72 ± 7 years; male/female, 17:1). Among these 18 patients, 3 had probable HPS. On POD 0, MFV of the 18 patients showed a 32% increase from the initial preoperative value (from 52.5 to 69.4 cm/s, P= 0.0013). This increased MFV lasted for several days and recovered gradually by POD 7. Patients with probable HPS demonstrated a trend to higher MFV than those without; however, the difference was below the significance level. We used daily TCCS after CEA to depict cerebral blood flow changes after CEA in our cohort. This technique may be useful both for the detection and prevention of HPS.

The effects of tapering and artery wall stiffness on treatments for Coarctation of the Aorta

Coarctation of the Aorta is a congenital narrowing of the aorta. Two commonly used treatments are resection and end-to-end anastomosis, and stent placements. We simulate blood flow through one-dimensional models of aortas. Different artery stiffnesses, due to treatments, are included in our model, and used to compare blood flow properties in the treated aortas. We expand our previously published model to include the natural tapering of aortas. We look at change in aorta wall radius, blood pressure and blood flow velocity, and find that, of the two treatments, the resection and end-to-end anastomosis treatment more closely matches healthy aortas.

Blunted cerebrovascular response is associated with elevated beta-amyloid

The goal of this study was to explore the association of beta-amyloid accumulation and cerebrovascular response (CVR) in cognitively normal older adults. Beta-amyloid accumulation was characterized with [18F] Florbetapir positron emission tomography scans. CVR was calculated as middle cerebral artery blood flow velocity change from rest to moderate intensity exercise. We found that individuals with elevated beta-amyloid aggregation had a blunted CVR (n = 25, age 70.1 ± 4.8; 3.3 ± 3.7 cm/s) compared to non-elevated individuals (n = 45, age 72.0 ± 4.9; 7.2 ± 5.0 cm/s, p < 0.001). Further, greater beta-amyloid burden was linearly associated with less CVR across all participants (b = −11.7, p < 0.001). Greater CVR and less beta-amyloid burden were associated with processing speed (p < 0.05). This study is the first to show that CVR from rest to exercise is blunted across increased global beta-amyloid burden.

Cardiac cycle-induced EPI time series fluctuations in the brain: Their temporal shifts, inflow effects and T2∗ fluctuations

The cardiac-induced arterial pressure wave causes changes in cerebral blood flow velocities and volumes that affect the signals in echo-planar imaging (EPI). Using single-echo EPI time series data, acquired fast enough to unalias the cardiac frequency, we found that the cardiac cycle-induced signal fluctuations are delayed differentially in different brain regions. When referenced to the time series in larger arterial structures, the cortical voxels are only minimally shifted but significant shifts are observed in subcortical areas. Using double-echo EPI data we mapped the voxels’ “signal at zero echo time”, S0, and apparent T2∗ over the cardiac cycle. S0 pulsatility was maximised for voxels with a cardiac cycle-induced timing that was close to the arterial structures and is likely explained by enhanced inflow effects in the cortical areas compared to subcortical areas. Interestingly a consistent T2∗ waveform over the cardiac cycle was observed in all voxels with average amplitude ranges between 0.3-0.55% in grey matter and 0.15–0.22% in white matter. The timing of the T2∗ waveforms suggests a partial volume fluctuation where arteriolar blood volume changes are counterbalanced by changes in CSF volumes.

Reproducibility of task activation using the Addenbrooke’s cognitive examination in healthy controls: A functional Transcranial Doppler ultrasonography study

