Long-term sequelae in children surviving adult respiratory distress syndrome.

Nine children surviving severe adult respiratory distress syndrome were studied 0.9 to 4.2 years after the acute illness. They had received artificial ventilation for a mean of 9.4 days, with an Fio2 greater than 0.5 during a mean time of 34 hours and maximal positive end expiratory pressure levels in the range of 8 to 20 cm H2O. Three children had recurrent respiratory symptoms (moderate exertional dyspnea and cough), and two had evidence of fibrosis on chest radiographs. All patients had abnormal lung function; the most prominent findings were ventilation inequalities, as judged by real-time moment ratio analysis of multibreath nitrogen washout curves (abnormal in eight of nine patients) and hypoxemia (seven of nine). Lung volumes were less abnormal; one patient had restrictive and two had obstructive disease. A significant correlation between intensive care measures (Fio2 greater than 0.5 in hours and peak inspiratory plateau pressure) and lung function abnormalities (moment ratio analysis and hypoxemia) was found. A possibly increased susceptibility of the pediatric age group to the primary insult or respiratory therapy of adult respiratory distress syndrome is suggested.

Reliable tidal volume estimates at the airway opening with an infant monitor during high-frequency oscillatory ventilation.

OBJECTIVE: To assess the suitability of a hot-wire anemometer infant monitoring system (Florian, Acutronic Medical Systems AG, Hirzel, Switzerland) for measuring flow and tidal volume (Vt) proximal to the endotracheal tube during high-frequency oscillatory ventilation. DESIGN: In vitro model study. SETTING: Respiratory research laboratory. SUBJECT: In vitro lung model simulating moderate to severe respiratory distress. INTERVENTION: The lung model was ventilated with a SensorMedics 3100A ventilator. Vt was recorded from the monitor display (Vt-disp) and compared with the gold standard (Vt-adiab), which was calculated using the adiabatic gas equation from pressure changes inside the model. MEASUREMENTS AND MAIN RESULTS: A range of Vt (1-10 mL), frequencies (5-15 Hz), pressure amplitudes (10-90 cm H2O), inspiratory times (30% to 50%), and Fio2 (0.21-1.0) was used. Accuracy was determined by using modified Bland-Altman plots (95% limits of agreement). An exponential decrease in Vt was observed with increasing oscillatory frequency. Mean DeltaVt-disp was 0.6 mL (limits of agreement, -1.0 to 2.1) with a linear frequency dependence. Mean DeltaVt-disp was -0.2 mL (limits of agreement, -0.5 to 0.1) with increasing pressure amplitude and -0.2 mL (limits of agreement, -0.3 to -0.1) with increasing inspiratory time. Humidity and heating did not affect error, whereas increasing Fio2 from 0.21 to 1.0 increased mean error by 6.3% (+/-2.5%). CONCLUSIONS: The Florian infant hot-wire flowmeter and monitoring system provides reliable measurements of Vt at the airway opening during high-frequency oscillatory ventilation when employed at frequencies of 8-13 Hz. The bedside application could improve monitoring of patients receiving high-frequency oscillatory ventilation, favor a better understanding of the physiologic consequences of different high-frequency oscillatory ventilation strategies, and therefore optimize treatment.

Comparação entre dois métodos para a determinação do volume de escoamento superficial

A determinação do volume máximo de escoamento superficial é fundamental para o dimensionamento de diversos tipos de obras hidráulicas, constituindo o parâmetro de maior importância no projeto de sistemas de terraceamento em nível. A determinação incorreta do volume escoado superficialmente gera imprecisões no dimensionamento destes sistemas que, quando superdimensionados, apresentam elevado custo de instalação. Tendo em vista esses aspectos, o presente trabalho teve por objetivo comparar os valores de volume máximo de escoamento superficial, obtidos por meio do método empírico do número da curva, desenvolvido pelo Serviço de Conservação de Solos dos Estados Unidos, com aqueles obtidos por meio do método desenvolvido por Pruski e colaboradores, baseado em princípios consagrados na hidrologia. O desempenho dos dois métodos foi analisado com base nas condições pluviométricas correspondentes a Belo Horizonte e Uberlândia, para período de retorno de 10 anos. Evidenciaram-se grandes diferenças entre os valores de volume de escoamento superficial obtidos pelos dois métodos, as quais se mostraram mais acentuadas para maiores velocidades de infiltração de água no solo, tendo o método proposto por Pruski e colaboradores apresentado comportamento mais condizente com a realidade.

