Patient state index and cerebral blood flow changes during shoulder arthroscopy in beach chair position / Patient State Index e alterações do fluxo sanguíneo cerebral durante artroscopia do ombro em posição de cadeira de praia

Abstract Background and objectives: The aim of the study were to demonstrate the possible hemodynamic changes and cerebral blood flow alterations in patients who were positioned from supine to beach chair position; and to detect if the position change causes any cortical activity alteration as measured by the 4-channeled electroencephalography monitor. Methods: 35 patients were included. Before the induction, mean arterial pressure and patient state index values were recorded (T0). After the intubation, doppler-ultrasonography of the patients’ internal carotid and vertebral arteries were evaluated to acquire cerebral blood flow values from the formula. In supine position, mean arterial pressure, patient state index and cerebral blood flow values were recorded (T1) and the patient was positioned to beach chair position. After 5 min all measurements were repeated (T2). Measurements of patient state index and mean arterial pressure were repeated after 20 (T3), and 40 (T4) min. Results: There was a significant decrease between T0 and T1 in heart rate (80.5 ± 11.6 vs. 75.9 ± 14.4 beats/min), MAP (105.8 ± 21.9 vs. 78.9 ± 18.4 mmHg) and PSI (88.5 ± 8.3 vs. 30.3 ± 9.7) (all p < 0.05). Mean arterial pressure decreased significantly after position change, and remained decreased, compared to T1. The overall analysis of patient state index values (T1-T4) showed no significant change; however, comparing only T1 and T2 resulted in a statically significant decrease in patient state index. There was a significant decrease in cerebral blood flow after beach chair position. Conclusion: Beach chair position was associated with a decrease in cerebral blood flow and patient state index values. Patient state index was affected by the gravitational change of the cerebral blood flow; however, both factors were not directly correlated to each other. Moreover, the decrease in patient state index value was transient and returned to normal values within 20 min.

Resumo Justificativa e objetivos: Demonstrar as possíveis alterações hemodinâmicas e do fluxo sanguíneo cerebral (FSC) em pacientes que foram posicionados de supinação para cadeira de praia (CP) e detectar se a mudança de posição causa alguma alteração na atividade cortical como mensurado pelo monitor de EEG com quatro canais. Métodos: Foram incluídos 35 pacientes. Antes da indução, os valores da PAM e do IEP foram registrados (T0). Após a intubação, ultrassonografias com Doppler da carótida interna e artérias vertebrais dos pacientes foram avaliadas para adquirir os valores do FSC a partir da fórmula. Em supinação, os valores da PAM, IEP e FSC foram registrados (T1) e o paciente foi posicionado em CP. Após cinco minutos, todas as mensurações foram repetidas (T2). As mensurações do IEP e PAM foram repetidas após 20 (T3) e 40 minutos (T4). Resultados: Houve uma diminuição significativa entre T0 e T1 na FC (80,5 ± 11,6 vs. 75,9 ± 14,4 bpm), PAM (105,8 ± 21,9 vs. 78,9 ± 18,4 mmHg) e IEP (88,5 ± 8,3 vs. 30,3 ± 9,7) (p < 0,05 para todos). A PAM diminuiu significativamente após a mudança de posição e permaneceu diminuída em relação a T1. A análise global dos valores do IEP (T1-T4) não mostrou mudança significativa, mas a comparação de apenas T1 e T2 resultou em redução estatisticamente significativa do IEP. Houve redução significativa do FSC após o posicionado em CP. Conclusão: O posicionado em CP foi associado à diminuição do FSC e dos valores do IEP. O IEP foi afetado pela mudança gravitacional do FSC; no entanto, ambos os fatores não estavam diretamente correlacionados. Além disso, a diminuição do valor do IEP foi transitória e voltou aos valores normais dentro de 20 minutos.

