Tratamiento antiagregante plaquetario oral para el ictus isquémico agudo: una revisión Cochrane / Oral antiplatelet therapy for acute ischaemic stroke: a Cochrane review

Pregunta de la revisión. Queríamos comparar la seguridad y la eficacia del tratamiento antiplaquetario oral frente a placebo o ningún tratamiento en personas con ictus isquémico agudo para ver si los antiplaquetarios orales reducían el número de muertes y mejoraban los resultados a largo plazo en los supervivientes. Fundamento. La mayoría de los ictus están causados por una obstrucción repentina de una arteria del cerebro que suele deberse a un coágulo de sangre (lo que se denomina ictus isquémico). El tratamiento inmediato con antiagregantes plaquetarios, como la aspirina, puede evitar la formación de nuevos coágulos y mejorar así la recuperación tras el ictus. Sin embargo, los antiagregantes plaquetarios también pueden provocar hemorragias cerebrales, lo que podría anular sus efectos beneficiosos. Características del estudio. Se identificaron 11 estudios, hasta agosto de 2020, para su inclusión en la revisión. Estos estudios incluyeron 42.226 participantes. Tres eran nuevos ensayos desde la última actualización. Como en la versión anterior de esta revisión, dos estudios aportaron el 96% de los datos. La mayoría de los participantes en la revisión eran ancianos, con una proporción significativa de más de 70 años. Los hombres y las mujeres estaban representados casi por igual en los ensayos. Parecía haber alguna variación en la gravedad del accidente cerebrovascular entre los ensayos incluidos. La duración programada del tratamiento varió de 5 días a 3 meses y el periodo de seguimiento programado varió de 10 días a 6 meses. Resultados clave. La aspirina, en dosis de 160 mg a 300 mg diarios, iniciada en las 48 horas siguientes a la aparición de los síntomas del ictus, salvó vidas y redujo el riesgo de que se produjera un nuevo ictus en las dos primeras semanas... (AU)

Tratamiento antiagregante plaquetario oral para el ictus isquémico agudo: una revisión Cochrane / Oral antiplatelet therapy for acute ischaemic stroke: a Cochrane review

Pregunta de la revisión. Queríamos comparar la seguridad y la eficacia del tratamiento antiplaquetario oral frente a placebo o ningún tratamiento en personas con ictus isquémico agudo para ver si los antiplaquetarios orales reducían el número de muertes y mejoraban los resultados a largo plazo en los supervivientes. Fundamento. La mayoría de los ictus están causados por una obstrucción repentina de una arteria del cerebro que suele deberse a un coágulo de sangre (lo que se denomina ictus isquémico). El tratamiento inmediato con antiagregantes plaquetarios, como la aspirina, puede evitar la formación de nuevos coágulos y mejorar así la recuperación tras el ictus. Sin embargo, los antiagregantes plaquetarios también pueden provocar hemorragias cerebrales, lo que podría anular sus efectos beneficiosos. Características del estudio. Se identificaron 11 estudios, hasta agosto de 2020, para su inclusión en la revisión. Estos estudios incluyeron 42.226 participantes. Tres eran nuevos ensayos desde la última actualización. Como en la versión anterior de esta revisión, dos estudios aportaron el 96% de los datos. La mayoría de los participantes en la revisión eran ancianos, con una proporción significativa de más de 70 años. Los hombres y las mujeres estaban representados casi por igual en los ensayos. Parecía haber alguna variación en la gravedad del accidente cerebrovascular entre los ensayos incluidos. La duración programada del tratamiento varió de 5 días a 3 meses y el periodo de seguimiento programado varió de 10 días a 6 meses. Resultados clave. La aspirina, en dosis de 160 mg a 300 mg diarios, iniciada en las 48 horas siguientes a la aparición de los síntomas del ictus, salvó vidas y redujo el riesgo de que se produjera un nuevo ictus en las dos primeras semanas... (AU)

Directional sensitivity of dynamic cerebral autoregulation during spontaneous fluctuations in arterial blood pressure at rest.