IntroductionCerebral blood flow velocity (CBFv) changes occurring with cognitive stimulation can be measured by Transcranial Doppler ultrasonography (TCD). The aim of this study was to assess the reproducibility of CBFv changes to the Addenbrooke’s cognitive examination (ACE-III). New method13 volunteers underwent bilateral TCD (middle cerebral artery), continuous heart rate (HR, 3-lead ECG, Finometer), beat-to-beat mean arterial pressure (MAP, Finometer), and end-tidal CO2 (ETCO2, capnography). After 5min baseline, all ACE-III tasks were performed in 3 domains (A/B/C). Data presented are population CBFv peak normalised changes and area under the curve (AUC). Statistical analysis was by 2-way repeated measures (ANOVA), intra-class correlation coefficient (ICC), standard error of measurement (SEM) and coefficient of variation (CV). Results12 bilateral data sets were obtained (10 right hand dominant, 6 female). Baseline parameters (MAP, HR, ETCO2) did not differ between visits. All tasks increased CBFv. Only domain A on AUC analysis differed significantly on ANOVA, and one task on post hoc testing (p <0.05). ICC values were poor (<0.4) for most tasks, but 3 tasks produced more consistent results on AUC and peak CBFv analysis (range ICC: 0.15–0.73, peak CV: 16.2–56.1(%), AUC CV: 23.2–60.2(%), peak SEM: 2.5–6.0 (%), AUC SEM: 21.8–135.8 (%*s). Comparison with existing methodsThis is the first study to examine reproducibility of CBFv changes to a complete cognitive assessment tool. ConclusionsReproducibility of CBFv measurements to the ACE-III was variable. AUC may provide more reliable estimates than peak CBFv responses. These data need validating in patient populations.

Retinal Blood Flow Velocity Change in Parafoveal Capillary after Topical Tafluprost Treatment in Eyes with Primary Open-angle Glaucoma

Although ocular circulation at the retina and optic disc is known to be associated with the pathology of glaucoma, direct measurement of blood flow velocity has been difficult to obtain. This prospective observational study enrolled 11 consecutive patients with treatment-naïve primary open-angle glaucoma (POAG) and 11 healthy subjects, and the effects of topical tafluprost treatment on ocular circulation were examined at baseline and at 1, 4, and 12 weeks after initiating treatment with topical tafluprost on POAG patients using multiple modalities, which include adaptive optics scanning laser ophthalmoscopy (AOSLO). Baseline mean intraocular pressure (IOP) was significantly higher and mean parafoveal blood flow velocity (pBFV) was significantly lower in POAG eyes than in healthy eyes. Mean IOP was significantly decreased (1 week, −19.1%; 4 weeks, −17.7%; and 12 weeks, −23.5%; all P < 0.001) and mean pBFV was significantly increased from the baseline at all follow-up periods after initiating treatment (1 week, 14.9%, P = 0.007; 4 weeks, 21.3%, P < 0.001; and 12 weeks, 14.3%, P = 0.002). These results reveal that tafluprost may not only lower IOP but may also improve retinal circulation in POAG eyes and AOSLO may be useful to evaluate retinal circulatory change after treatment.

Relationship between heart rate excursion and apnea duration in patients with Obstructive Sleep Apnea.

Obstructive Sleep Apnea (OSA) is a sleep disorder with a high prevalence in the general population. It is a risk factor for many cardiovascular diseases, and an independent risk factor for cerebrovascular diseases such as stroke. After an apnea episode, both arterial blood pressure and cerebral blood flow velocity change in function of the apnea duration (AD). We hypothesized that the relative excursion in heart rate (AHR), defined as the percentage difference between the maximum and the minimum heart rate values associated to an obstructive apnea event, is also related to AD. In this work we studied the relationship between apnea-related AHR and AD in a population of eight patients with severe OSA. AHR and AD showed a moderate but statistically significant correlation (p <; 0.0001) in a total of 1454 obstructive apneas analyzed. The average heart rate excursion for apneas with AD ≥ 30s (ΔHR = 31.29 ± 6.64%) was significantly greater (p = 0.0002) than for apneas with AD ∈ [10,20)s (ΔHR = 18.14±3.08%). We also observed that patients with similar Apnea-Hypopnea Index (AHI) may exhibit remarkably different distributions of AHR and AD, and that patients with a high AHI need not have a higher average AHR than others with a lower severity index. We conclude that the overall apnea-induced heart rate excursion is partially explained by the duration of apnoeic episodes, and it may be a simple measure of the cardiovascular stress associated with OSA that is not directly reflected in the AHI.

Random squat/stand maneuvers: a novel approach for assessment of dynamic cerebral autoregulation?

