Individual Patient Data Meta-Analysis of Dynamic Cerebral Autoregulation and Functional Outcome After Ischemic Stroke.

BACKGROUND: The relationship between dynamic cerebral autoregulation (dCA) and functional outcome after acute ischemic stroke (AIS) is unclear. Previous studies are limited by small sample sizes and heterogeneity. METHODS: We performed a 1-stage individual patient data meta-analysis to investigate associations between dCA and functional outcome after AIS. Participating centers were identified through a systematic search of the literature and direct invitation. We included centers with dCA data within 1 year of AIS in adults aged over 18 years, excluding intracerebral or subarachnoid hemorrhage. Data were obtained on phase, gain, coherence, and autoregulation index derived from transfer function analysis at low-frequency and very low-frequency bands. Cerebral blood velocity, arterial pressure, end-tidal carbon dioxide, heart rate, stroke severity and sub-type, and comorbidities were collected where available. Data were grouped into 4 time points after AIS: <24 hours, 24 to 72 hours, 4 to 7 days, and >3 months. The modified Rankin Scale assessed functional outcome at 3 months. Modified Rankin Scale was analyzed as both dichotomized (0 to 2 versus 3 to 6) and ordinal (modified Rankin Scale scores, 0-6) outcomes. Univariable and multivariable analyses were conducted to identify significant relationships between dCA parameters, comorbidities, and outcomes, for each time point using generalized linear (dichotomized outcome), or cumulative link (ordinal outcome) mixed models. The participating center was modeled as a random intercept to generate odds ratios with 95% CIs. RESULTS: The sample included 384 individuals (35% women) from 7 centers, aged 66.3±13.7 years, with predominantly nonlacunar stroke (n=348, 69%). In the affected hemisphere, higher phase at very low-frequency predicted better outcome (dichotomized modified Rankin Scale) at <24 (crude odds ratios, 2.17 [95% CI, 1.47-3.19]; P<0.001) hours, 24-72 (crude odds ratios, 1.95 [95% CI, 1.21-3.13]; P=0.006) hours, and phase at low-frequency predicted outcome at 3 (crude odds ratios, 3.03 [95% CI, 1.10-8.33]; P=0.032) months. These results remained after covariate adjustment. CONCLUSIONS: Greater transfer function analysis-derived phase was associated with improved functional outcome at 3 months after AIS. dCA parameters in the early phase of AIS may help to predict functional outcome.

Exploring Physiological Differences in Brain Areas Using Statistical Complexity Analysis of BOLD Signals.

The brain is a fundamental organ for the human body to function properly, for which it needs to receive a continuous flow of blood, which explains the existence of control mechanisms that act to maintain this flow as constant as possible in a process known as cerebral autoregulation. One way to obtain information on how the levels of oxygen supplied to the brain vary is through of BOLD (Magnetic Resonance) images, which have the advantage of greater spatial resolution than other forms of measurement, such as transcranial Doppler. However, they do not provide good temporal resolution nor allow for continuous prolonged examination. Thus, it is of great importance to find a method to detect regional differences from short BOLD signals. One of the existing alternatives is complexity measures that can detect changes in the variability and temporal organisation of a signal that could reflect different physiological states. The so-called statistical complexity, created to overcome the shortcomings of entropy alone to explain the concept of complexity, has shown potential with haemodynamic signals. The aim of this study is to determine by using statistical complexity whether it is possible to find differences between physiologically distinct brain areas in healthy individuals. The data set includes BOLD images of 10 people obtained at the University Hospital of Leicester NHS Trust with a 1.5 Tesla magnetic resonance imaging scanner. The data were captured for 180 s at a frequency of 1 Hz. Using various combinations of statistical complexities, no differences were found between hemispheres. However, differences were detected between grey matter and white matter, indicating that these measurements are sensitive to differences in brain tissues.

Detection of Blood CO2 Influences on Cerebral Hemodynamics Using Transfer Entropy.