Directional sensitivity, the more efficient response of cerebral autoregulation to increases, compared to decreases, in mean arterial pressure (MAP), has been demonstrated with repeated squat-stand maneuvers (SSM). In 43 healthy subjects (26 male, 23.1 ± 4.2 years old), five min. recordings of cerebral blood velocity (bilateral Doppler ultrasound), MAP (Finometer), end-tidal CO2 (capnograph), and heart rate (ECG) were obtained during sitting (SIT), standing (STA) and SSM. A new analytical procedure, based on autoregressive-moving average models, allowed distinct estimates of the autoregulation index (ARI) by separating the MAP signal into its positive (MAP+D) and negative (MAP-D) derivatives. ARI+D was higher than ARI-D (p < 0.0001), SIT: 5.61 ± 1.58 vs 4.31 ± 2.16; STA: 5.70 ± 1.24 vs 4.63 ± 1.92; SSM: 4.70 ± 1.11 vs 3.31 ± 1.53, but the difference ARI+D-ARI-D was not influenced by the condition. A bootstrap procedure determined the critical number of subjects needed to identify a significant difference between ARI+D and ARI-D, corresponding to 24, 37 and 38 subjects, respectively, for SSM, STA and SIT. Further investigations are needed on the influences of sex, aging and other phenotypical characteristics on the phenomenon of directional sensitivity of dynamic autoregulation.

Cerebrovascular responses to somatomotor stimulation in Parkinson's disease: A multivariate analysis.

Parkinson's disease (PD) is a common neurodegenerative disorder, yet little is known about cerebral haemodynamics in this patient population. Previous studies assessing dynamic cerebral autoregulation (dCA), neurovascular coupling (NVC) and vasomotor reactivity (VMR) have yielded conflicting findings. By using multi-variate modelling, we aimed to determine whether cerebral blood flow (CBF) regulation is impaired in PD patients.55 healthy controls (HC) and 49 PD patients were recruited. PD subjects underwent a second recording following a period of abstinence from their anti-Parkinsonian medication. Continuous bilateral transcranial Doppler in the middle cerebral arteries, beat-to-beat mean arterial blood pressure (MAP; Finapres), heart rate (HR; electrocardiogram), and end-tidal CO2 (EtCO2; capnography) were measured. After a 5-min baseline period, a passive motor paradigm comprising 60 s of elbow flexion was performed. Multi-variate modelling quantified the contributions of MAP, ETCO2 and neural stimulation to changes in CBF velocity (CBFV). dCA, VMR and NVC were quantified to assess the integrity of CBF regulation.Neural stimulation was the dominant input. dCA, NVC and VMR were all found to be impaired in the PD population relative to HC (p < 0.01, p = 0.04, p < 0.01, respectively). Our data suggest PD may be associated with depressed CBF regulation. This warrants further assessment using different neural stimuli.

Oral antiplatelet therapy for acute ischaemic stroke.

BACKGROUND: In people with acute ischaemic stroke, platelets become activated and can cause blood clots to form and block an artery in the brain, resulting in damage to part of the brain. Such damage gives rise to the symptoms of stroke. Antiplatelet therapy might reduce the volume of brain damaged by ischaemia and also reduce the risk of early recurrent ischaemic stroke, thereby reducing the risk of early death and improving long-term outcomes in survivors. However, antiplatelet therapy might also increase the risk of fatal or disabling intracranial haemorrhage. OBJECTIVES: To assess the efficacy and safety of immediate oral antiplatelet therapy (i.e. started as soon as possible and no later than two weeks after stroke onset) in people with acute presumed ischaemic stroke. SEARCH METHODS: We searched the Cochrane Stroke Group Trials Register, CENTRAL, MEDLINE Ovid, Embase Ovid, and two trials registers, and performed forward reference/cited reference searching in August 2020. SELECTION CRITERIA: Randomised controlled trials (RCTs) comparing oral antiplatelet therapy (started within 14 days of the stroke) with control in people with definite or presumed ischaemic stroke. DATA COLLECTION AND ANALYSIS: Two review authors independently applied the inclusion criteria and assessed trial quality. For the included trials, they extracted and cross-checked the data. They assessed risk of bias of each study using the Risk of Bias 1 (RoB1) tool and overall certainty of the evidence for each outcome using the GRADE approach. MAIN RESULTS: We included 11 studies involving 42,226 participants. Three new trials have been added since the last update (743 participants). As per the previous version of this review, two trials testing aspirin 160 mg to 300 mg once daily, started within 48 hours of onset, contributed 96% of the data. The risk of bias was low. The maximum follow-up was six months. With treatment, there was a decrease in death or dependency at the end of follow-up (odds ratio (OR) 0.95, 95% confidence interval (CI) 0.91 to 0.99; 7 RCTs, 42,034 participants; moderate-certainty evidence). For every 1000 people treated with aspirin, 13 people would avoid death or dependency (number needed to treat for an additional beneficial outcome 79). AUTHORS' CONCLUSIONS: Antiplatelet therapy with aspirin 160 mg to 300 mg daily, given orally (or by nasogastric tube or per rectum in people who cannot swallow) and started within 48 hours of onset of presumed ischaemic stroke, significantly decreased death and dependency, and reduced the risk of early recurrent ischaemic stroke without a major risk of early haemorrhagic complications; long-term outcomes were improved.

