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Context: Resistance training with blood flow restriction (BFR) has increased in clinical rehabilitation due to the substantial benefits observed in augmenting muscle mass and strength using low loads. However, there is a great variability of training pressures for clinical populations as well as methods to estimate it. The aim of this study was to estimate the percentage of maximal BFR that could result by applying different methodologies based on arbitrary or individual occlusion levels using a cuff width between 9 and 13 cm. Design: A secondary analysis was performed on the combined databases of 2 previous larger studies using BFR training. Methods: To estimate these percentages, the occlusion values needed to reach complete BFR (100% limb occlusion pressure [LOP]) were estimated by Doppler ultrasound. Seventy-five participants (age 24.32 [4.86] y; weight: 78.51 [14.74] kg; height: 1.77 [0.09] m) were enrolled in the laboratory study for measuring LOP in the thigh, arm, or calf. Results: When arbitrary values of restriction are applied, a supra-occlusive LOP between 120% and 190% LOP may result. Furthermore, the application of 130% resting brachial systolic blood pressure creates a similar occlusive stimulus as 100% LOP. Conclusions: Methods using 100 mm Hg and the resting brachial systolic blood pressure could represent the safest application prescriptions as they resulted in applied pressures between 60% and 80% LOP. One hundred thirty percent of the resting brachial systolic blood pressure could be used to indirectly estimate 100% LOP at cuff widths between 9 and 13 cm. Finally, methodologies that use standard values of 200 and, 300 mm Hg far exceed LOP and may carry additional risk during BFR exercise. [ABSTRACT FROM AUTHOR]

In this study, the growth and rupture of plaque were investigated to predict the development of carotid atherosclerosis and plaque. Realistic 3D models of multi-component plaque and carotid artery were established in healthy, mild, moderate, and severe stenosis. Fluid–structure interaction (FSI) simulations were performed on these models, and the wall shear stress (WSS), time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), relative residence time (RRT), and wall tensile stress (WTS) in a natural cardiac cycle were analyzed to assess the epidermal rupture, growth tendency, and internal rupture of plaques in a natural state. Results show that in severe stenosis, the WSS at the stenosis sites exceeds the threshold of rupture during almost the entire cardiac cycle, thus causing an epidermal injury, bringing about plaque detachment and thrombosis. TAWSS decreased and OSI and RRT increased in the bifurcation region and the downstream region of the plaque. The deposition is more likely to occur in these regions. A higher degree of stenosis will increase the OSI and RRT in the downstream region of the plaque, leading to continuous deterioration of the plaque, while the degree of stenosis has little effect on the upstream region of the plaque. The fibrous cap is the starting point for rupture within the plaque, and calcification increases the stress on the fibrous cap, thereby increasing the risk of rupture. [ABSTRACT FROM AUTHOR]

The article focuses on the birth and subsequent health concerns of a newborn delivered to a mother with an uncomplicated prenatal course. Topics include the infant's feeding regimen, initial discharge with a presumptive diagnosis, and his presentation to the emergency department with symptoms such as fever and hematochezia.

Cardiovascular diseases can be an emerging complication in cystic fibrosis (CF), as the median life expectancy has improved considerably. The objective of this study was to compare vascular, hemodynamic parameters and arterial stiffness in adult CF patients with healthy participants pared by sex and age, and to assess the factors associated with arterial stiffness in the CF group. This is a cross-sectional observational study. The evaluation of cardiovascular parameters was performed non-invasively using Mobil-O-Graph. 36 individuals with CF and 35 controls were evaluated. The mean arterial pressure (96.71 ± 10.98 versus 88.61 ± 7.40 mmHg, p = 0.0005), cardiac output (4.86 ± 0.57 versus 4.48 ± 0.44 L/min, p = 0.002) and systolic volume (64.30 ± 11.91 versus 49.02 ± 9.31 ml, p < 0.0001) were significantly lower in the CF group. The heart rate was higher in the CF when compared to the control (77.18 ± 10.47 versus 93.56 ± 14.57 bpm, p < 0.0001). The augmentation index (AIx@75) was higher in the CF than control (29.94 ± 9.37 versus 16.52 ± 7.179%, p < 0.0001). In the multivariate model controlled by body mass index and Forced Expiratory Volume in the first second, central systolic blood pressure and reflection coefficient directly related to AIx@75. Negatively related to AIx@75 were age and systolic volume. The adjusted determination coefficient was 87.40%. Individuals with CF presented lower arterial blood pressures and changes in cardiac function with lower stroke volume and cardiac output. The AIx@75, an indirect index of arterial stiffness and direct index of left ventricular overload, is increased in this population. The subclinical findings suggest the need for earlier cardiovascular assessment in this population due to increased risks of cardiovascular disease. [ABSTRACT FROM AUTHOR]

Background: High-risk non-ST-elevation myocardial infarction (NSTEMI) patients' optimal timing for percutaneous coronary intervention (PCI) is debated despite the recommendation for early invasive revascularization. This study aimed to compare outcomes of NSTEMI patients without hemodynamic instability undergoing very early invasive strategy (VEIS, ≤ 12 hours) versus delayed invasive strategy (DIS, >12 hours). Methods: Excluding urgent indications for PCI including initial systolic blood pressure under 90 mmHg, ventricular arrhythmia, or Killip class IV, 4,733 NSTEMI patients were recruited from the Korea Acute Myocardial Infarction Registry-National Institutes of Health (KAMIR-NIH). Patients were divided into low and high- global registry of acute coronary events risk score risk score (GRS) groups based on 140. Both groups were then categorized into VEIS and DIS. Clinical outcomes, including all-cause death (ACD), cardiac death (CD), recurrent MI, and cerebrovascular accident at 12 months, were evaluated. Results: Among 4,733 NSTEMI patients, 62% had low GRS, and 38% had high GRS. The proportions of VEIS and DIS were 43% vs. 57% in the low GRS group and 47% vs. 53% in the high GRS group. In the low GRS group, VEIS and DIS demonstrated similar outcomes; however, in the high GRS group, VEIS exhibited worse ACD outcomes compared to DIS (HR = 1.46, P = 0.003). The adverse effect of VEIS was consistent with propensity score matched analysis (HR = 1.34, P = 0.042). Conclusion: VEIS yielded worse outcomes than DIS in high-risk NSTEMI patients without hemodynamic instability in real-world practice. [ABSTRACT FROM AUTHOR]

Background: Significant hemodynamic changes occur during liver transplantation, emphasizing the importance of precious and continuous monitoring of cardiac output, cardiac index, and other parameters. Although the monitoring of cardiac output by pulse indicator continuous cardiac output (PiCCO) was statistically homogeneous compared to the clinical gold standard pulmonary artery catheterization (PAC) in previous studies of liver transplantation, there are fewer statistical methods for the assessment of its conclusions, and a lack of comparisons of other hemodynamic parameters (e.g., SVRI, systemic vascular resistance index). Some studies have also concluded that the agreement between PiCCO and PAC is not good enough. Overall, there are no uniform conclusions regarding the agreement between PiCCO and PAC in previous studies. This study evaluates the agreement and trending ability of relevant hemodynamic parameters obtained with PiCCO compared to the clinical gold standard PAC from multiple perspectives, employing various statistical methods. Methods: Fifty-two liver transplantation patients were included. Cardiac output (CO), cardiac index (CI), SVRI and stroke volume index (SVI) values were monitored at eight time points using both PiCCO and PAC. The results were analyzed by Bland-Altman analysis, Passing-bablok regression, intra-class correlation coefficient (ICC), 4-quadrant plot, polar plot, and trend interchangeability method (TIM). Results: The Bland-Altman analysis revealed high percentage errors for PiCCO: 54.06% for CO, 52.70% for CI, 62.18% for SVRI, and 51.97% for SVI, indicating poor accuracy. While Passing-Bablok plots showed favorable agreement for SVRI overall and during various phases, the agreement for other parameters was less satisfactory. The ICC results confirmed good overall agreement between the two devices across most parameters, except for SVRI during the new liver phase, which showed poor agreement. Additionally, four-quadrant and polar plot analyses indicated that all agreement rate values fell below the clinically acceptable threshold of over 90%, and all angular deviation values exceeded ± 5°, demonstrating that PiCCO is unable to meet the acceptable trends. Using the TIM, the interchangeability rates were found to be quite low: 20% for CO and CI, 16% for SVRI, and 13% for SVI. Conclusions: Our study revealed notable disparities in absolute values of CO, CI, SVRI and SVI between PiCCO and PAC in intraoperative liver transplant settings, notably during the neohepatic phase where errors were particularly pronounced. Consequently, these findings highlight the need for careful consideration of PiCCO's advantages and disadvantages in liver transplantation scenarios, including its multiple parameters (such as the encompassing extravascular lung water index), against its limited correlation with PAC. [ABSTRACT FROM AUTHOR]

Introduction: Mental fatigue is an early and enduring symptom in persons with autoimmune disease particularly multiple sclerosis (MS). Neuromodulation has emerged as a potential treatment although optimal cortical targets have yet to be determined. We aimed to examine cortical hemodynamic responses within bilateral dorsolateral prefrontal cortex (dlPFC) and frontopolar areas during single and dual cognitive tasks in persons with MS-related fatigue compared to matched controls. Methods: We recruited persons (15 MS and 12 age- and sex-matched controls) who did not have physical or cognitive impairment and were free from depressive symptoms. Functional near infrared spectroscopy (fNIRS) registered hemodynamic responses during the tasks. We calculated oxyhemoglobin peak, time-to-peak, coherence between channels (a potential marker of neurovascular coupling) and functional connectivity (z-score). Results: In MS, dlPFC demonstrated disrupted hemodynamic coherence during both single and dual tasks, as evidenced by non-significant and negative correlations between fNIRS channels. In MS, reduced coherence occurred in left dorsolateral PFC during the single task but occurred bilaterally as the task became more challenging. Functional connectivity was lower during dual compared to single tasks in the right dorsolateral PFC in both groups. Lower z-score was related to greater feelings of fatigue. Peak and time-to-peak hemodynamic response did not differ between groups or tasks. Conclusions: Hemodynamic responses were inconsistent and disrupted in people with MS experiencing mental fatigue, which worsened as the task became more challenging. Our findings point to dlPFC, but not frontopolar areas, as a potential target for neuromodulation to treat cognitive fatigue. [ABSTRACT FROM AUTHOR]

