Effects of acutely induced hypertension in cats on pial arteriolar caliber, local cerebral blood flow, and the blood-brain barrier

Quantification of dynamic cerebral autoregulation: welcome to the jungle!

PURPOSE

Patients with dysautonomia often experience symptoms such as dizziness, syncope, blurred vision and brain fog. Dynamic cerebral autoregulation, or the ability of the cerebrovasculature to react to transient changes in arterial blood pressure, could be associated with these symptoms.

METHODS

In this narrative review, we go beyond the classical view of cerebral autoregulation to discuss dynamic cerebral autoregulation, focusing on recent advances pitfalls and future directions.

RESULTS

Following some historical background, this narrative review provides a brief overview of the concept of cerebral autoregulation, with a focus on the quantification of dynamic cerebral autoregulation. We then discuss the main protocols and analytical approaches to assess dynamic cerebral autoregulation, including recent advances and important issues which need to be tackled.

CONCLUSION

The researcher or clinician new to this field needs an adequate comprehension of the toolbox they have to adequately assess, and interpret, the complex relationship between arterial blood pressure and cerebral blood flow in healthy individuals and clinical populations, including patients with autonomic disorders.

Can Post-Operative Posterior Reversible Encephalopathy Syndrome (PRES) Be Considered an Insidious Rare Surgical Complication?

Introduction: Posterior reversible encephalopathy syndrome (PRES) is a neurological disorder characterized by neurological symptoms and distinctive neuroimaging findings. There are a few cases reported in the literature in which PRES can occur after surgery, and there is no clear direct relationship between a procedure and its debut. Methods: We performed a review of the literature by analyzing all reported cases of PRES syndrome which debuted after a surgical procedure with the aim of identifying the clinical features, the timing of the symptoms' onset and the therapy of patients suffering from this unusual surgical complication. Results: The total number of patients collected was 47, with a mean age of 40.9 years. Postoperative PRES can occur in either pediatric or adult patients (ages 4-82 years). The most frequent form of comorbidity reported was cardiovascular disease (fourteen patients, 29.78%). Sixteen patients (36%) had no relevant risk factors or comorbidities at the time of the surgical procedure. The types of surgery most correlated were cranial neuro and maxillofacial surgery (twenty-one patients, 44.68%) followed by transplant surgery (eight patients, 17%). The time of onset of PRES after surgery occurred within the first 3 weeks (mean time of onset 4.7 days), and when rapidly treated with antihypertensive and antiepileptic drugs appeared to have a reversible and benign course. Conclusion: PRES syndrome can be considered a rare complication of procedures and can occur following a wide range of surgeries, especially cranial and transplant surgery. Being able to recognize it in time and treat it ensures a full reversibility of symptoms in most cases.

Posterior Reversible Encephalopathy Syndrome (PRES) in Systemic Lupus Erythematosus: A Rare Presentation

Posterior reversible encephalopathy syndrome (PRES) is a clinical condition that is characterized by intense headache and neurological deficits such as vision loss which are attributed to the vasogenic edema that occurs in the posterior cerebral cortex involving the occipital and parietal lobes. Although the classical demographies that are affected by the PRES are middle-aged postpartum females and those with renal dysfunction, rarely it is also seen in patients with collagen vascular disorders such as systemic lupus erythematosus (SLE). We report a case of PRES in a 32-year-old SLE patient.

Uremic encephalopathy: A definite diagnosis by magnetic resonance imaging?

The aim of this study was to investigate the magnetic resonance imaging (MRI) findings for the diagnose uremic encephalopathy and describe the usefulness of MRI findings in the ultimate diagnosis of uremic encephalopathy (UE). A total of 20 patients with uremic encephalopathy admitted to the hospital were evaluated in this prospective study. The clinical manifestations, laboratory and MRI imaging findings, demographic information, and clinical outcome were analyzed for each patient. We observed that the 20 prospectively reviewed patients with UE had no involvement of the basal ganglia or the lentiform fork sign (LFS). However, two-thirds of the patients had white matter involvement, and 80% of the subjects had cerebral or cortical atrophy. The arterial blood gas (ABG) analysis revealed that 50% of the patients suffered from metabolic acidosis (n=10). The results of the present study demonstrated that although the observation of Lentiform Fork Sign and Basal Ganglia involvement in MRI of UE patients is a specific finding the absence of which does not rule out UE. Thus, simultaneous examination of clinical manifestation and laboratory test analyses, along with imaging findings, should also be taken into account.

Alcohol consumption and MRI markers of brain structure and function: Cohort study of 25,378 UK Biobank participants

Moderate alcohol consumption is widespread but its impact on brain structure and function is contentious. The relationship between alcohol intake and structural and functional neuroimaging indices, the threshold intake for associations, and whether population subgroups are at higher risk of alcohol-related brain harm remain unclear. 25,378 UK Biobank participants (mean age 54.9 ± 7.4 years, 12,254 female) underwent multi-modal MRI 9.6 ± 1.1 years after study baseline. Alcohol use was self-reported at baseline (2006-10). T1-weighted, diffusion weighted and resting state images were examined. Lower total grey matter volumes were observed in those drinking as little as 7-14 units (56-112 g) weekly. Higher alcohol consumption was associated with multiple markers of white matter microstructure, including lower fractional anisotropy, higher mean and radial diffusivity in a spatially distributed pattern across the brain. Associations between functional connectivity and alcohol intake were observed in the default mode, central executive, attention, salience and visual resting state networks. Relationships between total grey matter and alcohol were stronger than other modifiable factors, including blood pressure and smoking, and robust to unobserved confounding. Frequent binging, higher blood pressure and BMI steepened the negative association between alcohol and total grey matter volume. In this large observational cohort study, alcohol consumption was associated with multiple structural and functional MRI markers in mid- to late-life.

Effect of sphenopalatine ganglion block on intracranial pressure and cerebral venous outflow oxygenation during craniotomy for supratentorial brain tumours

BACKGROUND

Intraoperative intracranial pressure (ICP) control continues to be a challenge for anaesthetists during craniotomies. Although many standard brain-dehydrating protocols are available, they may be ineffective in certain surgical situations and may result in harm either to the systemic or cerebral circulation. Sphenopalatine ganglion block (SPGB) can reverse the vasodilatory effects of anaesthesia during craniotomy.