Directional sensitivity of dynamic cerebral autoregulation in squat-stand maneuvers.

Dynamic cerebral autoregulation (CA), the transient response of cerebral blood flow (CBF) to rapid changes in arterial blood pressure (BP), is usually modeled as a linear mechanism. We tested the hypothesis that dynamic CA can display nonlinear behavior resulting from differential efficiency dependent on the direction of BP changes. Cerebral blood velocity (CBV) (transcranial Doppler), heart rate (HR) (three-lead ECG), continuous BP (Finometer), and end-tidal CO2 (capnograph) were measured in 10 healthy young subjects during 15 squat-stand maneuvers (SSM) with a frequency of 0.05 Hz. The protocol was repeated with a median (interquartile range) of 44 (35-64) days apart. Dynamic CA was assessed with the autoregulation index (ARI) obtained from CBV step responses estimated with an autoregressive moving-average model. Mean BP, HR, and CBV were different (all P < 0.001) between squat and stand, regardless of visits. ARI showed a strong interaction ( P < 0.001) of SSM with the progression of transients; in general, the mean ARI was higher for the squat phase compared with standing. The changes in ARI were partially explained by concomitant changes in CBV ( P = 0.023) and pulse pressure ( P < 0.001), but there was no evidence that ARI differed between visits ( P = 0.277). These results demonstrate that dynamic CA is dependent on the direction of BP change, but further work is needed to confirm if this finding can be generalized to other physiological conditions and also to assess its dependency on age, sex and pathology.

The cerebrocardiovascular response to periodic squat-stand maneuvers in healthy subjects: a time-domain analysis.

Squat-stand maneuvers (SSMs) have been used to improve the coherence of transfer function analysis (TFA) estimates during the assessment of dynamic cerebral autoregulation (dCA). There is a need to understand the influence of peripheral changes resulting from SSMs on cerebral blood flow, which might confound estimates of dCA. Healthy subjects ( n = 29) underwent recordings at rest (5-min standing) and 15 SSMs (0.05 Hz). Heart rate (three-lead ECG), end-tidal CO2 (capnography), blood pressure (Finometer), cerebral blood velocity (CBV; transcranial Doppler, middle cerebral artery), and the angle of the thigh (tilt sensor) were measured continuously. The response of CBV to SSMs was decomposed into the relative contributions of mean arterial pressure (MAP), resistance-area product (RAP), and critical closing pressure (CrCP). Upon squatting, a rise in MAP (83.6 ± 21.1% contribution) was followed by increased CBV. A dCA response could be detected, determined by adjustments in RAP and CrCP (left hemisphere) with peak contributions of 24.8 ± 12.7% and 27.4 ± 22.8%, respectively, at different times during SSMs. No interhemispheric differences were detected. During standing, the contributions of MAP, RAP, and CrCP changed considerably. In conclusion, the changes of CBV subcomponents during repeated SSMs indicate a complex response of CBV to SSMs that can only be partially explained by myogenic mechanisms. More work is needed to clarify the potential contribution of other cofactors, such as breath-to-breath changes in Pco2, heart rate, stroke volume, and the neurogenic component of dCA. NEW & NOTEWORTHY Here, we describe the different contributions to the cerebral blood flow response after squat-stand maneuvers. Furthermore, we demonstrate the complex interaction of peripheral and cerebral parameters for the first time. Moreover, we show that the cerebral blood velocity response to squatting is likely to include a significant metabolic component.

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

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