The mechanisms behind intracranial aneurysm formation and rupture are not fully understood, with factors such as location, patient demographics, and hemodynamics playing a role. Additionally, the significance of anatomical features like blebs in ruptures is debated. This highlights the necessity for comprehensive research that combines patient‐specific risk factors with a detailed analysis of local hemodynamic characteristics at bleb and rupture sites. Our study analyzed 359 intracranial aneurysms from 268 patients, reconstructing patient‐specific models for hemodynamic simulations based on 3D rotational angiographic images and intraoperative videos. We identified aneurysm subregions and delineated rupture sites, characterizing blebs and their regional overlap, employing statistical comparisons across demographics, and other risk factors. This work identifies patterns in aneurysm rupture sites, predominantly at the dome, with variations across patient demographics. Hypertensive and anterior communicating artery (ACom) aneurysms showed specific rupture patterns and bleb associations, indicating two pathways: high‐flow in ACom with thin blebs at impingement sites and low‐flow, oscillatory conditions in middle cerebral artery (MCA) aneurysms fostering thick blebs. Bleb characteristics varied with gender, age, and smoking, linking rupture risks to hemodynamic factors and patient profiles. These insights enhance understanding of the hemodynamic mechanisms leading to rupture events. This analysis elucidates the role of localized hemodynamics in intracranial aneurysm rupture, challenging the emphasis on location by revealing how flow variations influence stability and risk. We identify two pathways to wall failure—high‐flow and low‐flow conditions—highlighting the complexity of aneurysm behavior. Additionally, this research advances our knowledge of how inherent patient‐specific characteristics impact these processes, which need further investigation. [ABSTRACT FROM AUTHOR]

Atrial fibrillation (AF) poses a significant risk of stroke due to thrombus formation, which primarily occurs in the left atrial appendage (LAA). Medical image‐based computational fluid dynamics (CFD) simulations can provide valuable insight into patient‐specific hemodynamics and could potentially enhance personalized assessment of thrombus risk. However, the importance of accurately representing the left atrial (LA) wall dynamics has not been fully resolved. In this study, we compared four modeling scenarios; rigid walls, a generic wall motion based on a reference motion, a semi‐generic wall motion based on patient‐specific motion, and patient‐specific wall motion based on medical images. We considered a LA geometry acquired from 4D computed tomography during AF, systematically performed convergence tests to assess the numerical accuracy of our solution strategy, and quantified the differences between the four approaches. The results revealed that wall motion had no discernible impact on LA cavity hemodynamics, nor on the markers that indicate thrombus formation. However, the flow patterns within the LAA deviated significantly in the rigid model, indicating that the assumption of rigid walls may lead to errors in the estimated risk factors. In contrast, the generic, semi‐generic, and patient‐specific cases were qualitatively similar. The results highlight the crucial role of wall motion on hemodynamics and predictors of thrombus formation, and also demonstrate the potential of using a generic motion model as a surrogate for the more complex patient‐specific motion. While the present study considered a single case, the employed CFD framework is entirely open‐source and designed for adaptability, allowing for integration of additional models and generic motions. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to compare the hemodynamic effects of remimazolam- and propofol-based total intravenous anesthesia in patients who underwent transcatheter aortic valve replacement. Methods: This was a single-center, single-blind, randomized controlled trial set at Nara Medical University, Kashihara, Japan. We included 36 patients aged ≥ 20 years scheduled to undergo elective transfemoral transcatheter aortic valve replacement (TAVR) under general anesthesia. The participants were randomly assigned to the remimazolam and propofol groups (n = 18 each). Remimazolam- or propofol-based total intravenous anesthesia was initiated at 12 mg/kg/min or 2.5 mcg/mL via target-controlled infusion, respectively, along with remifentanil. After confirming the loss of consciousness, the administration rate was adjusted using electroencephalographic monitoring. The primary outcome was the rate of arterial hypotension, defined as a mean arterial pressure < 60 mmHg, from anesthesia induction until the beginning of the surgical incision. The total doses of ephedrine and phenylephrine were also assessed. Results: During anesthesia induction, the arterial hypotension rates were 11.9% and 21.6% in the remimazolam and propofol groups, respectively (P = 0.01). The total dose of ephedrine was higher in the propofol group (14.4 mg) than in the remimazolam group (1.6 mg) (P < 0.001); however, the total dose of phenylephrine was not significantly different between the two groups (propofol 0.31 mg vs. remimazolam: 0.17 mg, P = 0.10). Conclusion: Remimazolam-based total intravenous anesthesia resulted in a lower hypotension rate than propofol-based total intravenous anesthesia during induction in patients undergoing TAVR. Remimazolam-based total intravenous anesthesia can be used safely during anesthetic induction in patients with severe aortic stenosis. [ABSTRACT FROM AUTHOR]

In the article, the authors discuss their process of developing and implementing ambulation safety checklists for hemodynamically-stable patients with pulmonary artery catheters (PAC) in the step-down unit. Also cited are the qualified staff like primary nurse, charge nurse, and resource nurse, and the potential benefits of said checklists like reducing nurse burnout, increasing physical activity in patients, and preventing deconditioning.

Organized trauma systems reduce morbidity and mortality after serious injury. Rapid transport to high-level trauma centers is ideal, but not always feasible. Thus, interhospital transfers are an important component of trauma systems. However, transferring a seriously injured patient carries the risk of worsening condition before reaching definitive care. In this study, we evaluated characteristics and outcomes of patients whose hemodynamic status worsened during the transfer process. We conducted a retrospective cohort study using data from the Pennsylvania Trauma Outcomes Study database from 2011 to 2018. Patients were included if they had a heart rate ≤ 100 and systolic blood pressure ≥ 100 at presentation to the referring hospital and were transferred within 24 h. We defined hemodynamic deterioration (HDD) as admitting heart rate > 100 or systolic blood pressure < 100 at the receiving center. We compared demographics, mechanism of injury, injury severity, management, and outcomes between patients with and without HDD using descriptive statistics and multivariable regression analysis. Of 52,919 included patients, 5331 (10.1%) had HDD. HDD patients were more often moderately-severely injured (injury severity score 9-15; 40.4% versus 39.4%, P < 0.001) and injured via motor vehicle collision (23.2% versus 16.6%, P < 0.001) or gunshot wound (2.1% versus 1.3%, P < 0.001). HDD patients more often had extremity or torso injuries and after transfer were more likely to be transferred to the intensive care unit (35% versus 28.5%, P < 0.001), go directly to surgery (8.4% versus 5.9%, P < 0.001), or interventional radiology (0.8% versus 0.3%, P < 0.001). Overall mortality in the HDD group was 4.9% versus 2.1% in the group who remained stable. These results were confirmed using multivariable analysis. Interhospital transfers are essential in trauma, but one in 10 transferred patients deteriorated hemodynamically in that process. This high-risk component of the trauma system requires close attention to the important aspects of transfer such as patient selection, pretransfer management/stabilization, and communication between facilities. [ABSTRACT FROM AUTHOR]

Female sex is a significant risk factor for pulmonary arterial hypertension (PAH), yet males with PAH have worse survival – a phenomenon referred to as the "sex paradox" in PAH. All adult PAH patients in the Pulmonary Hypertension Association Registry (PHAR) with congruent sex and gender were included. Baseline differences in demographics, hemodynamics, functional parameters, and quality of life were assessed by sex. Kaplan-Meier survival analysis was used to evaluate survival by sex. Mediation analysis was conducted with Cox proportional hazards regression by comparing the unadjusted hazard ratios for sex before and after adjustment for covariates. The plausibility of collider-stratification bias was assessed by modeling how large an unmeasured factor would have to be to generate the observed sex-based mortality differences. Subgroup analysis was performed on idiopathic and incident patients. Among the 1,891 patients included, 75% were female. Compared to men, women had less favorable hemodynamics, lower 6-minute walk distance, more PAH therapies, and worse functional class; however, sex-based differences were less pronounced when accounting for body surface area or expected variability by gender. On multivariate analysis, women had a 48% lower risk of death compared to men (Hazard Ratio 0.52, 95% Confidence interval 0.36 – 0.74, p < 0.001). Modeling found that under reasonable assumptions collider-stratification could account for sex-based differences in mortality. In this large registry of PAH patients new to a care center, men had worse survival than women despite having more favorable baseline characteristics. Collider-stratification bias could account for the observed greater mortality among men. [ABSTRACT FROM AUTHOR]