Cerebral hemodynamics describes an important physiological system affected by components such as blood pressure, CO2 levels, and endothelial factors. Recently, novel techniques have emerged to analyse cerebral hemodynamics based on the calculation of entropies, which quantifies or describes changes in the complexity of this system when it is affected by a pathological or physiological influence. One recently described measure is transfer entropy, which allows for the determination of causality between the various components of a system in terms of their flow of information, and has shown positive results in the multivariate analysis of physiological signals. This study aims to determine whether conditional transfer entropy reflects the causality in terms of entropy generated by hypocapnia on cerebral hemodynamics. To achieve this, non-invasive signals from 28 healthy individuals who undertook a hyperventilation maneuver were analyzed using conditional transfer entropy to assess the variation in the relevance of CO2 levels on cerebral blood velocity. By employing a specific method to discretize the signals, it was possible to differentiate the influence of CO2 levels during the hyperventilation phase (22.0% and 20.3% increase for the left and right hemispheres, respectively) compared to normal breathing, which remained higher during the recovery phase (15.3% and 15.2% increase, respectively).

Analysis of cerebral blood flow entropy while listening to music with emotional content.

Objective. Music is one of the most sublime stimuli that human beings can experience. Despite being just an acoustic wave that exerts little physical influence on a subject, it triggers profound changes in emotions and physiological states. This study explores the possibility of detecting subtle changes in cerebral blood flow velocity in response to emotional reactions produced by different musical stimuli using multiscale entropy analysis.Approach. Cerebral blood flow signals were successfully recorded for 16 subjects while performing five different musical tasks. The entropy of each signal was estimated using multiscale sample entropy.Main results. This method has been shown to be capable of revealing the complexity of the internal dynamics of different physiological systems, which cannot be appreciated with classic approaches based on entropy on a single scale.Significance. Significant differences in entropy were found between two of the tasks, which suggests that intense cognitive activities with emotional content cause a decrease in the entropy of cerebral haemodynamics.

Non-linear models for the detection of impaired cerebral blood flow autoregulation.

The ability to discriminate between normal and impaired dynamic cerebral autoregulation (CA), based on measurements of spontaneous fluctuations in arterial blood pressure (BP) and cerebral blood flow (CBF), has considerable clinical relevance. We studied 45 normal subjects at rest and under hypercapnia induced by breathing a mixture of carbon dioxide and air. Non-linear models with BP as input and CBF velocity (CBFV) as output, were implemented with support vector machines (SVM) using separate recordings for learning and validation. Dynamic SVM implementations used either moving average or autoregressive structures. The efficiency of dynamic CA was estimated from the model's derived CBFV response to a step change in BP as an autoregulation index for both linear and non-linear models. Non-linear models with recurrences (autoregressive) showed the best results, with CA indexes of 5.9 ± 1.5 in normocapnia, and 2.5 ± 1.2 for hypercapnia with an area under the receiver-operator curve of 0.955. The high performance achieved by non-linear SVM models to detect deterioration of dynamic CA should encourage further assessment of its applicability to clinical conditions where CA might be impaired.

A new model-free index of dynamic cerebral blood flow autoregulation.

The classic dynamic autoregulatory index (ARI), proposed by Aaslid and Tiecks, is one of the most widely used methods to assess the efficiency of dynamic cerebral autoregulation. Although this index is often used in clinical research and is also included in some commercial equipment, it exhibits considerable intra-subject variability, and has the tendency to produce false positive results in clinical applications. An alternative index of dynamic cerebral autoregulation is proposed, which overcomes most of the limitations of the classic method and also has the advantage of being model-free. This new index uses two parameters that are obtained directly from the response signal of the cerebral blood flow velocity to a transient decrease in arterial blood pressure provoked by the sudden release of bilateral thigh cuffs, and a third parameter measuring the difference in slope of this response and the change in arterial blood pressure achieved. With the values of these parameters, a corresponding classic autoregulatory index value could be calculated by using a linear regression model built from theoretical curves generated with the Aaslid-Tiecks model. In 16 healthy subjects who underwent repeated thigh-cuff manoeuvres, the model-free approach exhibited significantly lower intra-subject variability, as measured by the unbiased coefficient of variation, than the classic autoregulatory index (p = 0.032) and the Rate of Return (p<0.001), another measure of cerebral autoregulation used for this type of systemic pressure stimulus, from 39.23%±41.91% and 55.31%±31.27%, respectively, to 15.98%±7.75%.

Guía de práctica clínica para el tratamiento de la agitación psicomotora y la conducta agresiva / Clinical practice guidelines for the treatment of psychomotor agitation and aggressive behavior

Se presenta la Guía de práctica clínica para el tratamiento de la agitación psicomotora y la conducta agresiva del Departamento de Emergencia del Instituto Nacional de Salud Mental ôHonorio Delgado û Hideyo Noguchiõ Lima, Perú, aprobada mediante la Resolución Directoral Nº 071-2013-DG/INSMõHD-HNõ.