Squat/stand maneuvers (SSM) have been used to assess dynamic cerebral autoregulation (dCA), but always at a fixed frequency (FF). This study aimed to assess the use of random-frequency (RF) SSMs as a stimulus for measuring dCA and determine the reproducibility of FF and RFSSMs. Twenty-nine healthy volunteers [19 male, mean age 23.0 (4.9) yr] completed the study; 11 returned for a repeat visit (median 45 days). Heart rate, beat-to-beat blood pressure, middle cerebral artery (MCA) blood flow velocity, end-tidal CO2, and angle of the squat movement were measured. Subjects underwent four recordings: 5 min sitting, 5 min standing, FFSSMs (0.05Hz), and RFSSMs. Subjects were asked to rate the degree of exertion experienced while performing these maneuvers. Twenty-nine subjects completed the protocol; nine data sets were deemed unsuitable for further analysis. Mean ARI of 6.21 (1.04) while standing was significantly greater than during the SSMs (P < 0.01), with mean (SD) ARI during the FF and RFSSMs being 5.16 (1.43) and 5.37 (1.21), respectively. However, no significant difference was found between the ARI estimates from the two SSMs (P = 0.856) or for each of the four recordings between the two visits (P = 0.645). RFSSMs were found to be significantly less tiring than FFSSMs (P < 0.01). In conclusion, RFSSMs are an effective and noninvasive method of assessing dCA. There is no difference in the ARI estimates in comparison with FFSSMs. Although FFSSMs have been well tolerated previously, RFSSMs are preferred by healthy subjects and thus may be better tolerated by a patient population in a clinical setting.NEW & NOTEWORTHY RFSSMs provided comparable estimates of autoregulatory indices to FFSSMs. Instead of point estimates at the driven frequency, RFSSMs generate a broader power spectrum of changes in arterial blood pressure and cerebral blood flow velocity, allowing direct comparison with spontaneous fluctuations through transfer function analysis. Moreover, random-frequency SSMs are preferred by participants. They are a novel tool by which larger blood pressure oscillations can be elicited for the reliable measurement of dynamic cerebral autoregulation.

Blood flow velocity and thickness of the choroid in a patient with chorioretinopathy associated with ocular blunt trauma

BackgroundChoroidal circulation hemodynamics in eyes with ocular blunt trauma has not been quantitatively examined yet. We quantitatively examined changes in choroidal blood flow velocity and thickness at the lesion site using laser speckle flowgraphy (LSFG) and enhanced depth imaging optical coherence tomography (EDI-OCT) in a patient with chorioretinopathy associated with ocular blunt trauma.Case presentationA 13-year-old boy developed a chorioretinal lesion with pigmentation extending from the optic disc to the superotemporal side in the right eye after ocular blunt trauma. The patient’s best-corrected visual acuity (BCVA) was 0.2 in the right eye. Indocyanine green angiography showed hypofluorescence from the initial phase, with a decrease of mean blur rate (MBR) on LSFG color map, which corresponded to the chorioretinal lesion. The BCVA and foveal outer retinal morphologic abnormality spontaneously improved during follow-up. MBR and choroidal thickness increased by 23–31% and 13–17 μm at the lesion site and by 11–22% and 33–42 μm at the fovea, respectively, during the 6-month follow-up period after baseline measurements in the affected eye. In contrast, these parameters showed little or no changes at the normal retinal site in the affected eye and the fovea in the fellow eye.ConclusionsCurrent data revealed that both blood flow velocity and thickness in the choroid at the lesion site decreased in the acute stage and subsequently increased together with improvements in visual function and outer retinal morphology. These results suggest that LSFG and EDI-OCT may be useful indices that can noninvasively evaluate activity of choroidal involvement in ocular blunt trauma-associated chorioretinopathy.

Transcranial Doppler Identification of Neurologic Injury during Pediatric Extracorporeal Membrane Oxygenation Therapy

We used transcranial Doppler to examine changes in cerebral blood flow velocity in children treated with extracorporeal membrane oxygenation. We examined the association between those changes and radiologic, electroencephalographic, and clinical evidence of neurologic injury. This was a retrospective review and prospective observational study of patients 18 years old and younger at a single university children's hospital. Transcranial Doppler studies were obtained every other day during the first 7 days of extracorporeal membrane oxygenation, and 1 additional study following decannulation, in conjunction with serial neurologic examinations, brain imaging, and 6- to 12-month follow-up. The study included 27 patients, the majority (26) receiving veno-arterial extracorporeal membrane oxygenation. Transcranial Doppler velocities during extracorporeal membrane oxygenation were significantly lower than published values for age-matched healthy and critically ill children across different cerebral arteries. Neonates younger than 10 days had higher velocities than expected. Blood flow velocity increased after extracorporeal membrane oxygenation decannulation and was comparable with age-matched critically ill children. There was no significant association between velocity measurements of individual arteries and acute neurologic injury as defined by either abnormal neurologic examination, seizures during admission, or poor pediatric cerebral performance category. However, case analysis identified several patients with regional and global increases in velocities that corresponded to neurologic injury including stroke and seizures. Cerebral blood flow velocities during extracorporeal membrane oxygenation deviate from age-specific normal values in all major cerebral vessels and across different age groups. Global or regional elevations and asymmetries in flow velocity may suggest impending neurologic injury.