The Short Physical Performance Battery (SPPB) may be feasible for evaluating older adults undergoing myocardial revascularization surgery (MRS). However, it is necessary to verify its measurement properties and safety to use it for clinical practice. To investigate the reliability, hemodynamic responses, subjective perceived exertion (SPE), and adverse events during and after SPPB in older adults undergoing MRS. A cross-sectional and methodological study conducted with 85 older adults in the pre and postoperative periods of MRS. The hemodynamic responses [heart rate (HR) and systolic blood pressure (SBP)], SPE, and adverse events were evaluated before and after the SPPB. Two researchers performed the inter-rater reliability within a 30-minute interval, while the interval between measures for intra-rater reliability was 24 hours. The Friedman test was used to analyze hemodynamic and SPE responses. The intraclass correlation coefficient (ICC) and the coefficient variation of method error (CVME) were used for the reliability analysis. Increases in HR (p < 001), SBP (p < 0.01), and SPE (p < 0.01) were observed immediately after the SPPB. Only seven volunteers reported minor adverse events. Regarding reliability results, ICC(3,1) for intra-rater reliability varied from 0.66 to 0.87 and CVME from 4.80 to 8.82%. For inter-rater reliability, ICC(2,1) varied from 0.66 to 0.91 and CVME from 4.04 to 9.02%. The SPPB increased the HR, SBP, and SPE immediately after its execution. In addition, it showed light changes in SPE, few adverse events, and good reliability in older adults in the pre and postoperative MRS period. [ABSTRACT FROM AUTHOR]

Portopulmonary hypertension is an intractable form of pulmonary hypertension. Although liver transplantation is recommended for patients who respond poorly to treatments, the mechanisms by which liver transplantation improves pulmonary hypertension remain unclear. The present study investigated these mechanisms by retrospectively evaluating patients' data. This study retrospectively evaluated echocardiography and catheterization data before and after liver transplantation in 12 patients who underwent liver transplantation from 2001 to 2019. The 12 patients included one male and 11 females, of median age at liver transplantation of 10 years, 2 months. Nine patients underwent liver transplantation for congenital biliary atresia and three for portal vein aplasia or hypoplasia. Mean pulmonary arterial pressure was 44.1 ± 8.1 mmHg at the first cardiac catheter examination, 35.3 ± 7.8 mmHg before liver transplantation, and 29.5 ± 9.3 mmHg 6 months after liver transplantation. Pulmonary artery pressure was reduced by treatments of pulmonary hypertension and by liver transplantation. Pulmonary vascular resistance did not differ before and after liver transplantation, whereas the cardiac index decreased significantly, indicating that the significant reduction in mean pulmonary artery pressure was due to a decrease in cardiac index. Decreased cardiac index was thought to result from improvements in hyperdynamic conditions due to increased (normalized) systemic vascular resistance. Liver transplantation likely suppresses shear stress on pulmonary arteries, preventing further damage by hyper-circulation. A longer-term evaluation is required to determine the effect of improving pulmonary artery remodeling. [ABSTRACT FROM AUTHOR]

The progress in research on the physiology of the cardiovascular system made in the last 100 years allowed for the development of the pathogenesis not only of secondary forms of hypertension but also of primary hypertension. The main determinants of blood pressure are described by the relationship between stroke volume, heart rate, peripheral resistance, and arterial stiffness. The theories developed by Guyton and Folkow describe the importance of the volume factor and total peripheral resistance. However, none of them fully presents the pathogenesis of essential hypertension. The multifactorial model of primary hypertension pathogenesis developed by Irving Page in the 1940s, called Page's mosaic, covers most of the pathophysiological phenomena observed in essential hypertension. The most important pathophysiological phenomena included in Page's mosaic form a network of interconnected "nodes". New discoveries both from experimental and clinical studies made in recent decades have allowed the original Page mosaic to be modified and the addition of new pathophysiological nodes. Most of the clinical studies confirming the validity of the multifactorial pathogenesis of primary hypertension concern adults. However, hypertension develops in childhood and is even perinatally programmed. Therefore, the next nodes in Page's mosaic should be age and perinatal factors. This article presents data from pediatric clinical trials describing the most important pathophysiological processes associated with the development of essential hypertension in children and adolescents. [ABSTRACT FROM AUTHOR]

Emotion suppression may be linked to poor health outcomes through elevated stress-related physiology. The current meta-analyses investigate the magnitude of the association between suppression and physiological responses to active psychological stress tasks administered in the laboratory. Relevant articles were identified through Medline, PsychINFO, PubMed, and ProQuest. Studies were eligible if they (a) used a sample of healthy, human subjects; (b) assessed physiology during a resting baseline and active psychological stress task; and (c) measured self-report or experimentally manipulated suppression. Twenty-four studies were identified and grouped within two separate random effects meta-analyses based on study methodology, namely, manipulated suppression (k = 12) and/or self-report (k = 14). Experimentally manipulated suppression was associated with greater physiological stress reactivity compared to controls (Hg = 0.20, 95% CI [0.08, 0.33]), primarily driven by cardiac, hemodynamic, and neuroendocrine parameters. Self-report trait suppression was not associated with overall physiological stress reactivity but was associated with greater neuroendocrine reactivity (r = 0.08, 95% CI [0.01, 0.14]). Significant moderator variables were identified (i.e., type/duration of stress task, nature of control instructions, type of physiology, and gender). This review suggests that suppression may exacerbate stress-induced physiological arousal; however, this may differ based upon the chosen methodological assessment of suppression. [ABSTRACT FROM AUTHOR]

Purpose: Neck and upper-back stiffness is encountered in daily life, with symptoms appearing as dullness or aches predominantly in the trapezius muscle (TM). Our previous study demonstrated that TM hardness as measured with a muscle hardness meter correlates well with transverse cervical artery (TCA) flow supplying the TM. Muscle hardness meters, however, cannot measure hardness in the TM alone. Meanwhile, recent advances in ultrasound elastography have enabled the evaluation of localized hardness in targeted tissues. The present study, therefore, aimed to clarify the relationship between TM hardness as measured by elastography and TCA hemodynamics as measured on Doppler sonography, with reference to daily symptoms of upper-back stiffness. Methods: The study population comprised 66 healthy young adults (32 males, 34 females; mean age, 21 ± 1 years). Relationships were evaluated between TM hardness as a negative correlate of strain ratio from elastography and TCA hemodynamics on Doppler sonography. Hemodynamics in the TCA were evaluated according to the frequency of neck and upper-back stiffness. Results: TM strain ratio correlated with peak systolic velocity (PSV) in the TCA (r = 0.273, p = 0.036), particularly in symptomatic subjects (r = 0.417, p = 0.022). PSV in the TCA decreased with increasing frequency of daily symptoms (p = 0.045). Conclusion: TCA hemodynamics correlated with muscle hardness when evaluating localized TM hardness. This relationship and low PSV in the TCA were evident in symptomatic subjects. These results suggest that PSV in the TCA is associated with neck and upper-back stiffness. [ABSTRACT FROM AUTHOR]

Blood flow to the brain is a critical physiological function and is useful to monitor in critical care settings. Despite that, a surrogate is most likely measured instead of actual blood flow. Such surrogates include velocity measurements in the carotid artery and systemic blood pressure, even though true blood flow can actually be obtained using MRI and other modalities. Ultrasound is regularly used to measure blood flow and is, under certain conditions, able to provide quantitative volumetric blood flow in milliliters per minute. Unfortunately, most times the resulting flow data is not valid due to unmet assumptions (such as flow profile and angle correction). Color flow, acquired in three dimensions, has been shown to yield quantitative blood flow without any assumptions (3DVF). Here we are testing whether color flow can perform during physiological conditions common to severe injury. Specifically, we are simulating severe traumatic brain injury (epidural hematoma) as well as hemorrhagic shock with 50% blood loss. Blood flow was measured in the carotid artery of a cohort of 7 Yorkshire mix pigs (40–60 kg) using 3DVF (4D16L, LOGIQ 9, GE HealthCare, Milwaukee, WI, USA) and compared to an invasive flow meter (TS420, Transonic Systems Inc., Ithaca, NY, USA). Six distinct physiological conditions were achieved: baseline, hematoma, baseline 2, hemorrhagic shock, hemorrhagic shock plus hematoma, and post-hemorrhage resuscitation. Mean cerebral oxygen extraction ratio varied from 40.6% ± 13.0% of baseline to a peak of 68.4% ± 15.6% during hemorrhagic shock. On average 3DVF estimated blood flow with a bias of -9.6% (-14.3% root mean squared error) relative to the invasive flow meter. No significant flow estimation error was detected during phases of flow reversal, that was seen in the carotid artery during traumatic conditions. The invasive flow meter showed a median error of -11.5% to 39.7%. Results suggest that absolute volumetric carotid blood flow to the brain can be obtained and potentially become a more specific biomarker related to cerebral hemodynamics than current surrogate markers. [ABSTRACT FROM AUTHOR]

Background: Spinal anaesthesia decreases intra-operative pain, autonomic, somatic and endocrine responses. It also provides a quick onset and effective sensory & motor blockade. Methods: This study was conducted in the Department of Anaesthesiology, Rohilkhand medical college and hospital with the objective to compare Hyperbaric Bupivacaine, Levobupivacaine and Ropivacaine intrathecally for hemodynamic stability and post-operative analgesia in Infra umbilical surgeries. Results: Both hyperbaric levobupivacaine and hyperbaric ropivacaine have better hemodynamic stability in comparison to hyperbaric-bupivacaine, whereas hyperbaric-ropivacaine shows better result among all three groups. The mean onset time of sensory-blockade was shorter in hyperbaric bupivacaine group than hyperbaric-levobupivacaine group and delayed in hyperbaric-ropivacaine group. The peak height was more in hyperbaric bupivacaine group than hyperbariclevobupivacaine than hyperbaric ropivacaine group. The maximum duration of sensory-blockade was found more in hyperbaric bupivacaine group than hyperbaric-levobupivacaine Group and shortest in hyperbaric-ropivacaine group. Conclusion: Both hyperbaric-levobupivacaine and hyperbaric-ropivacaine have better hemodynamic stability, equally effective, lesser duration of sensory & motor-block in comparison to hyperbaric bupivacaine. [ABSTRACT FROM AUTHOR]