We present the Clinical practice guidelines for the treatment of psychomotor agitation and aggressive behavior from the Emergency Department, Instituto Nacional de Salud Mental ôHonorio Delgado û Hideyo Noguchiõ Lima, Peru, approved by Resolución Directoral Nº 071-2013-DG/INSMõHD-HNõ.

Venturi easy ambient sonic-spray ionization.

The development and illustrative applications of an ambient ionization technique termed Venturi easy ambient sonic-spray ionization (V-EASI) is described. Its dual mode of operation with Venturi self-pumping makes V-EASI applicable to the direct mass spectrometric analysis of both liquid (V(L)-EASI) and solid (V(S)-EASI) samples. V-EASI is simple and easy to assemble, operating solely via the assistance of a sonic stream of nitrogen or air. The sonic gas stream causes two beneficial and integrated effects: (a) the self-pumping of solutions via the Venturi effect and (b) sonic-spray ionization (SSI) of analytes either in solution or resting on solid surfaces. In its liquid mode, V(L)-EASI is applicable to analytes in solution, forming negatively and/or positively charged intact molecular species in a soft fashion with little or no fragmentation. In its solid mode, V(S)-EASI relies on Venturi self-pumping of a proper SSI solvent solution in combination with SSI to form a stream of bipolar charged droplets that bombard the sample surface, causing desorption and ionization of the analyte molecules. As for its precursor technique (EASI), V-EASI generates bipolar droplets with considerably lower average charging, which increases selectivity for ionization with high signal-to-noise ratios and clean spectra dominated by single molecular species with minimal solvent ions. V-EASI also operates in a voltage-, heat-, and radiation-free fashion and is therefore free of thermal, electrical, or discharge interferences.

Comparación del estadío clínico de presentación del adenocarcinoma gástrico en Arequipa entre los periodos 1991-1992 y 2001-2002 / Comparison of the clinical stage of presentation of gastric adenocarcinoma in Arequipa between the periods 1991-1992 and 2001-2002

Objetivos: Comparar los estadíos de presentación del adenocarcinoma gástrico en Arequipa entre los periodos 1991-1992 y 2001-2002 e identificar posibles características epidemiológicas que estuvieran influyendo en el momento del diagnóstico. Material y métodos: El estudio fue transversal, retrospectivo, descriptivo y analítico. Se estudiaron 47 casos del primer periodo y 65 del segundo. Ambos periodos fueron comparados en cuanto a estadío de presentación y otras variables epidemiológicas. Resultados: Aunque en ambos periodos la gran mayoría de casos debutaron en estadío IV (87 por ciento y 72 por ciento, respectivamente), se observó, en el segundo periodo, una reducción considerable de casos diagnosticados en estadíos avanzados (IIIB y IV), en comparación al primero; además hubo un aumento de casos diagnosticados en estadíos tempranos (IA, IB, II y IIIA). Los casos de early cáncer ascendieron de 2 por ciento a 9 por ciento. La única variable que presentó diferencia significativa entre periodos fue el porcentaje de pacientes sometidos a endoscopía, siendo mayor en el segundo. Conclusiones: Las cifras encontradas muestran que, a pesar de la variación positiva, aún se detecta en Arequipa el adenocarcinoma gástrico en estadíos muy avanzados, probablemente por falta de equipos e infraestructura moderna.

Estudio de hipertensión arterial en un servicio de urgencia / Study in arteria hypertension in an emergency service

La hipertensión arterial (HTA) es una patología de alta prevalencia en la población general y está relacionada directamente con múltiples afecciones que son frecuentemente atendidas en servicios de urgencia. Su manejo agudo si bien ha sido normado, no siempre es llevado a cabo en forma adecuada. Se estudió en forma retrospectiva la incidencia de HTA (definida como PAS>160 y/o PAD>100 mm Hg) en el Servicio de Urgencia del Hospital Clínico Universidad de Chile, entre el 1 de enero y el 30 de junio del año 2000. Se evaluó para cada paciente el peso, la edad, la presión arterial (agrupando hallazgos, urgencias y emergencias hipertensivas) y frecuencia cardíaca al ingreso, diagnóstico, forma de presentación y tratamiento. A partir de los resultados concluimos que la HTA es una patología de presentación frecuente en nuestro Servicio de Urgencia. Un gran porcentaje corresponde a hallazgos hipertensivos que no requieren tratamiento específico. Existe aún un significativo uso de Nifedipino de acción corta, pese a que no es recomendado