The functional neuroimaging correlates of psychogenic versus organic dystonia.

The neurobiological basis of psychogenic movement disorders remains poorly understood and the management of these conditions difficult. Functional neuroimaging studies have provided some insight into the pathophysiology of disorders implicating particularly the prefrontal cortex, but there are no studies on psychogenic dystonia, and comparisons with findings in organic counterparts are rare. To understand the pathophysiology of these disorders better, we compared the similarities and differences in functional neuroimaging of patients with psychogenic dystonia and genetically determined dystonia, and tested hypotheses on the role of the prefrontal cortex in functional neurological disorders. Patients with psychogenic (n = 6) or organic (n = 5, DYT1 gene mutation positive) dystonia of the right leg, and matched healthy control subjects (n = 6) underwent positron emission tomography of regional cerebral blood flow. Participants were studied during rest, during fixed posturing of the right leg and during paced ankle movements. Continuous surface electromyography and footplate manometry monitored task performance. Averaging regional cerebral blood flow across all tasks, the organic dystonia group showed abnormal increases in the primary motor cortex and thalamus compared with controls, with decreases in the cerebellum. In contrast, the psychogenic dystonia group showed the opposite pattern, with abnormally increased blood flow in the cerebellum and basal ganglia, with decreases in the primary motor cortex. Comparing organic dystonia with psychogenic dystonia revealed significantly greater regional blood flow in the primary motor cortex, whereas psychogenic dystonia was associated with significantly greater blood flow in the cerebellum and basal ganglia (all P < 0.05, family-wise whole-brain corrected). Group × task interactions were also examined. During movement, compared with rest, there was abnormal activation in the right dorsolateral prefrontal cortex that was common to both organic and psychogenic dystonia groups (compared with control subjects, P < 0.05, family-wise small-volume correction). These data show a cortical-subcortical differentiation between organic and psychogenic dystonia in terms of regional blood flow, both at rest and during active motor tasks. The pathological prefrontal cortical activation was confirmed in, but was not specific to, psychogenic dystonia. This suggests that psychogenic and organic dystonia have different cortical and subcortical pathophysiology, while a derangement in mechanisms of motor attention may be a feature of both conditions.

Balanço de água no volume de solo explorado pelo sistema radicular de uma planta de citros

A produtividade das culturas agrícolas, associada às condições climáticas e edáficas, depende da disponibilidade de água e nutrientes no solo em época e quantidades apropriadas. A falta ou excesso de água no solo são fatores limitantes ao crescimento vegetal e podem diminuir a produtividade. Portanto, estudos que levem a um melhor entendimento de como a água se comporta na zona radicular de uma cultura agrícola no campo são de importância indiscutível ao adequado manejo agrícola. O objetivo do presente trabalho foi avaliar o método do balanço de água no solo aplicado ao volume de solo explorado pelo sistema radicular de uma planta de citros, considerando cinco profundidades de solo e cinco distâncias horizontais do tronco em duas direções a partir do tronco (uma ao longo e outra perpendicular à linha de plantas) e, então, verificar a contribuição de cada uma das camadas de solo avaliadas à evapotranspiração real da planta. O experimento foi realizado num Latossolo Vermelho-Amarelo distrófico argissólico em um pomar de citros, no município de Piracicaba (SP), durante dois períodos, um seco (40 dias) e um chuvoso (37 dias). Para atender ao objetivo proposto, um conjunto de 25 tensiômetros (cinco profundidades x cinco distâncias do tronco) foi instalado ao longo da linha e um outro, idêntico, perpendicular à linha, em direção à entrelinha. A armazenagem foi calculada a partir das leituras dos dois conjuntos de 25 tensiômetros cujos potenciais mátricos determinados foram convertidos em umidades volumétricas pelas curvas de retenção da água no solo. A drenagem interna e a ascensão capilar foram estimadas a partir das leituras diárias dos tensiômetros e da função K(fim) (condutividade hidráulica em função do potencial mátrico), por meio da equação de Darcy-Buckingham. Esta função K(fim) para cada profundidade foi determinada pelo método do perfil instantâneo realizado em área adjacente. A precipitação pluvial foi medida por pluviômetro com aquisição automática de dados instalado na área. Os resultados obtidos mostraram que o método do balanço de água proposto foi adequado para avaliar quanto cada camada de solo da zona radicular da planta contribuiu para o consumo total de água (evapotranspiração real) da planta, nos dois períodos estudados. Nesse sentido, a camada de 0,00 a 0,60 m de profundidade mostrou ser a que a planta deva apresentar maior volume de raízes ativas, de acordo com sua maior contribuição ao consumo de água pela planta.