Introduction: Cardiovascular disease (CVD) accounts for a significant percentage of global deaths and emphasizes the importance of early detection for prevention. Endothelial dysfunction serves as a reversible precursor of atherosclerosis and plays a crucial role in the development of complications such as heart attacks and strokes. Assessment of endothelial function using flow-mediated dilation (FMD) in the brachial artery utilizing noninvasive ultrasound imaging provides promising opportunities for early detection and intervention strategies in cardiovascular health. Material and Method: The study employs meticulous data collection procedures through ultrasonographic scanning of the brachial artery to ensure precise measurements of parameters such as mean velocity, diameter, flow, shear stress, and percentage flow-mediated dilation. Result: Significantly, the study results revealed variations in blood sugar levels and % FMD between the control and case groups, highlighting potential differences in endothelial function and vascular health. Additionally, the study conducted a comparative analysis of data from different studies, providing valuable insights into the impact of shear stress on endothelial homeostasis and cardiovascular health. Conclusion: The comprehensive assessment of endothelial function and its correlation with cardiovascular disease risk, through advanced methodologies and meticulous data analysis, empowers researchers and healthcare practitioners with crucial insights into refining risk assessments and personalized treatment strategies in cardiovascular health. [ABSTRACT FROM AUTHOR]

Introduction: Trauma-induced hemorrhage is a leading cause of death in prehospital settings. Experimental data demonstrate that females have a lower tolerance to simulated hemorrhage (i.e., central hypovolemia). However, the mechanism(s) underpinning these responses are unknown. Therefore, this study aimed to compare autonomic cardiovascular responses during central hypovolemia between the sexes. We hypothesized that females would have a lower tolerance and smaller increase in muscle sympathetic nerve activity (MSNA) to simulated hemorrhage. Methods: Data from 17 females and 19 males, aged 19-45 yr, were retrospectively analyzed. Participants completed a progressive lower-body negative pressure (LBNP) protocol to presyncope to simulate hemorrhagic tolerance with continuous measures of MSNA and beat-to-beat hemodynamic variables. We compared responses at baseline, at two LBNP stages (-40 and -50 mmHg), and at immediately before presyncope. In addition, we compared responses at relative percentages (33%, 66%, and 100%) of hemorrhagic tolerance, calculated via the cumulative stress index (i.e., the sum of the product of time and pressure at each LBNP stage). Results: Females had lower tolerance to central hypovolemia (female: 561 ± 309 vs male: 894 ± 304 min⋅mmHg [time⋅LBNP]; P = 0.003). At LBNP -40 and -50 mmHg, females had lower diastolic blood pressures (main effect of sex: P = 0.010). For the relative LBNP analysis, females exhibited lower MSNA burst frequency (main effect of sex: P = 0.016) accompanied by a lower total vascular conductance (sex: P = 0.028; main effect of sex). Conclusions: Females have a lower tolerance to central hypovolemia, which was accompanied by lower diastolic blood pressure at -40 and -50 mmHg LBNP. Notably, females had attenuated MSNA responses when assessed as relative LBNP tolerance time. [ABSTRACT FROM AUTHOR]

Purpose: To examine hemodynamic and functional connectivity alterations and their association with neurocognitive and mental health indices in patients with chronic mild traumatic brain injury (mTBI). Methods: Resting-state functional MRI (rs-fMRI) and neuropsychological assessment of 37 patients with chronic mTBI were performed. Intrinsic connectivity contrast (ICC) and time-shift analysis (TSA) of the rs-fMRI data allowed the assessment of regional hemodynamic and functional connectivity disturbances and their coupling (or uncoupling). Thirty-nine healthy age- and gender-matched participants were also examined. Results: Patients with chronic mTBI displayed hypoconnectivity in bilateral hippocampi and parahippocampal gyri and increased connectivity in parietal areas (right angular gyrus and left superior parietal lobule (SPL)). Slower perfusion (hemodynamic lag) in the left anterior hippocampus was associated with higher self-reported symptoms of depression (r = − 0.53, p =.0006) and anxiety (r = − 0.484, p =.002), while faster perfusion (hemodynamic lead) in the left SPL was associated with lower semantic fluency (r = − 0.474, p =.002). Finally, functional coupling (high connectivity and hemodynamic lead) in the right anterior cingulate cortex (ACC)) was associated with lower performance on attention and visuomotor coordination (r = − 0.50, p =.001), while dysfunctional coupling (low connectivity and hemodynamic lag) in the left ventral posterior cingulate cortex (PCC) and right SPL was associated with lower scores on immediate passage memory (r = − 0.52, p =.001; r = − 0.53, p =.0006, respectively). Uncoupling in the right extrastriate visual cortex and posterior middle temporal gyrus was negatively associated with cognitive flexibility (r = − 0.50, p =.001). Conclusion: Hemodynamic and functional connectivity differences, indicating neurovascular (un)coupling, may be linked to mental health and neurocognitive indices in patients with chronic mTBI. [ABSTRACT FROM AUTHOR]

Purpose: To validate a semiautomated method for segmenting vein of Galen aneurysmal malformations (VGAM) and to assess the relationship between VGAM volume and other angioarchitectural features, cardiological findings, and outcomes. Methods: In this retrospective study, we selected all subjects with VGAM admitted to the Gaslini Children's Hospital between 2009 and 2022. Clinical data were retrieved from electronic charts. We compared 3D-Slicer segmented VGAM volumes obtained by two independent observers using phase-contrast MR venography to those obtained with manual measurements performed on T2-weighted images. The relationship between VGAM volumes and clinical and neuroimaging features was then explored. Results: Forty-three subjects with VGAM (22 males, mean age 6.56 days) were included in the study. Manual and semiautomated VGAM volumes were well correlated for both readers (r = 0.86 and 0.82, respectively). Regarding reproducibility, the inter-rater interclass correlation coefficients were 0.885 for the manual method and 0.992 for the semiautomated method (p < 0.001). The standard error for repeated measures was lower for the semiautomated method (0.04 versus 0.40 of manual method). Higher VGAM volume was associated with superior sagittal sinus narrowing, jugular bulb stenosis, and aqueductal stenosis (p < 0.05). A weak correlation was found between VGAM volume and straight sinus dilatation (r = 0.331) and superior sagittal sinus index (r = − 0.325). No significant associations were found with cardiac findings, post-embolization complications, and outcome (p > 0.05). Conclusions: Semiautomated VGAM volumetry is feasible and reliable with improved reproducibility compared to the manual method. VGAM volume is not a prognostic factor for clinical outcome, but it is related to other venous findings with potential hemodynamic effects. [ABSTRACT FROM AUTHOR]

We design a feasibility study to obtain a set of metabolic-hemodynamic habitats for tackling tumor spatial metabolic patterns with hemodynamic information. Preoperative data from 69 high-grade gliomas (HGG) patients with subsequent histologic confirmation of HGG were prospectively collected (January 2016 to March 2020) after concurrent chemoradiotherapy (CCRT). Four vascular habitats were automatically segmented by multiparametric magnetic resonance imaging (MRI). The metabolic information, either at enhancing or edema tumor regions, was obtained by two neuroradiologists. The relative habitat volumes were used for weight estimation procedures for computing the coefficients of a linear regression model using weighted least squares (WLS) for metabolite semiquantifications (i.e. the Cho/NAA ratio and the Cho/Cr ratio) at vascular habitats. Multivariate Cox proportional hazard regression analyses are used to obtain the odds ratio (OR) and develop a nomogram using weighted estimators corresponding to each covariate derived from Cox regression coefficients. There was a strongly correlation between perfusion indexes and the Cho/Cr ratio (rCBV, r =0.71) or Cho/NAA ratio (rCBV, r =0.66) at high-angiogenic enhancing tumor habitats (HAT) habitat. Compared isocitrate dehydrogenase (IDH) mutation to their wild type, the IDH wild type had significantly decreased Cho/Cr ratio (IDH mutation: Cho/Cr ratio = 2.44 ± 0.33, IDH wildtype: Cho/Cr ratio = 2.66 ± 0.36, p =0.02) and Cho/NAA ratio (IDH mutation: Cho/Cr ratio = 4.59 ± 0.61, IDH wildtype: Cho/Cr ratio = 4.99 ± 0.66, p =0.022) at the HAT. The C -index for the median progression-free survival (PFS) prediction was 0.769 for the Cho/NAA nomogram and 0.747 for the Cho/Cr nomogram through 1000 bootstrapping validation. Our findings suggest that spatial metabolism combined with hemodynamic heterogeneity is associated with individual PFS to HGG patients post-CCRT. • Metabolic habitat is a potential method to tackle tumor spatial metabolic pattern. • Metabolic habitat has achieved great evident AUC value for IDH mutation prediction. • Nomograms show that metabolic habitat is a potential tool to predict individual PFS. [ABSTRACT FROM AUTHOR]

In systemic sclerosis (SSc), pulmonary hypertension remains a significant cause of morbidity and mortality. Although conventionally classified as group 1 pulmonary arterial hypertension, systemic sclerosis-related pulmonary hypertension (SSc-PH) is a heterogeneous disease. The contribution of left-sided cardiac disease in SSc-PH remains poorly understood. How often does left ventricular (LV) dysfunction occur in SSc among patients undergoing right heart catheterization and how does coexistent LV dysfunction with SSc-PH affect all-cause mortality in this patient population? We conducted a retrospective, observational study of 165 patients with SSc who underwent both echocardiography and right heart catheterization. LV dysfunction was identified using LV global longitudinal strain (GLS) on speckle-tracking echocardiography based on a defined threshold of > −18%. SSc-PH was defined by a mean pulmonary artery pressure > 20 mmHg. Among patients with SSc who have undergone right heart catheterization, LV dysfunction occurred in 74.2% with SSc-PH and 51.2% without SSc-PH. The median survival of patients with SSc-PH and LV dysfunction was 67.9 (95% CI, 38.3-102.0) months, with a hazard ratio of 12.64 (95% CI, 1.73-92.60) for all-cause mortality when adjusted for age, sex, SSc disease duration, and FVC compared with patients with SSc without pulmonary hypertension with normal LV function. LV dysfunction is common in SSc-PH. Patients with SSc-PH and LV dysfunction by LV GLS have increased all-cause mortality. This suggests that LV GLS may be helpful in identifying underlying LV dysfunction and in risk assessment of patients with SSc-PH. [Display omitted] [ABSTRACT FROM AUTHOR]