Neuro – functional and endocrine findings in patients with post-traumatic stress disorder

The authors studied the neuro-functional findings demonstrated by SPECT in a group of 7 patients diagnosed with post traumatic stress disorder (PTSD) and their correlation with endocrinologic and clinical variables. Brain perfusion was assessed using SPECT Tc99m – ECD. The Davidson Trauma Scale (DTS) for post traumatic stress disorder and the abbreviated version of the Beck Depression Inventory (BDI) were used to corroborate clinical impressions. Endocrine measures included: T3, total T4, TSH and cortisol levels. Neuro-functional findings included abnormal radiopharmaceutical uptake in regions involved in the recovery of verbal memories and executive functions (frontal and pre-frontal cortex), and limbic system. No endocrine alterations affecting thyroid or cortisol levels were found. The broad distribution of neuro-functional abnormalities causes us to hypothesize a diffuse etiologic mechanism, possibly involving a dysfunction in the permeability of the blood-brain barrier due to an underlying inflammatory process.

Hypocapnia Attenuates, and Nitrous Oxide Disturbs the Cerebral Oximetric Response to the Rapid Introduction of Desflurane

The aim of this study was to develop a nonlinear mixed-effects model for the increase in cerebral oximetry (rSO2) during the rapid introduction of desflurane, and to determine the effect of hypocapnia and N2O on the model. Twelve American Society of Anesthesiologist physical status class 1 and 2 subjects were allocated randomly into an Air and N2O group. After inducing anesthesia, desflurane was then increased abruptly from 4.0 to 12.0%. The PET(CO2), PET(DESF) and rSO2 were recorded at 12 predetermined periods for the following 10 min. The maximum increase in rSO2 reached +24-25% during normocapnia. The increase in rSO2 could be fitted to a four parameter logistic equation as a function of the logarithm of PET(DESF). Hypocapnia reduced the maximum response of rSO2, shifted the EC50 to the right, and increased the slope in the Air group. N2O shifted the EC50 to the right, and reduced the slope leaving the maximum rSO2 unchanged. The N2O-effects disappeared during hypocapnia. The cerebrovascular reactivity of rSO2 to CO2 is still preserved during the rapid introduction of desflurane. N2O slows the response of rSO2. Hypocapnia overwhelms all the effects of N2O.

Bipolar disorder complicated by selfmutilation: neurofunctional changes demonstrated by Tc99mHMPAO Neuro SPECT

We report neurofunctional changes in patients with selfmutilation and bipolar disorder. We compared a sample of 29 patients with selfmutilation and bipolar disorder with a group of 20 patients with bipolar disorder without selfmutilation. Furthermore we had an additional control of 22 patients with Major Depression without selfmutilation. Among the findings in selfmutilation, increased anterior dorsal-ventral thalamic perfusion stands out, this is associated with decreased perfusion in the perilimbic area (areas 24, 32 and 23 of Brodmann). There are multiple reports relating in animals and humans selfmutilation with hypoalgesia, anesthesia and disestesias; an hypothesis can be formulated relating self mutilation phenomena with a dysfunction of thalamus and perilimbic circuits associated with nosoceptive circuits and somato-psychic conscience.

Memória de procedimentos e SPECT cerebral: avaliação de fluxo sanguíneo cerebelar e em córtex pré-frontal durante uma tarefa visuo-motora / Procedural memory and brain SPECT: blood flow evaluation in the cerebellum and pre-frontal cortex during a visuo-motor task

O objetivo deste estudo foi avaliar o fluxo sanguíneo cerebral no córtex cerebelar (4 sub-regiões) e no córtex pré-frontal, em repouso e durante uma tarefa motora. A amostra foi composta por 8 sujeitos saudáveis, ambos os sexos, entre 23 e 36 anos. O grupo foi submetido a tarefa visuo-motora (memória implícita) que consistia na ação de desviar um submarino de supostas minas que percorriam a tela do monitor. Para avaliar a perfusão, foi utilizado o método de análise semi-quantitativa para imagens de SPECT cerebral - 99mTc-ECD. Os resultados evidenciaram aumento de atividade nas áreas de interesse durante a realização da tarefa. Em conclusão, quatro sub-regiões do córtex cerebelar e ambos os hemisférios do córtex pré-frontal apontaram uma ativação simultânea durante a tarefa. Ainda, e conforme estudos prévios, nossos resultados sugerem um modo de operação em paralelo do sistema nervoso central, no intuito de integrar uma informação sensorial e motora.