Measurement of Blood Flow Velocity in the Middle Cerebral Artery During Spontaneous Migraine Attacks: A Systematic Review.

To assess the evidence for blood flow velocity changes in the middle cerebral artery during and outside of spontaneous migraine attacks. A systematic literature search on PubMed was performed and reference lists of assessed articles to identify studies on spontaneous migraine attacks that used transcranial Doppler on the middle cerebral artery with comparisons to interictal measurements were reviewed. Studies on non-spontaneous attacks and intervention studies were excluded. A total of 17 original articles reporting blood flow velocity values in the middle cerebral artery using transcranial Doppler in migraine patients both with and without aura were identified. A total of 24 subgroups (ie, migraine patients without aura = 11, migraine patients with aura = 9, and mixed = 4) of migraine patients were investigated during and outside spontaneous migraine attacks in the 17 studies. No change was reported in 15 subgroups (63%), while decreased blood flow velocity was found in 8 subgroups (33%) and increased blood flow velocity was found in one study (4%). Exploratory analysis revealed that studies showing decreased blood flow velocity were carried out earlier after onset of attack (mean time, 4.1 h) compared with those showing no change (mean time, 6.0 h). Overall, spontaneous migraine attacks are not accompanied by blood flow velocity changes in the middle cerebral artery. However, explorative analyses on the time from attack onset to examination revealed side-specific attack-related decrease in blood flow velocity in the early, but not late phases. This is the first systematic review focusing on the flow changes in the middle cerebral artery of spontaneous migraine attacks. Future studies should focus on the early blood flow velocity changes in migraine attacks.

Posttransfusion Increase of Hematocrit per se Does Not Improve Circulatory Oxygen Delivery due to Increased Blood Viscosity.

Blood transfusion is used to treat acute anemia with the goal of increasing blood oxygen-carrying capacity as determined by hematocrit (Hct) and oxygen delivery (DO2). However, increasing Hct also increases blood viscosity, which may thus lower DO2 if the arterial circulation is a rigid hydraulic system as the resistance to blood flow will increase. The net effect of transfusion on DO2 in this system can be analyzed by using the relationship between Hct and systemic blood viscosity of circulating blood at the posttransfusion Hct to calculate DO2 and comparing this value with pretransfusion DO2. We hypothesized that increasing Hct would increase DO2 and tested our hypothesis by mathematically modeling DO2 in the circulation. Calculations were made assuming a normal cardiac output (5 L/min) with degrees of anemia ranging from 5% to 80% Hct deficit. We analyzed the effects of transfusing 0.5 or more units of 300 cc of packed red blood cells (PRBCs) at an Hct of 65% and calculated microcirculatory DO2 after accounting for increased blood viscosity and assuming no change in blood pressure. Our model accounts for O2 diffusion out of the circulation before blood arriving to the nutritional circulation and for changes in blood flow velocity. The immediate posttransfusion DO2 was also compared with DO2 after the transient increase in volume due to transfusion has subsided. Blood transfusion of up to 3 units of PRBCs increased DO2 when Hct (or hemoglobin) was 60% lower than normal, but did not increase DO2 when administered before this threshold. After accounting for the effect of increasing blood viscosity on blood flow owing to increasing Hct, we found in a mathematical simulation of DO2 that transfusion of up to 3 units of PRBCs does not increase DO2, unless anemia is the result of an Hct deficit greater than 60%. Observations that transfusions occasionally result in clinical improvement suggest that other mechanisms possibly related to increased blood viscosity may compensate for the absence of increase in DO2.

Executive Network Activation is Linked to Walking Speed in Older Adults: Functional MRI and TCD Ultrasound Evidence From the MOBILIZE Boston Study.