Holstein cattle carrying a prolactin receptor gene mutation (SLICK) exhibit short and sleek hair coats (short-haired Holstein [SLK]) enhancing thermotolerance and productivity compared with wild type–haired Holstein (WT) under tropical conditions. The objectives were to unravel the physiological and molecular mechanisms that confer an advantage to this slick genotype in Puerto Rico and determine potential correlations between metabolites and physiological variables. At 160 ± 3 DIM we compared vaginal temperatures (VT) and voluntary solar radiation exposure (VSRE) during 48 h between 9 SLK and 9 WT Holsteins, whereas a subsample of 7 SLK and 7 WT were used to assess udder skin temperature, mammary gland hemodynamics and transcriptomics, and blood plasma untargeted metabolomics at a single time point. The SLK cattle showed lower VT throughout the day and greater VSRE at 1000 h and 1100 h compared with their WT counterparts. Total mammary blood flow (MBF) was greater in SLK Holsteins compared with WT. The metabolite 9-nitrooctadecenoic acid was identified as a potential biomarker for MBF; moreover, SLK cattle had greater amounts of this metabolite in their plasma. Prostaglandin D2 synthase (PTGS) was upregulated in the slick mammary gland, while plasma prostaglandin D2 was positively correlated with milk yield and increased in SLK Holsteins compared with WT. Interestingly, the arachidonic acid metabolism pathway was enriched in the mammary gland transcriptome and perturbed in the blood metabolome in the SLK Holsteins. In conclusion, SLK Holsteins exhibited lower body temperatures, greater VSRE, enhanced blood supply to the mammary gland, and alterations in genes and metabolites involved in arachidonic acid metabolism at the mammary gland and blood plasma. The usage of the SLK Holstein cattle genetics in dairy operations could be a feasible alternative to mitigate the adverse consequences of heat stress. [ABSTRACT FROM AUTHOR]

Malnourished patients with anorexia nervosa (AN) have lower plasma citrulline level compared to healthy controls. Citrulline is a non-essential amino-acid synthetized by the enterocyte and has functions affecting cardiovascular status. The aim of the study is to describe citrulline plasma level and to assess its relationship with hemodynamic status in a cohort of malnourished adult patients with AN. A retrospective observational study including malnourished patients with AN hospitalized between January 2018 and January 2019 for the treatment of severe malnutrition was carried out. Anthropometric measures, biochemical tests, and cardiac function indicators including doppler echocardiographic parameters were evaluated. Forty-eight patients with a median age of 29 [21–35.5] years old and body mass index (BMI) of 12 [10.5–-13.4] kg/m2 were included. Median systolic blood pressure (SBP) and median diastolic blood pressure (DBP) were respectively 99 [90–110] mmHg and 68 [59–73] mmHg. Median left ventricular ejection fraction (LVEF) was at 65 [58–69] %. Plasma citrulline level was under the normal range in 58% of patients and was positively correlated with fat mass, stroke volume, and left ventricular end diastolic volume, but not BMI. Citrulline level may be an innovative associated marker of hemodynamic status in malnourished patients with AN. Further research and prospective studies are needed to elucidate the specific pathways involved. [ABSTRACT FROM AUTHOR]

Background: Propofol is effective and used as a kind of routine anesthetics in procedure sedative anesthesia (PSA) for ureteroscopy. However, respiratory depression and unconscious physical activity always occur during propofol-based PSA, especially in elderly patients. Esketamine has sedative and analgesic effects but without risk of cardiorespiratory depression. The purpose of this study is to investigate whether esketamine can reduce the propofol median effective dose (ED50) for successful ureteroscope insertion in elderly male patients. Materials and methods: 49 elderly male patients undergoing elective rigid ureteroscopy were randomly divided into two groups: SK Group (0.25 mg/kg esketamine+propofol) and SF Group (0.1 µg/kg sufentanil+propofol). Patients in both two groups received propofol with initial bolus dose of 1.5 mg/kg after sufentanil or esketamine was administered intravenously. The effective dose of propofol was assessed by a modified Dixon's up-and-down method and then was adjusted with 0.1 mg/kg according to the previous patient response. Patients' response to ureteroscope insertion was classified as "movement" or "no movement". The primary outcome was the ED50 of propofol for successful ureteroscope insertion with esketamine or sufentanil. The secondary outcomes were the induction time, adverse events such as hemodynamic changes, hypoxemia and body movement were also measured. Result: 49 patients were enrolled and completed this study. The ED50 of propofol for successful ureteroscope insertion in SK Group was 1.356 ± 0.11 mg/kg, which was decreased compared with that in SF Group, 1.442 ± 0.08 mg/kg (P = 0.003). The induction time in SK Group was significantly shorter than in SF Group (P = 0.001). In SK Group, more stable hemodynamic variables were observed than in SF Group. The incidence of AEs between the two groups was not significantly different. Conclusion: The ED50 of propofol with esketamine administration for ureteroscope insertion in elderly male patients is 1.356 ± 0.11 mg/kg, significantly decreased in comparsion with sufentanil. Trial registration: Chinese Clinical Trial Registry, No: ChiCTR2300077170. Registered on 1 November 2023. Prospective registration. http://www.chictr.org.cn. [ABSTRACT FROM AUTHOR]

Hemodynamic parameters have been correlated with stroke, hypertension, and arterial stenosis. While only a few small studies have examined the link between hemodynamics and diabetes mellitus (DM). This case-control study enrolled 417 DM patients and 3475 non-DM controls from a community-based cohort. Peak systolic velocity (PSV), end-diastolic velocity (EDV), blood flow velocity (MFV), pulsatility index (PI), and the resistance index (RI) of the common carotid arteries were measured by color Doppler ultrasonography. Generalized linear regression analyses showed that as compared to the non-DM controls, the age-sex-adjusted means of PSV, EDV, and MFV were − 3.28 cm/sec, − 1.94 cm/sec, and − 2.38 cm/sec, respectively, lower and the age-sex-adjusted means of RI and PI were 0.013 and 0.0061, respectively, higher for the DM cases (all p-values < 0.0005). As compared to the lowest quartiles, the multivariable-adjusted ORs of DM for the highest quartiles of PSV, EDV, MFV, RI, and PI were 0.59 (95% confidence interval [CI] 0.41–0.83), 0.45 (95% CI 0.31–0.66), 0.53 (95% CI 0.37–0.77), 1.61 (95% CI 1.15–2.25), and 1.58 (95% CI 1.12–2.23), respectively. More importantly, the additions of EDV significantly improved the predictabilities of the regression models on DM. As compared to the model contained conventional CVD risk factors alone, the area under the receiver operating curve (AUROC) increased by 1.00% (95% CI 0.29–1.73%; p = 0.0059) and 0.80% (95% CI 0.15–1.46%; p = 0.017) for models that added EDV in continuous and quartile scales, respectively. Additionally, the additions of PSV and MFV also significantly improved the predictabilities of the regression models (all 0.01 < p-value < 0.05). This study reveals a significant correlation between DM and altered hemodynamic parameters. Understanding this relationship could help identify individuals at higher risk of DM and facilitate targeted preventive strategies to reduce cardiovascular complications in DM patients. [ABSTRACT FROM AUTHOR]

Sodium-glucose cotransporter-2 inhibitors (SGLT2is) have been shown to lower incident heart failure (HF) and HF hospitalizations, but the mechanisms of benefit in relation to invasive hemodynamics remain unclear. Using PRISMA guidelines, we systematically reviewed multiple online databases for randomized trials evaluating the effect of SGLT2i on invasive hemodynamics. Rest and peak exercise invasive hemodynamics were measured via right heart catheterization pre- and postintervention. Random effects model meta-analysis at a 95% confidence interval was done using RevMan 5.0. A total of 3 studies with a total of 145 patients were included in the meta-analysis. SGLT2i was significantly associated with a reduction in pulmonary capillary wedge pressure at rest and peak exercise. Similarly, SGLT2i reduced mean pulmonary artery pressure at rest and peak exercise, respectively; however, this was not statistically significant. This hypothesis-generating study offers mechanistic insights into the central hemodynamic effects of SGLT2i underpinning the HF benefits of SGLT2i. [ABSTRACT FROM AUTHOR]

Background: Pneumomediastinum and pneumorrachis are rare complications following epidural analgesia, that can either be asymptomatic or rarely can produce mild to moderate severity symptoms. Most reported cases regarding the presentation of these two entities with epidural analgesia concern asymptomatic patients, however there are cases reporting post-dural puncture headache and respiratory manifestations. Case presentation: We present a case where a combined lumbar epidural and spinal anesthesia was performed using the loss of resistance to air technique (LOR), on a 78-year-old Greek (Caucasian) male undergoing a total hip replacement. Despite being hemodynamically stable throughout the operation, two hours following epidural analgesia the patient manifested a sudden drop in blood pressure and heart rate that required the administration of adrenaline to counter. Pneumomediastinum, pneumorrachis and paravertebral soft tissue emphysema were demonstrated in a Computed Tomography scan. We believe that injected air from the epidural space and surrounding tissues slowly moved towards the mediastinum, stimulating the para-aortic ganglia causing parasympathetic stimulation and therefore hypotension and bradycardia. Conclusion: Anesthesiologists should be aware that epidural analgesia using the LOR to technique injecting air could produce a pneumomediastinum and pneumorrachis, which in turn could produce hemodynamic instability via parasympathetic stimulation. [ABSTRACT FROM AUTHOR]