METHODS

This prospective randomised study was carried from June 2020 to February 2021. Fifty-two patients were randomly allocated into two groups, the block group (B) and the non-block control group (Non). Twenty-six patients were enrolled in the (B) group and received a bilateral transnasal SPG block with 2% lidocaine using a hallow culture swab prior to anaesthesia induction. Intraoperative monitoring was performed using standard American Society of Anesthesiologists (ASA) monitors in addition to invasive monitoring using intra-arterial cannulas and jugular venous bulb catheters. Subdural ICP monitors were also employed. The arterio-jugular oxygen difference in mmol/l (AjvDO2) was then calculated. Mean flow velocity cm/s (MFV) and pulsatility index (PI) were monitored in both groups using Transcranial Doppler. Haemodynamic data were recorded every 30 min from induction of anaesthesia until the closure of the dura.

RESULTS

There was a significant difference in ICP prior to the dural opening between the block group (B), mean ± sd 7.58 ± 1.47, and the non-block group (Non), mean ± sd (11.69 ± 1.72), p-value < 0.001. There was no significant difference in MFV between (B) group, mean ± sd 72.65 ± 2.28 and (Non) group, mean ± sd 71.19 ± 3.09 before intubation (baseline values). While there was a significant difference after intubation between block group, mean ± sd 72.12 ± 1.77 and non - block group, mean ± sd 74.62 ± 5.07, p-value = 0.02. There was an insignificant difference between (B) and (Non) groups before intubation regarding PI values, while PI was significantly higher in (B) group than the (Non) group after intubation where mean ± sd was 1.17 ± 0.05 versus 0.96 ± 0.09, respectively, p-value = 0.001. There was no significant difference regarding cerebral oxygenation between the groups.

CONCLUSIONS

SPGB can control factors that increase CBF during anaesthesia by the block of parasympathetic vasodilatory fibres to the arterial system in the anterior cerebral circulation, while neither hindering cerebral venous drainage nor impairing cerebral oxygenation, as it gives no supply to cerebral veins and does not affect basal CBF. Additionally, it does not affect systemic circulation.

Cognitive Impairment in Acute Heart Failure: Narrative Review

Cognitive impairment (CI) represents a common but often veiled comorbidity in patients with acute heart failure (AHF) that deserves more clinical attention. In the AHF setting, it manifests as varying degrees of deficits in one or more cognitive domains across a wide spectrum ranging from mild CI to severe global neurocognitive disorder. On the basis of the significant negative implications of CI on quality of life and its overwhelming association with poor outcomes, there is a compelling need for establishment of detailed consensus guidelines on cognitive screening methods to be systematically implemented in the population of patients with heart failure (HF). Since limited attention has been drawn exclusively on the field of CI in AHF thus far, the present narrative review aims to shed further light on the topic. The underlying pathophysiological mechanisms of CI in AHF remain poorly understood and seem to be multifactorial. Different pathophysiological pathways may come into play, depending on the clinical phenotype of AHF. There is some evidence that cognitive decline closely follows the perturbations incurred across the long-term disease trajectory of HF, both along the time course of stable chronic HF as well as during episodes of HF exacerbation. CI in AHF remains a rather under recognized scientific field that poses many challenges, since there are still many unresolved issues regarding cognitive changes in patients hospitalized with AHF that need to be thoroughly addressed.

Losing the dogmatic view of cerebral autoregulation

In 1959, Niels Lassen illustrated the cerebral autoregulation curve in the classic review article entitled Cerebral Blood Flow and Oxygen Consumption in Man. This concept suggested a relatively broad mean arterial pressure range (~60-150 mmHg) wherein cerebral blood flow remains constant. However, the assumption that this wide cerebral autoregulation plateau could be applied on a within-individual basis is incorrect and greatly variable between individuals. Indeed, each data point on the autoregulatory curve originated from independent samples of participants and patients and represented interindividual relationships between cerebral blood flow and mean arterial pressure. Nonetheless, this influential concept remains commonly cited and illustrated in various high-impact publications and medical textbooks, and is frequently taught in medical and science education without appropriate nuances and caveats. Herein, we provide the rationale and additional experimental data supporting the notion we need to lose this dogmatic view of cerebral autoregulation.

CENTRAL NERVOUS SYSTEM RESPONSE TO CHRONIC KIDNEY DISEASE

Due to the aging of the human population, the prevalence of chronic diseases such as chronic kidney disease (CKD) is increasing every year. Chronic kidney disease is a general term that refers to heterogeneous disorders that affect kidney structure and function. Decrease in glomerular filtration can be defined as chronic and progressive deterioration in fluid-solute balance, metabolic and endocrine functions of the kidney. CKD often affects the elderly. With the advancement of age, some structural and functional changes occur in the kidneys. Therefore, the number of patients suffering from mild and moderate CKD is expected to increase in the future.CKD leads to the deep metabolic and hemodynamic changes that damage other organs, such as the heart and brain. CNS abnormalities and cognitive deficits progress with the severity of CBS and occurs mostly among hemodialysis patients. It also has great socio-economic effects on individuals. Since symptoms of CKD are not often found in patients, early recognition of risk factors is the main point. For this reason, it is necessary to identify possible protective and preventive treatments to be applied in at-risk groups and to examine these mechanisms for the treatment of the disease. This review provides available information on the relevant mechanisms.

Posterior reversible encephalopathy syndrome: A neuropsychiatric manifestation of systemic lupus erythematosus

Posterior Reversible Encephalopathy Syndrome (PRES) is an acute neurological syndrome clinically characterized by seizures, altered mental status, headache, and visual disturbances. It is caused by a variety of abnormalities in the endothelial function that ultimately result in vasogenic edema in the circulation of the central nervous system. This is reflected by the neuroimaging findings, that most often show reversible parieto-occipital edema. An important proportion of patients with PRES present with Systemic Lupus Erythematosus (SLE), and its complications, as their sole risk factors. This review describes the relationship between these two clinical entities and explains the pathophysiological models that have been proposed to describe the development of PRES. We explain how SLE can cause alterations in every pathway implicated in the development of PRES. Given the relatively high frequency and the distinct clinical course, PRES in the setting of SLE might be best described as a distinct neuropsychiatric syndrome associated with SLE.

Retrospective evaluation of labetalol as antihypertensive agent in dogs

Background

To evaluate the effect on arterial blood pressure (ABP) of labetalol infusion as treatment for perioperative non nociceptive acute hypertension in dogs. The clinical records of dogs receiving intra or postoperative labetalol infusion were retrospectively reviewed. Invasive systolic (SAP), mean (MAP) and diastolic (DAP) arterial pressure and heart rate (HR) before labetalol infusion (T0) and 15, 30, 45 and 60 min (T1, T2, T3 and T4 respectively) after infusion were retrieved. The dose rate of labetalol infusion and use of concurrently administered drugs that could have potentially affected ABP and/or HR were also recorded. ANOVA for repeated measures and Dunnett’s multiple comparison test were used to determine the effect of labetalol on ABP and HR. Differences were considered significant when p < 0.05.