The objective of the present study was to evaluate the cerebral blood flow in the cerebellar (4 sub-regions) and pre-frontal cortex, when subjects were in rest and during a motor task performance. The sample consisted of 8 healthy subjects, male or female, between 23 and 36 of age. The visuo-motor task _ implicit memory _ requires the subjects to navigate and swerve a graphic submarine from missiles that run on the screen. Semi-quantitative analysis with brain SPECT (99mTc-ECD) was used to evaluate regional perfusion. The results revealed an increased activity in all areas of interest during motor task. In conclusion, four sub-regions of cerebellar cortex and both pre-frontal hemispheres showed a simultaneous activation during task. Moreover, our findings suggest as seen in previous experiments that the central nervous system operates in a parallel fashion, in order to integrate sensory and motor information.

NeuroSPECT demonstrates increased cortical function in alzheimer’s disease patients for at least two years after omental transposition neurosurgery

Se ha comunicado mejoría clínica después del implante quirúrgico de Omento (delantal de los epiplones) en el cerebro en varias condiciones neurológicas que incluyen Infarto cerebral, Encefalitis, Transecciones de la médula espinal y enfermedad de Alzheimer's. La explicación fisiopatológica de estas mejorías no es conocida pero puede relacionarse con la presencia de Células Madres y factores de crecimiento en el Omento que tendrían efectos sobre la angiogénesis, neurogénesis y sobrevida neuronal. El presente trabajo describe los cambios en la actividad cerebral en dos pacientes con diagnóstico de Enfermedad de Alzheimer's confirmado por biopsia, cuya evolución clínica había entrado a una fase de rápida progresión antes del trasplante de Omento. Los pacientes fueron evaluados psicométricamente mediante la escala de clínica de severidad demencial , desde el punto de vista cognitivo el MMSE examination y Neurospect sequencial con HMPAO medido durante 22 y 42 meses respectivamente. La severidad de la demencia mejoró durante dos o más años, mientras la actividad cortical en áreas bajo, adyacente y contralateral al Omento implantado aumentó en una o dos desviaciones standard sobre los niveles pre-operativos del paciente (el máximo aumento fue un 21 por ciento, cuatro desviaciones standard). En el paciente con menor severidad de demencia se observó a los 22 meses post-trasplante que el cingulado posterior demostraba un aumento de perfusión de 20 por ciento comparado con el nivel pre-operativo. Esto es notable si consideramos que el Omento no tenía un contacto directo con la corteza cingulada posterior que se ve envuelta en las fases iniciales de la Enfermedad de Alzheimer's (Braak y Braak etapas 3-4). Estos hallazgos justifican investigación respecto de los mecanismos por los cuales el Omento puede mejorar la actividad cerebral cortical y las funciones clínicas durante dos o más años en la enfermedad de Alzheimer's.

Densidad neuronal en la corteza visual primaria (area 17(, de dos especies de roedores silvestres / Neuronal density in primary visual cortex (17 visual area), in two wild rodent species

Diversos estudios experimentales demuestran que modificaciones medioambientales (por ejemplo: nutricionales y lumínicas), pueden producir alteraciones en el desarrollo normal de la corteza visual y sus conexiones. Por otro lado, es posible que en condiciones naturales, las especies animales hayan desarrollado adaptaciones a las distintas condiciones de luminosidad en que realizan su actividad. Por ende, la finalidad de este trabajo, fue estudiar la corteza visual primaria (área 17), de dos especies de roedores silvestres, relacionados filogenéticamente, pero con diferentes períodos de actividad; Abrothrix olivaceus (n=7) y Phyllotis darwini (n=7), con el propósito de evidenciar cambios detectados a través de la medición de la densidad neuronal, mediante la técnica del disector óptico, en cortes de 40µm de grosor, incluidos en celoidina y teñidos con cresyl violeta (Nissl). A. olivaceus, el cual presenta un periodo de actividad continuo en la zona central de Chile, evidenció una densidad neuronal menor (34.75 x 104 ± 1.35 x 104 neuronas/mm3) que la observada en P. darwini (37.23 x 104 ± 2.20 x 104 neuronas/mm3), especie de actividad nocturna en la misma región del país; siendo lo anterior estadísticamente significativo (t=2.54; p<0.05). Las diferencias encontradas se relacionarían con el tipo de conducta que presentan ambas especies, dado principalmente por las características de luminosidad en que se desenvuelven, así como también, de otros factores que se relacionarían con este parámetro, como son la relación predador-presa y la alimentación, entre otros.