Changes in cerebral blood flow velocity (CBF) in response to a cognitive task (task-related ΔCBF) have been shown by Transcranial Doppler ultrasonography (TCD) to be reduced in slow walkers. However, it is unknown whether reduced task-related ΔCBF is associated with reduced neural activity in specific brain regions, as measured by blood-oxygen-level dependent (BOLD) functional magnetic resonance imaging (fMRI). We assessed the regional changes in neural activity associated with reduced middle cerebral artery (MCA) task-related ΔCBF to an executive task and slow walking speed in 67 community-dwelling older adults from the MOBILIZE Boston Study. Participants underwent walking assessments and TCD ultrasonography measures of MCA ΔCBF during the n-back task of executive function. A subset of participants (n = 27) completed the same task during fMRI. Individual BOLD activation maps for the n-back task were correlated with TCD measures and network-level averages were associated with TCD and preferred walking speed. Participants with diminished task-related ΔCBF walked more slowly (β = .39, p = .001). fMRI revealed significant associations between task-related ΔCBF and regional BOLD activation in several brain regions/networks supplied by the MCA. Of these regions and networks, those within the executive network were most strongly associated with walking speed (β = .36, p = .01). Task-related ΔCBF during an executive function task is related to activation in several neural networks and impairment in the ability to recruit the executive network in particular is associated with slow walking speed in older adults.

Continuous-mode 448 kHz capacitive resistive monopolar radiofrequency induces greater deep blood flow changes compared to pulsed mode shortwave: a crossover study in healthy adults

Aims: Radiofrequency-based electrophysical agents (EPAs) have been used in therapy practice over several decades (e.g. shortwave therapies). Currently, there is insufficient evidence supporting such EPAs operating below shortwave frequencies. This laboratory-based study investigated the deep physiological effects of 448 kHz capacitive resistive monopolar radiofrequency (CRMRF) and compared them to pulsed shortwave therapy (PSWT).Methods: In a randomized crossover study, 17 healthy volunteers initially received four treatment conditions: high, low and placebo dose conditions receiving 15-min CRMRF treatment and a control condition receiving no intervention. Fifteen participants additionally received high-dose PSWT as fifth condition, for comparison. Pre- and post-treatment measurements of deep blood flow and tissue extensibility were obtained using Doppler ultrasound and sonoelastography. Group data were compared using analysis of variance model. Statistical significance was set at p ≤ .05, 0.8 power, and 95% confidence interval.Results: Significant increases in volume and intensity of deep blood flow were obtained with CRMRF over placebo, control (p = .003) and PSWT (p < .001). No significant changes in blood flow velocity or tissue extensibility were noted for any condition.Conclusions: Deep blood flow changes with CRMRF were more pronounced than that with PSWT, placebo or control. Potential greater therapeutic benefits need to be confirmed with comparative clinical studies.

Orthostatic dizziness in Parkinson's disease is attributed to cerebral hypoperfusion: A transcranial doppler study.

Orthostatic hypotension (OH) is controversially regarded as the cause of orthostatic dizziness in Parkinson's disease (PD). We sought to evaluate whether cerebral autoregulation is an alternative cause for orthostatic dizziness in PD patients, using transcranial Doppler monitoring during head-up tilting. Forty-five PD patients with dizziness, 13 PD patients without dizziness, and 10 age-matched healthy controls were enrolled. Participants were divided into the following four groups: patients with dizziness and OH (group 1, n = 22), patients with dizziness but no OH (n = 23, group 2), patients without dizziness (n = 11, group 3), and age-matched healthy controls (n = 10, group 4). All participants underwent transcranial Doppler and blood pressure monitoring for 10 minutes during the head-up tilt test. Changes in the cerebral blood flow velocity (CBFV) in the middle cerebral artery and the mean blood pressure (mBP) within 3 minutes after head-up tilting were compared between groups. Group 1 showed a significantly higher change in mBP (-16.3 ± 10.8 mmHg) than groups 2 (-2.6 ± 4.9), 3 (-2.2 ± 3.6), or 4 (1.8 ± 6.0) (p < 0.001). However, groups 3 (4.6 ± 3.0 cm/s) and 4 (-4.2 ± 2.5) showed a significantly smaller change in CBFV than groups 1 (-9.0 ± 4.2) and 2 (-8.1 ± 5.1) (p < 0.01). Our results suggest that cerebral hypoperfusion contributes to dizziness in PD patients despite a lack of OH. Transcranial Doppler monitoring during head-up tilting may be a useful tool for evaluating dizziness in PD patients with or without OH. © 2016 Wiley Periodicals, Inc. J Clin Ultrasound 45:337-342, 2017.