Results

A total of 20 dogs met the inclusion criteria, and hypertension was documented after craniotomy (12/20), adrenalectomy (4/20) and other procedures (4/20). Five dogs received labetalol intraoperatively, 14 postoperatively, and 1 during the surgical procedure and recovery. Median infusion duration and rate were 463 (60-2120) minutes and 1.1 (0.2–3.4) mg/kg/h respectively. Median loading dose was 0.2 (0.2–0.4) mg/kg. Labetalol produced a significant decrease in SAP and DAP at all time points compared to T0 (p < 0.05), while the effect was not significant at T1 for MAP (p = 0.0519). Median maximum MAP decrease was 31 (20–90) mmHg. Heart rate did not increase significantly during treatment (p = 0.2454). Acepromazine given before or during labetalol treatment did not reduce significantly ABP (p = 0.735).

Conclusions

Labetalol produced a reliable and titratable decrease in ABP with non significant increase in HR.

[Posterior reversible encephalopathy syndrome and arterial hypertension]

OBJECTIVE

To identify a correlation between systolicdiastolic blood pressure (BP) and severity of clinical/radiological presentations in patients with posterior reversible encephalopathy syndrome (PRES).

MATERIAL AND METHODS

Clinical and paraclinic data of patients with PRES hospitalized in the Republican Clinical Hospital, Kazan in 2010-2018 were analyzed. Nineteen patients were found, all of them were women, aged 18-67 years, mean age 33.50±15.03 years. Clinical and paraclinic data included anamnesis, neurological examination, neuroimaging, first measurements of systolic and diastolic BP after symptoms'onset.

RESULTS AND CONCLUSION

Diastolic BP values can be associated with the incidence of depression of consciousness, systolic BP values - with the number of damaged structures. In total, BP is the significant factor implemented in the presence of endothelial dysfunction that defines the severity of encephalopathy.

Posterior Reversible Encephalopathy Syndrome (PRES): Pathophysiology and Neuro-Imaging

Posterior reversible encephalopathy syndrome (PRES) represents a unique clinical entity with non-specific clinical symptoms and unique neuroradiological findings. This syndrome may present with a broad range of clinical symptoms from headache and visual disturbances to seizure and altered mentation. Typical imaging findings include posterior-circulation predominant vasogenic edema. Although there are many well-documented diseases associated with PRES, the exact pathophysiologic mechanism has yet to be fully elucidated. Generally accepted theories revolve around disruption of the blood-brain barrier secondary to elevated intracranial pressures or endothelial injury. In this article, we will review the clinical, typical, and atypical radiological features of PRES, as well as the most common theories behind the pathophysiology of PRES. Additionally, we will discuss some of the treatment strategies for PRES related to the underlying disease state.

Cerebellar Parieto-occipital Posterior Reversible Encephalopathy Syndrome and Cerebral Metamorphopsia Associated with Asymptomatic Atrial Septum Vegetation and Renal Disease: Case Report

Patient: Female, 25-year-old

Final Diagnosis: Posterior reversible encephalopathy syndrome

Symptoms: Visual disturbances

Medication: —

Clinical Procedure: —

Specialty: Neurology

Plasticity of cardiovascular chemoreflexes after prolonged unilateral carotid body denervation: implications for its therapeutic use

Unilateral carotid body denervation has been proposed as treatment for sympathetic-related human diseases such as systolic heart failure, hypertension, obstructive sleep apnea, and cardiometabolic diseases. The long-term therapeutic effects of carotid body removal will be maintained if the remnant "buffer nerves," that is, the contralateral carotid nerve and the aortic nerves that innervate second-order neurons at the solitary tract nuclei (NTS), do not modify their contributions to the cardiovascular chemoreflexes. Here, we studied the cardiovascular chemoreflexes 1 mo after unilateral carotid body denervation either by excision of the petrosal ganglion (petrosal ganglionectomy, which eliminates central carotid afferents) or exeresis of a segment of one carotid nerve (carotid neurectomy, which preserves central afferents). Cardiovascular chemoreflexes were induced by intravenous (iv) injections of sodium cyanide in pentobarbitone-anesthetized adult cats. After 1 mo of unilateral petrosal ganglionectomy, without significant changes in basal arterial pressure, the contribution of the contralateral carotid nerve to the chemoreflex increases in arterial pressure was enhanced without changes in the contribution provided by the aortic nerves. By contrast, after 1 mo of unilateral carotid neurectomy, the contribution of remnant buffer nerves to cardiovascular chemoreflexes remained unmodified. These results indicate that a carotid nerve interruption involving denervation of second-order chemosensory neurons at the NTS will trigger cardiovascular chemoreflex plasticity on the contralateral carotid pathway. Then, unilateral carotid body denervation as therapeutic tool should consider the maintenance of the integrity of carotid central chemoafferents to prevent plasticity on remnant buffer nerves.NEW & NOTEWORTHY Unilateral carotid body denervation has been proposed as treatment for sympathetic hyperactivity-related human disorders. Its therapeutic effectiveness for maintaining a persistent decrease in the sympathetic outflow activity will depend on the absence of compensatory chemoreflex plasticity in the remnant carotid and aortic afferents. Here, we suggest that the integrity of central afferents after carotid body denervation is essential to prevent the emergence of plastic functional changes on the contralateral "intact" carotid nerve.

Advanced Imaging Techniques in Diagnosis of Posterior Reversible Encephalopathy Syndrome (PRES)

Diagnosis of Posterior Reversible Encephalopathy Syndrome (PRES) in some circumstances can be challenging and structural imaging may not be sufficient to distinguish it from other differential diagnostic considerations. Advanced imaging techniques, such as MR spectroscopy or positron emission tomography (PET) can provide additional information to determine the diagnosis. Other techniques, such as susceptibility weighted imaging (SWI) improves detection of hemorrhage which has prognostic role. CT or MR Perfusion as well as Single-Photon Emission Computed Tomography (SPECT) are more useful to understand the underlying vasculopathic changes in PRES and may answer some of the unresolved controversies in pathophysiology of this complex disease. In this review we summarized the findings of previous studies using these advanced methods and their utilities in diagnosis or prognosis of PRES.