Study objective: During cesarean section, hypotension is a frequent side effect of spinal anesthesia. As a sitting or lateral position is required for spinal anesthesia performance, which of these two positions is more likely to cause intraoperative nausea, vomiting, and hypotension is still unknown. This meta-analysis compared the effects of these two positions on maternal hemodynamics and intraoperative nausea and vomiting. Design: Systematic review and meta-analysis Setting: Operating room Patients: This study included 803 patients from 12 randomized controlled trials (RCTs). Interventions: Neuraxial anesthesia in sitting position vs. lateral position. Measurements: We chose RCTs comparing the effects of spinal anesthesia in the sitting and lateral positions on maternal hemodynamics by thoroughly searching PubMed, Embase, the Cochrane Library, and the Web of Science for articles published from database inception until October 31, 2022. The Cochrane Handbook was used to assess the methodological quality of each RCT; the results were analyzed using RevMan 5.4 software; and the Egger test was used to assess publication bias. Main results: 12 randomised controlled trials with 803 participants were ultimately included in the final analysis. No significant differences were observed between the two positions in terms of the incidence of hypotension(RR, 0.82; 95% CI, 0.58–1.16; P = 0.26; I2 = 66%), lowest systolic blood pressure(MD, -0.81; 95% CI, -7.38–5.75; P = 0.81; I2 = 86%), the dose of ephedrine(MD, -1.19; 95% CI, -4.91–2.52; P = 0.53; I2 = 83%), and number of parturients requiring ephedrine(RR, 0.97; 95% CI, 0.64–1.46; P = 0.88; I2 = 74%). For the incidence of intraoperative nausea and vomiting, there was no statistical difference between the two positions. Conclusion: Parturients undergoing elective cesarean section under spinal anesthesia in the sitting or lateral position experienced similar incidence of hypotension, and there were no significant differences between these two positions in terms of the amount of ephedrine administered or the number of patients needing ephedrine. In both positions, the frequency of nausea and vomiting was comparable. The ideal position for anesthesia can be chosen based on the preferences and individual circumstances of the parturient and anesthesiologist. [ABSTRACT FROM AUTHOR]

Participant movement is a major source of artifacts in functional near-infrared spectroscopy (fNIRS) experiments. Mitigating the impact of motion artifacts (MAs) is crucial to estimate brain activity robustly. Here, we suggest and evaluate a novel application of the nonlinear Hammerstein–Wiener model to estimate and mitigate MAs in fNIRS signals from direct-movement recordings through IMU sensors mounted on the participant's head (head-IMU) and the fNIRS probe (probe-IMU). To this end, we analyzed the hemodynamic responses of single-channel oxyhemoglobin (HbO) and deoxyhemoglobin (HbR) signals from 17 participants who performed a hand tapping task with different levels of concurrent head movement. Additionally, the tapping task was performed without head movements to estimate the ground-truth brain activation. We compared the performance of our novel approach with the probe-IMU and head-IMU to eight established methods (PCA, tPCA, spline, spline Savitzky–Golay, wavelet, CBSI, RLOESS, and WCBSI) on four quality metrics: SNR, △AUC, RMSE, and R. Our proposed nonlinear Hammerstein–Wiener method achieved the best SNR increase (p < 0.001) among all methods. Visual inspection revealed that our approach mitigated MA contaminations that other techniques could not remove effectively. MA correction quality was comparable with head- and probe-IMUs. [ABSTRACT FROM AUTHOR]

Simple Summary: Patent ductus arteriosus is a common congenital heart defect affecting various species, including dogs and humans. It can cause congestive heart failure and death if left-to-right shunting is substantial. In humans, assessment of the hemodynamic relevance of a patent ductus arteriosus includes evaluation of the post-ductal aortic flow pattern. We found that ultrasonographic assessment of abdominal aortic flow was feasible in dogs with a patent ductus arteriosus. However, in dogs with higher heart rates, assessment of end-diastolic flow was not always possible. A retrograde end-diastolic flow was the most accurate parameter for identifying dogs with a hemodynamically significant patent ductus arteriosus. In this multicenter, prospective, observational study, abdominal aortic flow was examined with pulsed-wave Doppler ultrasound in dogs with a left-to-right shunting patent ductus arteriosus (PDA) and in apparently healthy dogs. Forty-eight dogs with a PDA and 35 controls were included. In the dogs with a PDA, 37/48 had hemodynamically significant PDAs (hsPDAs) while 11/48 had non-hsPDAs, based on the presence or absence of echocardiographic signs of left-sided volume overload, respectively. In 12 dogs (4/35 control dogs, 7/37 dogs with an hsPDA and 1/11 dogs with a non-hsPDA), the diastole was too short to visualize the end-diastolic flow. Antegrade end-diastolic flow was observed in 30/35 controls and 6/11 dogs with a non-hsPDA. Absent end-diastolic flow was observed in 1/35 control dogs and 3/11 dogs with a non-hsPDA. Retrograde end-diastolic flow was observed in 30/37 dogs with an hsPDA and 1/11 dogs with a non-hsPDA. Twenty-one dogs (15 with an hsPDA and 6 with a non-hsPDA) were reassessed after PDA closure, and, in 19/21, end-diastolic flow was visualized: 17/19 showed an antegrade flow, 1/19 an absent flow and 1/19 a retrograde flow. Sensitivity and specificity of retrograde end-diastolic flow for detection of hsPDAs were 100% and 90%, respectively. In conclusion, ultrasonographic assessment of abdominal aortic flow was feasible in dogs with PDA. However, end-diastolic flow was not always visualized. The presence of a retrograde end-diastolic flow was an accurate finding for discriminating hsPDAs and non-hsPDAs. [ABSTRACT FROM AUTHOR]

Cupping therapy is a popular intervention for improving muscle recovery after exercise although clinical evidence is weak. Previous studies demonstrated that cupping therapy may improve microcirculation of the soft tissue to accelerate tissue healing. However, it is unclear whether the cupping size could affect the spatial hemodynamic response of the treated muscle. The objective of this study was to use 8-channel near-infrared spectroscopy to assess this clinical question by assessing the effect of 3 cupping sizes (35, 40, and 45 mm in inner diameter of the circular cup) under −300 mmHg for 5 min on the muscle hemodynamic response from the area inside and outside the cup, including oxyhemoglobin and deoxy-hemoglobin in 18 healthy adults. Two-way factorial design was used to assess the interaction between the cupping size (35, 40, and 45 mm) and the location (inside and outside the cup) and the main effects of the cupping size and the location. The two-way repeated measures ANOVA demonstrated an interaction between the cupping size and the location in deoxy-hemoglobin (P = 0.039) but no interaction in oxyhemoglobin (P = 0.100), and a main effect of the cup size (P = 0.001) and location (P = 0.023) factors in oxyhemoglobin. For the cupping size factor, the 45-mm cup resulted in a significant increase in oxyhemoglobin (5.738±0.760 μM) compared to the 40-mm (2.095±0.312 μM, P<0.001) and 35-mm (3.134±0.515 μM, P<0.01) cup. Our findings demonstrate that the cupping size and location factors affect the muscle hemodynamic response, and the use of multi-channel near-infrared spectroscopy may help understand benefits of cupping therapy on managing musculoskeletal impairment. [ABSTRACT FROM AUTHOR]

BACKGROUND: Heart failure triggers a shift in myocardial metabolic substrate utilization, favoring the ketone body 3-hydroxybutyrate as energy source. We hypothesized that 14-day treatment with ketone ester (KE) would improve resting and exercise hemodynamics and exercise capacity in patients with heart failure with reduced ejection fraction. METHODS: In a randomized, double-blind cross-over study, nondiabetic patients with heart failure with reduced ejection fraction received 14-day KE and 14-day isocaloric non-KE comparator regimens of 4 daily doses separated by a 14-day washout period. After each treatment period, participants underwent right heart catheterization, echocardiography, and blood sampling at plasma trough levels and after dosing. Participants underwent an exercise hemodynamic assessment after a second dosing. The primary end point was resting cardiac output (CO). Secondary end points included resting and exercise pulmonary capillary wedge pressure and peak exercise CO and metabolic equivalents. RESULTS: We included 24 patients with heart failure with reduced ejection fraction (17 men; 65±9 years of age; all White). Resting CO at trough levels was higher after KE compared with isocaloric comparator (5.2±1.1 L/min versus 5.0±1.1 L/min; difference, 0.3 L/min [95% CI, 0.1–0.5), and pulmonary capillary wedge pressure was lower (8±3 mm Hg versus 11±3 mm Hg; difference, −2 mm Hg [95% CI, −4 to −1]). These changes were amplified after KE dosing. Across all exercise intensities, KE treatment was associated with lower mean exercise pulmonary capillary wedge pressure (−3 mm Hg [95% CI, −5 to −1]) and higher mean CO (0.5 L/min [95% CI, 0.1–0.8]), significantly different at low to moderate steady-state exercise but not at peak. Metabolic equivalents remained similar between treatments. In exploratory analyses, KE treatment was associated with 18% lower NT-proBNP (N-terminal pro-B-type natriuretic peptide; difference, −98 ng/L [95% CI, −185 to −23]), higher left ventricular ejection fraction (37±5 versus 34±5%; P =0.01), and lower left atrial and ventricular volumes. CONCLUSIONS: KE treatment for 14 days was associated with higher CO at rest and lower filling pressures, cardiac volumes, and NT-proBNP levels compared with isocaloric comparator. These changes persisted during exercise and were achieved on top of optimal medical therapy. Sustained modulation of circulating ketone bodies is a potential treatment principle in patients with heart failure with reduced ejection fraction. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT05161650. [ABSTRACT FROM AUTHOR]