Test-Retest Reliability of Measuring the Vertebral Arterial Blood Flow Velocity in People With Cervicogenic Dizziness

ObjectivesThe purpose of this study was to determine the within-session and between-sessions reliability of measuring the vertebral artery blood flow velocities in people with cervicogenic dizziness using Doppler ultrasound at both upper and lower cervical levels. MethodsOutcome measures were taken on 2 occasions 3 weeks apart with no active treatment provided in between the assessments on 12 participants. Pulsed-wave Doppler ultrasound was used to quantify time-averaged mean velocities through the vertebral artery at upper cervical (C0-1) and lower cervical vertebrae (C5-6). The clinical outcome measures were also recorded in people with cervicogenic dizziness. The intraclass correlation coefficient (ICC) was used to determine the within-session and between-session repeatability. Paired t test was used to determine the differences in the time-averaged mean velocities of blood flow at the same site of the vertebral artery and the clinical outcome measures in 2 sessions 3 weeks apart. ResultsIn people with cervicogenic dizziness, there was no significant change in both clinical outcome measures and the time-averaged mean velocities when the patients were measured 3 weeks apart (P > .05). This study identified good within-session (ICC: 0.903-0.967) and between-session (ICC: 0.922-0.984) repeatability in measuring the vertical blood flow velocities in patients with cervicogenic dizziness when the clinical outcome measures were unchanged. ConclusionsThis study supports the use of Doppler ultrasound to identify changes in mean vertebral arterial blood flow velocities before and after intervention in people with cervicogenic dizziness in future studies.

Assessment of Cutaneous Microcirculation Autoregulation with Phase and Linear Based Eulerian Video Magnification

IntroductionThe identification of low frequency variations in blood pressure recordings date back to the mid‐1800's. The mechanism for the low frequency oscillation is associated with intrinsic myogenic activity of smooth muscle cells in resistance arteries. Therefore, local metabolic demand modulates blood flow distribution. Non‐invasive assessment of the microcirculation in dermatology, diabetes, skin‐graft, and burn‐injury patients could facilitate assessment of therapeutic interventions. Eulerian Video Magnification (EVM) software was developed by the Massachusetts Institute of Technology (MIT) to magnify subtle changes in motion and color in video recordings. Using this technology, magnification of a video recording may reveal local changes in the cutaneous human microcirculation.HypothesisWe hypothesize that EVM can be used to assess oscillations in cutaneous blood flow velocity.MethodsIRB approval was obtained to acquire physiological data from healthy graduate students (N = 10). Tissue Doppler was used to measure local changes in blood flow velocity on the forehead. Heart rate was assessed with an ECG and subjects breathed in time to a metronome (15 breaths/min) to normalize the effect of ventilation. Videos were processed using MIT's EVM Matlab code to magnify motion (Phase), or color &amp; motion (Linear). All videos were magnified in the frequency range of interest (0.067–1.67 Hz; 4–100 cycles/min) to enhance human physiological frequencies. Gain was set to 50%; and a Gaussian filter was set to level 4. Phase magnification used a pyramid filtering scheme with octaves (1, ½, ¼) to specify the number of times the video is filtered; while linear magnification utilized chrominance attenuation to reduce color changes created by the magnification process. Red, green, and blue color spectrums extracted from magnified videos were analyzed with a Fast Fourier Transform (FFT) to identify magnified frequencies and power.ResultsPhase magnification (motion) and corresponding FFTs suggest strong correlations to heart rate and respiration rate but not tissue Doppler blood flow. On the other hand, linear magnification (color) and accompanying FFTs were strongly correlated to heart rate (r = 0.987; p = 0.001), respiration rate (r = 0.741; p = 0.014), and local tissue Doppler recordings (r = 0.945; p = 0.001).ConclusionThese preliminary data demonstrate that a video recording of a human subject can be magnified with EVM to assess heart rate, respiration rate, and regional blood flow velocity oscillations in the cutaneous microcirculation. EVM may be a useful non‐invasive modality to evaluate changes in microcirculation autoregulation in human subjects.Support or Funding InformationMidwestern University, Chicago College of Osteopathic Medicine, College of Health Sciences