Imaging of Atypical and Complicated Posterior Reversible Encephalopathy Syndrome

Posterior reversible encephalopathy syndrome (PRES) is a condition clinically characterized by headache, altered mental status, seizures, and visual loss and may be associated with systemic hypertension, preeclampsia/eclampsia, chemotherapy, immunosuppressive therapies in the setting of organ transplantation, and uremic encephalopathy. While brain imaging in patients with PRES typically reveals symmetric vasogenic edema within the parietal and occipital lobes, PRES may present with atypical imaging findings such as central brainstem and deep gray involvement without subcortical edema, and even spinal cord involvement. Additionally, PRES may be complicated in some cases by the presence of cytotoxic edema and hemorrhage. This review will serve to summarize the pathophysiologic theories and controversies underlying PRES, imaging features encountered in atypical and complicated PRES, and the implications these findings may have on patient prognosis.

Exposure to Blast Overpressure Impairs Cerebral Microvascular Responses and Alters Vascular and Astrocytic Structure

Exposure to blast overpressure may result in cerebrovascular impairment, including cerebral vasospasm. The mechanisms contributing to this vascular response are unclear. The aim of this study was to evaluate the relationship between blast and functional alterations of the cerebral microcirculation and to investigate potential underlying changes in vascular microstructure. Cerebrovascular responses were assessed in sham- and blast-exposed male rats at multiple time points from 2 h through 28 days after a single 130-kPa (18.9-psi) exposure. Pial microcirculation was assessed through a cranial window created in the parietal bone of anesthetized rats. Pial arteriolar reactivity was evaluated in vivo using hypercapnia, barium chloride, and serotonin. We found that exposure to blast leads to impairment of arteriolar reactivity >24 h after blast exposure, suggesting delayed injury mechanisms that are not simply attributed to direct mechanical deformation. Observed vascular impairment included a reduction in hypercapnia-induced vasodilation, increase in barium-induced constriction, and reversal of the serotonin effect from constriction to dilation. A reduction in vascular smooth muscle contractile proteins consistent with vascular wall proliferation was observed, as well as delayed reduction in nitric oxide synthase and increase in endothelin-1 B receptors, mainly in astrocytes. Collectively, the data show that exposure to blast results in delayed and prolonged alterations in cerebrovascular reactivity that are associated with changes in the microarchitecture of the vessel wall and astrocytes. These changes may contribute to long-term pathologies involving dysfunction of the neurovascular unit, including cerebral vasospasm.

Pathophysiology of Lacunar Stroke: History's Mysteries and Modern Interpretations

Since the term "lacune" was adopted in the 1800s to describe infarctions from cerebral small vessels, their underlying pathophysiological basis remained obscure until the 1960s when Charles Miller Fisher performed several autopsy studies of stroke patients. He observed that the vessels displayed segmental arteriolar disorganization that was associated with vessel enlargement, hemorrhage, and fibrinoid deposition. He coined the term "lipohyalinosis" to describe the microvascular mechanism that engenders small subcortical infarcts in the absence of a compelling embolic source. Since Fisher's early descriptions of lipohyalinosis and lacunar stroke (LS), there have been many advancements in the understanding of this disease process. Herein, we review lipohyalinosis as it relates to modern concepts of cerebral small vessel disease (cSVD). We discuss clinical classifications of LS as well as radiographic definitions based on modern neuroimaging techniques. We provide a broad and comprehensive overview of LS pathophysiology both at the vessel and parenchymal levels. We also comment on the role of biomarkers, the possibility of systemic disease processes, and advancements in the genetics of cSVD. Lastly, we assess preclinical models that can aid in studying LS disease pathogenesis. Enhanced understanding of this highly prevalent disease will allow for the identification of novel therapeutic targets capable of mitigating disease sequelae.

The Ca2+-Binding S100B Protein: An Important Diagnostic and Prognostic Neurobiomarker in Pediatric Laboratory Medicine

In recent decades a significant scientific effort has focused on projects regarding the use of neurobiomarkers in perinatal medicine with a view to understanding the mechanisms that interfere with physiological patterns of brain development and lead to ominous effects in several human diseases. Numerous potential neurobiomarkers have been proposed for use in monitoring high-risk fetuses and newborns, including markers of oxidative stress, neuroproteins, and vasoactive agents. Nonetheless, the use of these markers in clinical practice remains a matter of debate. Recently, the calcium-binding S100B protein has been proposed as being an ideal neurobiomarker, thanks to its simple availability and easy reproducibility, to the possibility of detecting it noninvasively in biological fluids with good reproducibility, and to the possibility of a longitudinal evaluation in relation to reference curves. The present chapter contains an overview of the most significant studies on the assessment of S100B in different biological fluids as a trophic factor and/or marker of brain damage in high-risk fetuses and newborns.

The importance of comorbidities in ischemic stroke: Impact of hypertension on the cerebral circulation

Comorbidities are a hallmark of stroke that both increase the incidence of stroke and worsen outcome. Hypertension is prevalent in the stroke population and the most important modifiable risk factor for stroke. Hypertensive disorders promote stroke through increased shear stress, endothelial dysfunction, and large artery stiffness that transmits pulsatile flow to the cerebral microcirculation. Hypertension also promotes cerebral small vessel disease through several mechanisms, including hypoperfusion, diminished autoregulatory capacity and localized increase in blood-brain barrier permeability. Preeclampsia, a hypertensive disorder of pregnancy, also increases the risk of stroke 4-5-fold compared to normal pregnancy that predisposes women to early-onset cognitive impairment. In this review, we highlight how comorbidities and concomitant disorders are not only risk factors for ischemic stroke, but alter the response to acute ischemia. We focus on hypertension as a comorbidity and its effects on the cerebral circulation that alters the pathophysiology of ischemic stroke and should be considered in guiding future therapeutic strategies.

Optical imaging and modulation of neurovascular responses

The cerebral microvasculature consists of pial vascular networks, parenchymal descending arterioles, ascending venules and parenchymal capillaries. This vascular compartmentalization is vital to precisely deliver blood to balance continuously varying neural demands in multiple brain regions. Optical imaging techniques have facilitated the investigation of dynamic spatial and temporal properties of microvascular functions in real time. Their combination with transgenic animal models encoding specific genetic targets have further strengthened the importance of optical methods for neurovascular research by allowing for the modulation and monitoring of neuro vascular function. Image analysis methods with three-dimensional reconstruction are also helping to understand the complexity of microscopic observations. Here, we review the compartmentalized cerebral microvascular responses to global perturbations as well as regional changes in response to neural activity to highlight the differences in vascular action sites. In addition, microvascular responses elicited by optical modulation of different cell-type targets are summarized with emphasis on variable spatiotemporal dynamics of microvascular responses. Finally, long-term changes in microvascular compartmentalization are discussed to help understand potential relationships between CBF disturbances and the development of neurodegenerative diseases and cognitive decline.