Effect of dichloracetate on infarct size in a primate model of focal cerebral ischaemia.

Acidosis is a major contributing factor towards spread of the ischaemic focus in the brain. Drugs that increase pyruvate dehydrogenase activity could decrease the formation of lactic acidosis. The sodium salt of dichloracetic acid (DCA) has been found to be effective in reducing lactate. This study was undertaken to study the efficacy of DCA in reducing infarct size in experimental focal ischaemia in monkeys. Macaca radiata monkeys in the treatment group were given 35 mg per kilogram of dichloracetate intravenously immediately before occluding and interrupting the middle cerebral artery, and the control group was given saline as placebo under similar conditions. Mean infarct size expressed as a percentage of the size of the hemisphere in all the three brain slices was 35.38 in the control group as against l2.06 in the treated group (p=0. 0008).

Glucose transport in cerebral microvessels during Plasmodium yoelii nigeriensis infection in mice.

Plasmodium yoelii infected cerebral micro vessels of mice registered a significant increase in D-[U-14C] Glucose transport as compared to normal microvessels which was found to be time, temperature and concentration dependent. Metabolic inhibitors galactose, manose, 2-deoxy glucose and D-glucose showed noticeable inhibition of the same.

Effects of decreased cerebral perfusion pressure on cerebral hemodynamics, brain cell membrane function and energy metabolism during the early phase of experimental Escherichia coli meningitis in the newborn piglet

In this study, we tested the hypothesis that decreased cerebral perfusion pressure (CPP) induces cerebral ischemia and worsen brain damage in neonatal bacterial meningitis. Meningitis was induced by intracisternal injection of 10(9) colony forming units of Escherichia coli in 21 newborn piglets. Although CPP decreased significantly at 8 hr after bacterial inoculation, deduced hemoglobin (HbD), measured as an index of changes in cerebral blood flow by near infrared spectroscopy, did not decrease significantly. In correlation analyses, CPP showed significant positive correlation with brain ATP and inverse correlation with brain lactate levels. CPP also correlated positively with HbD and oxidized cytochrome aa3 (Cyt aa3) by near infrared spectroscopy. However, CPP did not show significant correlation with cerebral cortical cell membrane Na+,K+-ATPase activity, nor with levels of lipid peroxidation products. In summary, decreased CPP observed in this study failed to induce cerebral ischemia and further brain injury, indicating that cerebrovascular autoregulation is intact during the early phase of experimental neonatal bacterial meningitis.

Efectos del cloruro de sodio hiperosmolar intravenoso sobre el flujo sanguíneo de diversos órganos de la rata / Effects of hyperosmotic sodium chloride on blood flow of several organs of the rat

En ratas anestesiadas con uretano se estudió el efecto de la infusión endovenosa de cloruro de sodio hiperosmolar (CSH), al 10% 4 ml. kg-1, sobre hematocrito, presión arterial media y flujo sanguíneo en corteza renal, corteza cerebral, hígado y músculo esquelético. El flujo sanguíneo fue determinado con el método del clearance de hidrógeno de Auckland, efectuándose una determinación basal y otra a los 15 minutos de inyectado el CSH. Se calculó la resistencia vascular dividiendo la presión arterial por el flujo ssanguíneo. (Se consideró significativa una P < 0.05). El flujo sanguíneo aumentó significativamente por efecto del CSH en corteza cerebral, corteza renal e hígado, no detectándose modificaciones en el flujo sanguíneo del músculo esquelético. El CSH produjo aumento de presión arterial media en todos los grupos estudiados, excepto en el grupo en que se midió el flujo sanguíneo cortical cerebral. La resistencia vascular disminuyó en corteza cerebral e hígado, permaneciendo constante en corteza renal y músculo esquelético; en el grupo de animales vagotomizados la resistencia vascular en el músculo esquelético aumentó significativamente. El CSH produjo un descenso significativo del hematocrito. Los resultados obtenidos, salvo el observado en animales vagotomizados, son compatibles con los efectos descriptos por otros autores que emplearon CSH en experimentos con otras especies animales. También son compatibles con los efectos descriptos en seres humanos con el empleo de CSH en el tratamiento del shock hipovolémico refractario