Objectives: To examine whether long-term air pollution exposure is associated with central hemodynamic and brachial artery stiffness parameters. Methods: We assessed central hemodynamic parameters including central blood pressure, cardiac parameters, systemic vascular compliance and resistance, and brachial artery stiffness measures [including brachial artery distensibility (BAD), compliance (BAC), and resistance (BAR)] using waveform analysis of the arterial pressure signals obtained from a standard cuff sphygmomanometer (DynaPulse2000A, San Diego, CA). The long-term exposures to particles with an aerodynamic diameter < 2.5 μm (PM2.5) and nitrogen dioxide (NO2) for the 3-year periods prior to enrollment were estimated at residential addresses using fine-scale intra-urban spatiotemporal models. Linear mixed models adjusted for potential confounders were used to examine associations between air pollution exposures and health outcomes. Results: The cross-sectional study included 2,387 Chicago residents (76% African Americans) enrolled in the ChicagO Multiethnic Prevention And Surveillance Study (COMPASS) during 2013–2018 with validated address information, PM2.5 or NO2, key covariates, and hemodynamics measurements. We observed long-term concentrations of PM2.5 and NO2 to be positively associated with central systolic, pulse pressure and BAR, and negatively associated with BAD, and BAC after adjusting for relevant covariates. A 1-µg/m3 increment in preceding 3-year exposures to PM2.5 was associated with 1.8 mmHg higher central systolic (95% CI: 0.98, 4.16), 1.0 mmHg higher central pulse pressure (95% CI: 0.42, 2.87), a 0.56%mmHg lower BAD (95% CI: -0.81, -0.30), and a 0.009 mL/mmHg lower BAC (95% CI: -0.01, -0.01). Conclusion: This population-based study provides evidence that long-term exposures to PM2.5 and NO2 is related to central BP and arterial stiffness parameters, especially among African Americans. [ABSTRACT FROM AUTHOR]

Rotary blood pumps (RBPs) operating at a constant speed generate non-physiologic blood pressure and flow rate, which can cause endothelial dysfunction, leading to adverse clinical events in peripheral blood vessels and other organs. Notably, pulsatile working modes of the RBP can increase vascular pulsatility to improve arterial endothelial function. However, the laws and related mechanisms of differentially regulating arterial endothelial function under different pulsatile working modes are still unclear. This knowledge gap hinders the optimal selection of the RBP working modes. To address these issues, this study developed a multi-element in vitro endothelial cell culture system (ECCS), which could realize in vitro cell culture effectively and accurately reproduce blood pressure, shear stress, and circumferential strain in the arterial endothelial microenvironment. Performance of this proposed ECCS was validated with numerical simulation and flow experiments. Subsequently, this study investigated the effects of four different pulsation frequency modes that change once every 1-4-fold cardiac cycles (80, 40, 80/3, and 20 cycles per min, respectively) of the RBP on the expression of nitric oxide (NO) and reactive oxygen species (ROS) in endothelial cells. Results indicated that the 2-fold and 3-fold cardiac cycles significantly increased the production of NO and prevented the excessive generation of ROS, potentially minimizing the occurrence of endothelial dysfunction and related adverse events during the RBP support, and were consistent with animal study findings. In general, this study may provide a scientific basis for the optimal selection of the RBP working modes and potential treatment options for heart failure. [ABSTRACT FROM AUTHOR]

Wall shear stress is an important parameter in hemodynamics. Normal wall shear stress maintains the physiological state of blood vessels, while abnormal wall shear stress is closely related to the pathological progression of atherosclerosis and aneurysm, which is one of the risk factors for the occurrence of malignant cardiovascular and cerebrovascular events. Abnormal wall shear stress destroys the normal function of endothelial cells through different pathogenesis, mediates the initiation and evolution of these two diseases. This article reviews the impact of wall shear stress on atherosclerosis and aneurysm based on literature research in recent years. [ABSTRACT FROM AUTHOR]

Objective: We aimed to investigate the effect of right ventricular energy failure (RVEF) on hemodynamic and clinical outcomes in patients diagnosed with chronic thromboembolic pulmonary hypertension (CTEPH) undergoing pulmonary endarterectomy (PEA) surgery or balloon pulmonary angioplasty (BPA). Patients and Methods: A total of 100 CTEPH patients planned for PEA or BPA were included in the study. Based on the presence of RVEF during diagnosis, patients divided into two groups. Hemodynamic data from right heart catheterization (RHC) were compared before and after procedures in 3-6 months follow up period. Results: Patients with RVEF revealed a decrease in mean pulmonary artery pressure (mPAP) from 54.67±12.27 mmHg to 36.12±11.76 mmHg (p:<0.001), mean right atrial pressure (mRAP) from 13.40±4.08 mmHg to 9.76±4.56 mmHg (p:0.003), and pulmonary vascular resistance (PVR) from 11.36±5.15 Wood Units (WU) to 5.46±3.30 WU (p <0.001). In the non-RVEF group, mPAP decreased from 38.82±12.61 mmHg to 30.81±10.57 mmHg (p:<0.001), mRAP from 7.09±3.02mmHg to 7.15±3.07mmHg (p: 0.917), and PVR from 6.33±3.65 WU to 4.09±2.31 WU (p:<0.001). Conclusion:The presence of RVEF at the time of diagnosis in CTEPH patients does not have a negative impact on early perioperative and 3-month postoperative outcomes following PEA or BPA. This high-risk patient group demonstrated significant hemodynamic and clinical benefits from both PEA and BPA. [ABSTRACT FROM AUTHOR]

Vascular remodeling is a physiological and pathological process in which abnormal changes in vascular cells and non-cellular components lead to the remodeling of inward and outward blood vessel wall or changes in lumen diameter. As the channels for blood flow, blood vessels are continuously affected by hemodynamic forces. When sensing the abnormal blood flow forces, the mechanically sensitive cell membrane structures such as G protein-coupled receptors, ion channels, cell surface glycocalyx, and integrins, as well as the extracellular matrix will induce the process of vascular endothelial dysfunction, endothelial-mesenchymal transition, smooth muscle cell phenotypic switching, pericyte morphological changes and extracellular matrix remodeling to participate in vascular remodeling. As shown by research, abnormal hemodynamics caused abnormal changes in vascular structure and function, which was the basic process for the occurrence and development of pan-vascular diseases such as atherosclerosis, hypertension, diabetes, non-alcoholic fatty liver disease, pulmonary hypertension and COVID-19. This paper reviewed the interaction and molecular mechanism between abnormal hemodynamics and vascular remodeling, and analyzed its influence on the pathogenesis of pan-vascular diseases, which could provide reference for formulating prevention and treatment strategies for pan-vascular diseases. [ABSTRACT FROM AUTHOR]

Introduction: Moyamoya disease (MMD) is a vascular disease with significant risk of mortality due to ischemia or hemorrhage in the brain. The goal of the study was to explore three-dimensional arterial spin labeling (3D-ASL) to improve evaluation of cerebral hemodynamics in patients with MMD. Methods: Our study included 54 cases of ischemic MMD and 42 cases of hemorrhagic MMD. Dynamic susceptibility contrast-enhanced perfusion-weighted imaging (DSC-PWI) and 3D-ASL were performed at 3.0 T. Based on these scans, cerebral blood flow (CBF), mean transit time (MTT), and time to peak (TTP) were calculated and compared between patients with different disease subtypes. Receiver operating characteristics analysis was used to assess the diagnostic sensitivity and specificity of different imaging procedures and parameters. Results: Our data suggested that CBF in the lesion area was more severely reduced in patients with hemorrhagic MMD than in those with ischemic MMD. The CBF parameter in 3D-ASL diagnosed hemorrhagic and ischemic MMD with a significant sensitivity and specificity of 80.59% and 57.41%, respectively, with an area under the curve (AUC) of 0.75. We also found that the relative CBF of 3D-ASL was more pronounced decreased and the relative MTT and TTP of DSC-PWI were significantly increased in patients with hemorrhagic MMD than those with ischemic MMD. Specificity and sensitivity and AUC of 3D-ASL were better than the comparison of absolute values from DSC-PWI scans. Conclusion: Our study indicated that 3D-ASL is powerful in differentiating patients with cerebral ischemic or hemorrhagic MMD, providing another diagnostic tool that could potentially improve precision medicine to monitoring MMD patients. [ABSTRACT FROM AUTHOR]

Background: Dexmedetomidine is a selective alpha-2-adrenoceptor agonist. It exerts both sedative and analgesic effects through mechanisms different from those of other sedatives. The safety and efficacy of dexmedetomidine are altered by various factors. Aims and Objectives: This study aims at identifying the various factors that will affect the sedative and hemodynamic responses of dexmedetomidine in seriously ill patients. Materials and Methods: A continuous infusion of dexmedetomidine (0.2-0.7 µg/kg/h) was administered to intensive care unit patients who needed sedation. We investigated the safety and effectiveness of administering dexmedetomidine between responders and non-responders over a short (=24 h) and lengthy (>24 h) period. Results: A total of 84 patients were analyzed who received dexmedetomidine. The longest possible duration of dexmedetomidine administration was 24.7 days and 7.8 days, respectively. Compared to the first 24 h, the number of patients who needed more sedatives or analgesics was not increasing beyond that time. In the first 24 h and after the first 24 h, 35 out of 84 patients (41.2%) and 22 out of 84 patients (26.3%), respectively, needed more sedatives; in the first 24 h and after the first 24 h, 22 out of 84 patients (26.0%) and 18 out of 84 patients (21.4%) needed more analgesics. Conclusion: The safety and effectiveness of dexmedetomidine were similar across the demographic factors in this study. The interindividual variability due to pharmacokinetic parameters can be further studied along with pharmacogenomic factors that may cause the difference in the responses to dexmedetomidine use. [ABSTRACT FROM AUTHOR]