The Hippocampal Neuro-Glio-Vascular Network: Metabolic Vulnerability and Potential Neurogenic Regeneration in Disease

Brain metabolism is a fragile balance between nutrient/oxygen supply provided by the blood and neuronal/glial demand. Small perturbations in these parameters are necessary for proper homeostatic functioning and information processing, but can also cause significant damage and cell death if dysregulated. During embryonic and early post-natal development, massive neurogenesis occurs, a process that continues at a limited rate in adulthood in two neurogenic niches, one in the lateral ventricle and the other in the hippocampal dentate gyrus. When metabolic demand does not correspond with supply, which can occur dramatically in the case of hypoxia or ischemia, or more subtly in the case of neuropsychiatric or neurodegenerative disorders, both of these neurogenic niches can respond—either in a beneficial manner, to regenerate damaged or lost tissue, or in a detrimental fashion—creating aberrant synaptic connections. In this review, we focus on the complex relationship that exists between the cerebral vasculature and neurogenesis across development and in disease states including hypoxic-ischemic injury, hypertension, diabetes mellitus, and Alzheimer’s disease. Although there is still much to be elucidated, we are beginning to appreciate how neurogenesis may help or harm the metabolically-injured brain, in the hopes that these insights can be used to tailor novel therapeutics to regenerate damaged tissue after injury.

Controversy of posterior reversible encephalopathy syndrome: what have we learnt in the last 20 years?

Over two decades have passed since posterior reversible encephalopathy syndrome (PRES) was first described in 1996. It has becoming increasingly recognised because of improved and more readily available imaging modality. The exact pathophysiological mechanism is not completely understood and remains controversial at present. Precise diagnosis is essential to guide prompt, proper management. Our ability of differentiating it from other acute neurological disorders is likely to improve as we learnt more about the spectrum of this entity in the last 20 years. We emphasise the importance of recognising its diagnostic criteria and biomarker, which would be of great relevance to either outcome evaluation or study design. PRES has a favourable prognosis generally, but neurological sequelae and even fatalities can occur, especially in severe forms that might cause substantial morbidity and even mortality, particularly when the syndrome is complicated by intracranial haemorrhage or brain infarction. In this review, the pathophysiology, approach to diagnosis, some controversies as to the prognosis, as well as the future research direction of PRES are described.

Increased blood pressure variability upon standing up improves reproducibility of cerebral autoregulation indices

Dynamic cerebral autoregulation, that is the transient response of cerebral blood flow to changes in arterial blood pressure, is currently assessed using a variety of different time series methods and data collection protocols. In the continuing absence of a gold standard for the study of cerebral autoregulation it is unclear to what extent does the assessment depend on the choice of a computational method and protocol. We use continuous measurements of blood pressure and cerebral blood flow velocity in the middle cerebral artery from the cohorts of 18 normotensive subjects performing sit-to-stand manoeuvre. We estimate cerebral autoregulation using a wide variety of black-box approaches (including the following six autoregulation indices ARI, Mx, Sx, Dx, FIR and ARX) and compare them in the context of reproducibility and variability. For all autoregulation indices, considered here, the intra-class correlation was greater during the standing protocol, however, it was significantly greater (Fisher's Z-test) for Mx (p < 0.03), Sx (p < 0.003) and Dx (p < 0.03). In the specific case of the sit-to-stand manoeuvre, measurements taken immediately after standing up greatly improve the reproducibility of the autoregulation coefficients. This is generally coupled with an increase of the within-group spread of the estimates.

Cerebral hemodynamic and metabolic changes in fulminant hepatic failure

ABSTRACT Intracranial hypertension and brain swelling are a major cause of morbidity and mortality of patients suffering from fulminant hepatic failure (FHF). The pathogenesis of these complications has been investigated in man, in experimental models and in isolated cell systems. Currently, the mechanism underlying cerebral edema and intracranial hypertension in the presence of FHF is multi-factorial in etiology and only partially understood. The aim of this paper is to review the pathophysiology of cerebral hemodynamic and metabolism changes in FHF in order to improve understanding of intracranial dynamics complication in FHF.

Various Imaging Manifestations of Posterior Reversible Encephalopathy Syndrome (PRES) on Magnetic Resonance Imaging (MRI)

Background

Posterior reversible encephalopathy syndrome (PRES), also called the acute hypertensive encephalopathy and reversible posterior leukoencephalopathy syndrome (RPLS), is a neurotoxic syndrome of cerebral vasoregulation classically characterized by bilaterally symmetrical parieto-occipital edema. However, the imaging findings are variable and may occur in other locations such as the frontal lobes, thalami, basal ganglia and brainstem. Most commonly, PRES presents with hyperintense signals on T2 and FLAIR sequences. Restricted diffusion and hemorrhage are rare. This study presents the typical and atypical manifestations of PRES on 3T MR images.

Material/Methods

It is a retrospective study analyzing a radiology report database and MR images of 92 patients with a clinical and radiological diagnosis of PRES. The brain MRI images of these patients were evaluated. The regions involved and the signal intensity of the affected areas on T1, T2, FLAIR and DW sequences were recorded. The location of the abnormal signal intensity as well as the presence or absence of atypical features such as diffusion restriction and hemorrhage were also recorded.

Results

The most commonly affected region was the parieto-occipital lobes (100%), however, other atypical regions involved were the frontal lobes (30.4%), temporal lobes (8.69%), basal ganglia (22%), cerebellum(17.39%), brainstem(9%) and thalamus(4%). Some of the cases showed restricted diffusion (43%) and hemorrhage (9%).

Conclusions

The involvement of the parieto-occipital, frontal and temporal lobes is common in PRES. Occasionally, there may be an involvement of the basal ganglia, cerebellum and brainstem, with or without hemorrhage and restricted diffusion. Radiologists should be aware of the typical and atypical imaging manifestations of PRES in order to make an accurate diagnosis.

Neurological Complications of Renal Disease

Neurological manifestations related to electrolyte disorders, drug toxicity, and uremia are common in chronic kidney disease (CKD). Seizures and coma are frequent complications of acute renal insufficiency (uremia), whereas peripheral neuropathy and encephalopathy, observed in progressive uremia, are terminal events. Failure to excrete metabolic products causes their accumulation and can lead to severe intoxication. Clinically, the signs and symptoms of uremia can vary widely, depending on the biological characteristics of the patient, the specific type of renal disease, and the time of the uremic intoxication. CKD is an increasing problem worldwide and is now being recognized as a global health burden particularly for cardiovascular and cerebrovascular ischemic events. Despite improvements in the medical management of advanced CKD, including dialysis and transplantation, patients manifest a number of symptoms that neurologists are often confronted with. Appropriate drug dosing, awareness of potential side effects of medications, prompt diagnosis, and treatment are essential in preventing neurological long-term morbidity and mortality.

Posterior reversible encephalopathy syndrome

The posterior reversible encephalopathy syndrome (PRES) is a neurological disorder of (sub)acute onset characterized by varied neurological symptoms, which may include headache, impaired visual acuity or visual field deficits, disorders of consciousness, confusion, seizures, and focal neurological deficits. In a majority of patients the clinical presentation includes elevated arterial blood pressure up to hypertensive emergencies. Neuroimaging, in particular magnetic resonance imaging, frequently shows a distinctive parieto-occipital pattern with a symmetric distribution of changes reflecting vasogenic edema. PRES frequently develops in the context of cytotoxic medication, (pre)eclampsia, sepsis, renal disease or autoimmune disorders. The treatment is symptomatic and is determined by the underlying condition. The overall prognosis is favorable, since clinical symptoms as well as imaging lesions are reversible in most patients. However, neurological sequelae including long-term epilepsy may persist in individual cases.

Posterior reversible encephalopathy in the intensive care unit

Posterior reversible encephalopathy syndrome (PRES) is increasingly diagnosed in the emergency department, and medical and surgical intensive care units. PRES is characterized by acute onset of neurologic symptoms in the setting of blood pressure fluctuations, eclampsia, autoimmune disease, transplantation, renal failure, or exposure to immunosuppressive or cytotoxic drugs, triggers known to admit patients to the intensive care unit (ICU). Although the exact pathophysiology remains unknown, there is growing consensus that PRES results from endothelial dysfunction. Because of the heterogeneous nature of the disorder, it is probable that different mechanisms of endothelial injury are etiologically important in different clinical situations. The presence of bilateral vasogenic edema on brain imaging, particularly in parieto-occipital regions, is of great diagnostic utility but PRES remains a clinical diagnosis. Although largely reversible, PRES can result in irreversible neurologic injury and even death. The range of clinical and radiographic manifestations of the syndrome is probably broader than previously thought, and it is imperative that clinicians become familiar with the full spectrum of the disorder, as prompt recognition and elimination of an inciting factor improve outcome. PRES may be the most frequent toxic-metabolic encephalopathy seen in the ICU.

Multimodal brain monitoring in fulminant hepatic failure

Acute liver failure, also known as fulminant hepatic failure (FHF), embraces a spectrum of clinical entities characterized by acute liver injury, severe hepatocellular dysfunction, and hepatic encephalopathy. Cerebral edema and intracranial hypertension are common causes of mortality in patients with FHF. The management of patients who present acute liver failure starts with determining the cause and an initial evaluation of prognosis. Regardless of whether or not patients are listed for liver transplantation, they should still be monitored for recovery, death, or transplantation. In the past, neuromonitoring was restricted to serial clinical neurologic examination and, in some cases, intracranial pressure monitoring. Over the years, this monitoring has proven insufficient, as brain abnormalities were detected at late and irreversible stages. The need for real-time monitoring of brain functions to favor prompt treatment and avert irreversible brain injuries led to the concepts of multimodal monitoring and neurophysiological decision support. New monitoring techniques, such as brain tissue oxygen tension, continuous electroencephalogram, transcranial Doppler, and cerebral microdialysis, have been developed. These techniques enable early diagnosis of brain hemodynamic, electrical, and biochemical changes, allow brain anatomical and physiological monitoring-guided therapy, and have improved patient survival rates. The purpose of this review is to discuss the multimodality methods available for monitoring patients with FHF in the neurocritical care setting.

Hypertensive Encephalopathy in Cats with Reduced Renal Function

The clinical, hemodynamic, and pathologic features of hypertensive encephalopathy in two cats with reduced renal mass are described. The cats developed a progressive syndrome of lethargy, ataxia, blindness, stupor, and seizures following an abrupt increase in blood pressure associated with a surgical reduction in renal mass. The cats had severe gross brain edema, evidenced by cerebellar changes of caudal coning and cranial displacement over the corpora quadrigemina and cerebral changes of widening and flattening of the gyri. Histologically, interstitial edema was most pronounced in the cerebral white matter. Hypertensive vascular lesions were present as hyaline arteriolosclerosis in one cat and hyperplastic arteriolosclerosis in the other. Rare foci of parenchymal microhemorrhages and necrosis were also observed. Systemic hypertension (especially severe or rapidly developing) accompanied by neurologic signs and the pathologic findings of diffuse brain edema with cerebral arteriolosclerosis are consistent with an etiologic diagnosis of hypertensive encephalopathy.

[Posterior reversible encephalopathy syndrome]

Posterior reversible encephalopathy syndrome refers to a neurological disorder characterized by headache, disorders of consciousness, visual disturbances, epileptic seizures, and subcortical vasogenic edema. About two thirds of patients develop neurological symptoms, which are associated with blood pressure fluctuations. One hypothesis is that hypertensive episodes cause autoregulatory failure, and values above the upper limit of cerebral autoregulation result in a breakthrough followed by hyperperfusion and blood-brain barrier dysfunction. In another hypothesis, endothelial dysfunction triggered by numerous factors including preeclampsia, immunosuppressive agents, chemotherapeutics, sepsis, or autoimmune disorders is thought to be the key pathomechanism. Endo- or exogenic toxic agents including pharmacological substances, cytokines, or bacterial toxins are supposed to trigger endothelial activation and dysfunction resulting in the release of vasoconstrictors, pro-inflammatory mediators, and vascular leakage. Diagnosis is usually based on clinical and neuroimaging findings that frequently show a bilateral, symmetric, and parietooccipital pattern. However, the diagnosis can often only be confirmed during the course of disease after excluding important differential diagnoses. Currently, there is no specific treatment available. Lowering of arterial blood pressure and eliminating the underlying cause usually leads to an improvement of clinical and neuroradiological findings. Admission to a critical care unit is required in about 40 % of patients due to complicating conditions including status epilepticus, cerebral vasoconstriction, ischemia, or intracerebral hemorrhage. Prognosis is favorable; in the majority of patients neurological deficits and imaging findings resolve completely.