Internal carotid artery (CA) stenosis is a primary etiological factor for stroke and transient ischemic attack. The severity of arterial stenosis significantly impacts patient health and treatment decisions. Therefore, we conducted computational fluid dynamics analyses on five carotid arteries (CAs) of severe stenosis and compared them with five CAs in the control group. We improved the three-element Windkessel model method by pre-calculating the constant-pressure outlet simulation of the first cardiac cycle, which accelerated the stability of the model. The research results show that vortices were observed at the bifurcation of the CAs in the control group, whereas in the severe stenosis group, vortices predominantly occurred within the carotid sinus downstream of the stenotic segment. Notably, the vortex flow in the carotid aneurysm downstream of the stenotic segment arises due to the cross-sectional constriction induced by stenosis, which always flows in a clockwise direction and may contribute to the formation of aneurysms distal to the stenotic region. A high time-averaged wall shear stress value can effectively identify the stenosis site of CAs, while a high relative residence time value marks the protrusion near the stenosis segment. This study delved into the hemodynamic parameters between the CAs of the severe stenosis group and the control group and provided robust clinical evidence for carotid atherosclerotic disease. [ABSTRACT FROM AUTHOR]

BACKGROUND: The incidence of arterial stenosis is increasing year by year. In order to better diagnose and treat arterial stenosis, numerical simulation technology has become a popular method. OBJECTIVE: A novel model is constructed to investigate the influence of microcirculation on the hemodynamics of artery bypass graft. METHODS: In this paper, a severely narrow artery bypass graft model is considered. The geometric shape includes a narrow artery tube and a bypass graft of the same diameter with a 45° suture angle. The fluid-structure interaction model is considered by finite element numerical calculation, and the flow is simulated with microcirculation as the outlet boundary condition. The changes of blood flow velocity, pressure and wall shear stress are analyzed. RESULTS: The results show that blood almost entirely flows into the graft tube and there is no recirculation area at the anastomosis. CONCLUSION: The artery bypass graft model considering microcirculation function could simulate the physiological characteristics of blood flow more reasonably, and it provide helps for clinicians to diagnose and treat arterial stenosis. [ABSTRACT FROM AUTHOR]

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is one of the most common chronic airway diseases in the world. OBJECTIVE: To predict the degree of mixed venous oxygen saturation (SvO2) impairment in patients with COPD by modeling using clinical-CT radiomics data and to provide reference for clinical decision-making. METHODS: A total of 236 patients with COPD diagnosed by CT and clinical data at Xiangyang No. 1 People's Hospital (n = 157) and Xiangyang Central Hospital (n = 79) from June 2018 to September 2021 were retrospectively analyzed. The patients were divided into group A (SvO ⩾ 2 62%, N = 107) and group B (SvO < 2 62%, N = 129). We set up training set and test set at a ratio of 7/3 and time cutoff spot; In training set, Logistic regression was conducted to analyze the differences in general data (e.g. height, weight, systolic blood pressure), laboratory indicators (e.g. arterial oxygen saturation and pulmonary artery systolic pressure), and CT radiomics (radscore generated using chest CT texture parameters from 3D slicer software and LASSO regression) between these two groups. Further the risk factors screened by the above method were used to establish models for predicting the degree of hypoxia in COPD, conduct verification in test set and create a nomogram. RESULTS: Univariate analysis demonstrated that age, smoking history, drinking history, systemic systolic pressure, digestive symptoms, right ventricular diameter (RV), mean systolic pulmonary artery pressure (sPAP), cardiac index (CI), pulmonary vascular resistance (PVR), 6-min walking distance (6MWD), WHO functional classification of pulmonary hypertension (WHOPHFC), the ratio of forced expiratory volume in the first second to the forced vital capacity (FEV1%), and radscore in group B were all significantly different from those in group A (P < 0.05). Multivariate regression demonstrated that age, smoking history, digestive symptoms, 6MWD, and radscore were independent risk factors for SvO2 impairment. The combined model established based on the abovementioned indicators exhibited a good prediction effect [AUC: 0.903; 95%CI (0.858–0.937)], higher than the general clinical model [AUC: 0.760; 95%CI (0.701–0.813), P < 0.05] and laboratory examination-radiomics model [AUC: 0.868; 95%CI (0.818–0.908), P = 0.012]. The newly created nomogram may be helpful for clinical decision-making and benefit COPD patients. CONCLUSION: SvO2 is an important indicator of hypoxia in COPD, and it is highly related to age, 6MWD, and radscore. The combined model is helpful for early identification of SvO2 impairment and adjustment of COPD treatment strategies. [ABSTRACT FROM AUTHOR]

OBJECTIVES The objective of this analysis was to assess the normal haemodynamic performance of contemporary surgical aortic valves at 1 year postimplant in patients undergoing surgical aortic valve replacement for significant valvular dysfunction. By pooling data from 4 multicentre studies, this study will contribute to a better understanding of the effectiveness of surgical aortic valve replacement procedures, aiding clinicians and researchers in making informed decisions regarding valve selection and patient management. METHODS Echocardiograms were assessed by a single core laboratory. Effective orifice area, dimensionless velocity index, mean aortic gradient, peak aortic velocity and stroke volume were evaluated. RESULTS The cohort included 2958 patients. Baseline age in the studies ranged from 70.1 ± 9.0 to 83.3 ± 6.4 years, and Society of Thoracic Surgeons risk of mortality was 1.9 ± 0.7 to 7.5 ± 3.4%. Twenty patients who had received a valve model implanted in fewer than 10 cases were excluded. Ten valve models (all tissue valves; n  = 2938 patients) were analysed. At 1 year, population mean effective orifice area ranged from 1.46 ± 0.34 to 2.12 ± 0.59 cm2, and dimensionless velocity index, from 0.39 ± 0.07 to 0.56 ± 0.15. The mean gradient ranged from 8.6 ± 3.4 to 16.1 ± 6.2 mmHg with peak aortic velocity of 1.96 ± 0.39 to 2.65 ± 0.47 m/s. Stroke volume was 75.3 ± 19.6 to 89.8 ± 24.3 ml. CONCLUSIONS This pooled cohort is the largest to date of contemporary surgical aortic valves with echocardiograms analysed by a single core lab. Overall haemodynamic performance at 1 year ranged from good to excellent. These data can serve as a benchmark for other studies and may be useful to evaluate the performance of bioprosthetic surgical valves over time. Clinical trial registration number NCT02088554, NCT02701283, NCT01586910 and NCT01531374. [ABSTRACT FROM AUTHOR]

The association between cerebral hemodynamics and cognitive impairment has been reported in neurodegenerative and cerebrovascular disorders (CVD). However, it is still unclear whether changes occur in the acute phase of CVD. Here we investigated cognitive and hemodynamic parameters and their association in patients with CVD during the acute and subacute phases. Seventy-three patients with mild stroke, not undergoing endovascular treatment, were recruited. All subjects were devoid of intracranial or external carotid stenosis, significant chronic cerebrovascular pathology, dementia or non-compensated cardiovascular diseases. Patients were evaluated within 7 days from symptoms onset (T1) and after 3 months (T2). Clinical and demographic data were collected. NIHSS, MoCA, FAB, and Word-Color Stroop test (WCST) were used to evaluate disease severity and cognitive functions. Basal hemodynamic parameters in the middle cerebral artery were measured with transcranial Doppler. Differences between T2 and T1, correlations between cognitive and hemodynamic variables at T1 and T2, as well as correlations between the T2-T1 variation in cognitive and hemodynamic parameters were assessed. At T1, cognitive performance of MoCA, FAB, and WCST was lower compared with T2; and pulsatility index, a parameter reflecting distal vascular resistance, was higher. However, no correlations between the changes in cognitive and hemodynamic variables were found; therefore, the two seems to be independent phenomena. In the acute phase, the linear association between cerebral blood flow and cognitive performances was lost, probably due to a differential effect of microenvironment changes and vascular-specific phenomena on cognition and cerebral hemodynamics. This relationship was partially restored in the subacute phase. [ABSTRACT FROM AUTHOR]

Dynamic cerebral autoregulation (dCA) is the mechanism that describes how the brain maintains cerebral blood flow approximately constant in response to short‐term changes in arterial blood pressure. This is known to be impaired in many different pathological conditions, including ischaemic and haemorrhagic stroke, dementia and traumatic brain injury. Many different approaches have thus been used both to analyse and to quantify this mechanism in a range of healthy and diseased subjects, including data‐driven models (in both the time and the frequency domain) and biophysical models. However, despite the substantial body of work on both biophysical models and data‐driven models of dCA, there remains little work that links the two together. One of the reasons for this is proposed to be the discrepancies between the time constants that govern dCA in models and in experimental data. In this study, the processes that govern dCA are examined and it is proposed that the application of biophysical models remains limited due to a lack of understanding about the physical processes that are being modelled, partly due to the specific model formulation that has been most widely used (the equivalent electrical circuit). Based on the analysis presented here, it is proposed that the two most important time constants are arterial transit time and feedback time constant. It is therefore time to revisit equivalent electrical circuit models of dCA and to develop a more physiologically realistic alternative, one that can more easily be related to experimental data. Key points: Dynamic cerebral autoregulation is governed by two time constants.The first time constant is the arterial transit time, rather than the traditional 'RC' time constant widely used in previous models.This arterial transit time is approximately 1 s in the brain.The second time constant is the feedback time constant, which is less accurately known, although it is somewhat larger than the arterial transit time.The equivalent electrical circuit model of dynamic cerebral autoregulation should be replaced with a more physiologically representative model. [ABSTRACT FROM AUTHOR]