Simultaneous and sequential hemorrhage of multiple cerebral cavernous malformations: a case report

BACKGROUND

The etiology of cerebral cavernous malformation hemorrhage is not well understood. Causative physiologic parameters preceding hemorrhagic cavernous malformation events are often not reported. We present a case of an individual with sequential simultaneous hemorrhages in multiple cerebral cavernous malformations with a new onset diagnosis of hypertension.

CASE PRESENTATION

A 42-year-old white man was admitted to our facility with worsening headache, left facial and tongue numbness, dizziness, diplopia, and elevated blood pressure. His past medical history was significant for new onset diagnosis of hypertension and chronic seasonal allergies. Serial imaging over the ensuing 8 days revealed sequential hemorrhagic lesions. He underwent suboccipital craniotomy for resection of the lesions located in the fourth ventricle and right cerebellum. One month after surgery, he had near complete resolution of his symptoms with mild residual vertigo but symptomatic chronic hypertension.

CONCLUSIONS

Many studies have focused on genetic and inflammatory mechanisms contributing to cerebral cavernous malformation rupture, but few have reported on the potential of hemodynamic changes contributing to cerebral cavernous malformation rupture. Systemic blood pressure changes clearly have an effect on angioma pressures. When considering the histopathological features of cerebral cavernous malformation architecture, changes in arterial pressure could cause meaningful alterations in hemorrhage propensity and patterns.

Risk of Stroke After the International Classification of Diseases-Ninth Revision Discharge Code Diagnosis of Hypertensive Encephalopathy

BACKGROUND AND PURPOSE

Although chronic hypertension is a well-established risk factor for stroke, little is known about stroke risk after hypertensive encephalopathy (HE), when neurologic sequelae of hypertension become evident. Therefore, we evaluated the risk of stroke after a diagnosis of HE.

METHODS

We identified all patients discharged from California, New York, and Florida emergency departments and acute care hospitals between 2005 and 2012 with a primary International Classification of Diseases, Ninth Edition, Clinical Modification discharge diagnosis of HE (437.2). Patients discharged with a primary diagnosis of seizure (345.x) served as negative controls, whereas patients with a primary diagnosis of transient ischemic attack (435.x) were positive controls. Our primary outcome was the composite of subsequent ischemic stroke or intracerebral hemorrhage. Kaplan-Meier survival statistics were used to calculate cumulative outcome rates, and Cox proportional hazard analysis was used to examine the association between index disease types and outcomes while adjusting for vascular risk factors.

RESULTS

We identified 8233 patients with HE, 191 091 with seizure, and 308 680 with transient ischemic attack. The 1-year cumulative rate of ischemic stroke or intracerebral hemorrhage after HE was 4.90% (95% confidence interval [CI], 4.45-5.40) when compared with 0.92% (95% CI, 0.88-0.97) after seizure and 4.49% (95% CI, 4.42-4.57) after transient ischemic attack. The risk of intracerebral hemorrhage was significantly elevated in those with HE (hazard ratio, 2.0; 95% CI, 1.7-2.5) but not in those with transient ischemic attack (hazard ratio, 1.0; 95% CI, 0.9-1.1), when compared with seizure patients.

CONCLUSIONS

Patients discharged with a diagnosis of HE face a high risk of future cerebrovascular events, particularly intracerebral hemorrhage.

Utility and Significance of Gadolinium-Based Contrast Enhancement in Posterior Reversible Encephalopathy Syndrome

BACKGROUND AND PURPOSE

Posterior reversible encephalopathy syndrome is a clinicoradiologic syndrome. Literature regarding associated factors and the prognostic significance of contrast enhancement in posterior reversible encephalopathy syndrome is sparse. This study set out to evaluate an association between the presence of enhancement in posterior reversible encephalopathy syndrome and various clinical factors in a large series of patients with this syndrome.

MATERIALS AND METHODS

From an MR imaging report search that yielded 176 patients with clinically confirmed posterior reversible encephalopathy syndrome between 1997 and 2014, we identified 135 patients who had received gadolinium-based contrast. The presenting symptoms, etiology, clinical follow-up, and maximum systolic and diastolic blood pressures within 1 day of MR imaging were recorded. MRIs were reviewed for parenchymal hemorrhage, MR imaging severity, and the presence and pattern of contrast enhancement. Statistical analyses evaluated a correlation between any clinical features and the presence or pattern of enhancement.

RESULTS

Of 135 included patients (67.4% females; age range, 7-82 years), 59 (43.7%) had contrast enhancement on T1-weighted MR imaging, the most common pattern being leptomeningeal (n = 24, 17.8%) or leptomeningeal plus cortical (n = 21, 15.6%). Clinical outcomes were available in 96 patients. No significant association was found between the presence or pattern of enhancement and any of the variables, including sex, age, symptom, MR imaging severity, blood pressure, or outcome (all P > .05 after Bonferroni correction).

CONCLUSIONS

The presence or pattern of enhancement in posterior reversible encephalopathy syndrome is not associated with any of the tested variables. However, an association was found between MR imaging severity and clinical outcome.

Posterior reversible encephalopathy syndrome--Insight into pathogenesis, clinical variants and treatment approaches

Posterior reversible encephalopathy syndrome is a rare clinicoradiological entity characterized by typical MRI findings located in the occipital and parietal lobes, caused by subcortical vasogenic edema. It was first described as a distinctive syndrome by Hinchey in 1996. Etiopathogenesis is not clear, although it is known that it is an endotheliopathy of the posterior cerebral vasculature leading to failed cerebral autoregulation, posterior edema and encephalopathy. A possible pathological activation of the immune system has been recently hypothesized in its pathogenesis. At clinical onset, the most common manifestations are seizures, headache and visual changes. Besides, tinnitus and acute vertigo have been frequently reported. Symptoms can be reversible but cerebral hemorrhage or ischemia may occur. Diagnosis is based on magnetic resonance imaging, in the presence of acute development of clinical neurologic symptoms and signs and arterial hypertension and/or toxic associated conditions with possible endotheliotoxic effects. Mainstay on the treatment is removal of the underlying cause. Further investigation and developments in endothelial cell function and in neuroimaging of cerebral blood flow are needed and will help to increase our understanding of pathophysiology, possibly suggesting novel therapies.

Modeling Cerebral Blood Flow Velocity During Orthostatic Stress

Cerebral autoregulation refers to the physiological process that maintains stable cerebral blood flow (CBF) during changes in arterial blood pressure (ABP). In this study, we propose a simple, nonlinear quantitative model with only four parameters that can predict CBF velocity as a function of ABP. The model was motivated by the viscoelastic-like behavior observed in the data collected during postural change from sitting to standing. Qualitative testing of the model involved analysis of dynamic responses to step-changes in pressure both within and outside the autoregulatory range, while quantitative testing was used to show that the model can fit dynamics observed in data measured from a healthy young and a healthy elderly subject. The latter involved analysis of structural and practical identifiability, sensitivity analysis, and parameter estimation. Results showed that the model is able to reproduce observed overshoot and adaptation and predict the different responses in the healthy young and the healthy elderly subject. For the healthy young subject, the overshoot was significantly more pronounced than for the elderly subject, but the recovery time was longer for the young subject. These differences resulted in different parameter values estimated using the two datasets.

The "neurovascular unit approach" to evaluate mechanisms of dysfunctional autoregulation in asphyxiated newborns in the era of hypothermia therapy

Despite improvements in obstetrical and neonatal care, and introduction of hypothermia as a neuroprotective therapy, perinatal brain injury remains a frequent cause of cerebral palsy, mental retardation and epilepsy. The recognition of dysfunction of cerebral autoregulation is essential for a real time measure of efficacy to identify those who are at highest risk for brain injury. This article will focus on the "neurovascular unit" approach to the care of asphyxiated neonates and will address 1) potential mechanisms of dysfunctional cerebral blood flow (CBF) regulation, 2) optimal monitoring methodology such as NIRS (near infrared spectroscopy), and TCD (transcutaneous Doppler), and 3) clinical implications of monitoring in the neonatal intensive care setting in asphyxiated newborns undergoing hypothermia and rewarming. Critical knowledge of the functional regulation of the neurovascular unit may lead to improved ability to predict outcomes in real time during hypothermia, as well as differentiate non-responders who might benefit from additional therapies.

Nitric oxide and cerebrovascular regulation

The cerebrovascular regulation involves highly complex mechanisms to assure that the brain is perfused at all times. These mechanisms depend on all components of the neurovascular units: neurons, glia, and vascular cells. All these cell types can produce nitric oxide (NO), a powerful vasodilator through different NO synthases. Many studies underlined the key role of NO in the maintenance of resting cerebral blood flow (CBF) as well as in the mechanisms that control cerebrovascular tone: autoregulation and neurovascular coupling. However, although the role of NO in the control of CBF has been largely investigated, the complexity of the NO system and the lack of specific NO synthase inhibitors led to still unresolved questions such as the origin of NO and the pathways by which it controls the vascular tone. In this chapter, the role of NO in the regulation of CBF is critically reviewed and discussed in the context of the neurovascular unit and the general principles of cerebrovascular regulation.

Hypertension and hypertensive encephalopathy

The definition of hypertension has continuously evolved over the last 50 years. Hypertension is currently defined as a blood pressure greater than 140/90mmHg. One in every four people in the US has been diagnosed with hypertension. The prevalence of hypertension increases further with age, affecting 75% of people over the age of 70. Hypertension is by far the most common risk factor identified in stroke patients. Hypertension causes pathologic changes in the walls of small (diameter<300 microns) arteries and arterioles usually at short branches of major arteries, which may result in either ischemic stroke or intracerebral hemorrhage. Reduction of blood pressure with diuretics, β-blockers, calcium channel blockers, and angiotensin-converting enzyme (ACE) inhibitors have all been shown to markedly reduce the incidence of stroke. Hypertensive emergency is defined as a blood pressure greater than 180/120mmHg with end organ dysfunction, such as chest pain, shortness of breath, encephalopathy, or focal neurologic deficits. Hypertensive encephalopathy is believed to be caused by acute failure of cerebrovascular autoregulation. Hypertensive emergency is treated with intravenous antihypertensive agents to reduce blood pressure by 25% within the first hour. Selective inhibition of cerebrovascular blood vessel permeability for the treatment of hypertensive emergency is beginning early clinical trials.

Central-variant posterior reversible encephalopathy syndrome: brainstem or basal ganglia involvement lacking cortical or subcortical cerebral edema

OBJECTIVE

Although posterior reversible encephalopathy syndrome (PRES) typically involves cortical or subcortical edema of the cerebrum, only individual cases have been described of a variant involving the central brainstem and basal ganglia and lacking cortical and subcortical edema. We evaluated FLAIR and T2-weighted images of 124 patients with confirmed PRES to determine the incidence of this uncommon variant, which we refer to as the "central variant"; to determine which structures are involved in this variant; and to determine the associated causes.

CONCLUSION

We found that five of the 124 patients (4%) with PRES had MR findings consistent with the central variant-that is, either brainstem or basal ganglia involvement and a lack of cortical or subcortical edema of the cerebrum. The thalami were involved in all five PRES patients with MR findings consistent with the central variant, but there was variable involvement of the posterior limb of the internal capsule (4/5), cerebellum (3/5), and periventricular white matter (3/5); in each patient, there was improvement both clinically and on MRI. The causes of PRES in these five patients were hypertension (n=2), cyclosporine (n=2), and eclampsia (n=1). The incidence of the central variant may be increasing because of an improving awareness of the diverse imaging patterns of PRES.

The speed of blood pressure fluctuations in patients with chronic obstructive pulmonary disease

BACKGROUND

Chronic obstructive pulmonary disease (COPD) has been associated with increased risk for cardiovascular disease but mechanisms underlying this association are incompletely understood. The speed of beat-to-beat changes in systolic blood pressure (vSBP) was found to be pronounced in patients with elevated cardiovascular risk. Although increased vSBP may thus be a contributing mechanism to cardiovascular morbidity, no data exist on vSBP in patients with COPD. Therefore, the purpose of this study was to evaluate whether there is an association between severity of COPD and vSBP.

METHODS

Resting beat-to-beat blood pressure was recorded during 5 min. vSBP was assessed by calculating the slopes of oscillatory fluctuations in SBP for different inter-beat intervals (IBI). Univariate and multivariate analyses were performed to evaluate the association between forced expiratory volume in 1 s (FEV1) and vSBP.

RESULTS

This study comprised 60 patients with COPD (24 females) with a mean [SD] FEV1 of 45.4 [22.7] %predicted and 34 healthy controls. Short-term fluctuations in SBP were more pronounced in patients with COPD compared to healthy controls. There was a significant inverse correlation between FEV1 and vSBP (r=-0.41, p=0.001). Even after adjustment for covariates in multivariate analysis, FEV1 was found to be independently associated with vSBP.

CONCLUSIONS

Patients with COPD are characterised by steeper blood pressure changes than healthy controls. The speed of fluctuations in SBP is associated with the severity of airflow limitation. Increased vSBP may be a mechanism underpinning the association between COPD and cardiovascular disease.