Robust volume-targeted balanced steady-state free-precession coronary magnetic resonance angiography in a breathhold at 3.0 Tesla: a reproducibility study.

BACKGROUND: Transient balanced steady-state free-precession (bSSFP) has shown substantial promise for noninvasive assessment of coronary arteries but its utilization at 3.0 T and above has been hampered by susceptibility to field inhomogeneities that degrade image quality. The purpose of this work was to refine, implement, and test a robust, practical single-breathhold bSSFP coronary MRA sequence at 3.0 T and to test the reproducibility of the technique. METHODS: A 3D, volume-targeted, high-resolution bSSFP sequence was implemented. Localized image-based shimming was performed to minimize inhomogeneities of both the static magnetic field and the radio frequency excitation field. Fifteen healthy volunteers and three patients with coronary artery disease underwent examination with the bSSFP sequence (scan time = 20.5 ± 2.0 seconds), and acquisitions were repeated in nine subjects. The images were quantitatively analyzed using a semi-automated software tool, and the repeatability and reproducibility of measurements were determined using regression analysis and intra-class correlation coefficient (ICC), in a blinded manner. RESULTS: The 3D bSSFP sequence provided uniform, high-quality depiction of coronary arteries (n = 20). The average visible vessel length of 100.5 ± 6.3 mm and sharpness of 55 ± 2% compared favorably with earlier reported navigator-gated bSSFP and gradient echo sequences at 3.0 T. Length measurements demonstrated a highly statistically significant degree of inter-observer (r = 0.994, ICC = 0.993), intra-observer (r = 0.894, ICC = 0.896), and inter-scan concordance (r = 0.980, ICC = 0.974). Furthermore, ICC values demonstrated excellent intra-observer, inter-observer, and inter-scan agreement for vessel diameter measurements (ICC = 0.987, 0.976, and 0.961, respectively), and vessel sharpness values (ICC = 0.989, 0.938, and 0.904, respectively). CONCLUSIONS: The 3D bSSFP acquisition, using a state-of-the-art MR scanner equipped with recently available technologies such as multi-transmit, 32-channel cardiac coil, and localized B0 and B1+ shimming, allows accelerated and reproducible multi-segment assessment of the major coronary arteries at 3.0 T in a single breathhold. This rapid sequence may be especially useful for functional imaging of the coronaries where the acquisition time is limited by the stress duration and in cases where low navigator-gating efficiency prohibits acquisition of a free breathing scan in a reasonable time period.

Relações da rugosidade superficial do solo com o volume de chuva e com a estabilidade de agregados em água

A rugosidade superficial do solo é afetada, dentre outros fatores, pelo tipo de preparo, volume de chuva e estabilidade dos agregados estruturais diante da ação destrutiva da água. Em um Inceptisol, num experimento de erosão sob chuva natural realizado há 15 anos, no Sul da região do Planalto Catarinense, Brasil, avaliou-se a rugosidade superficial, a qual foi expressa por meio dos índices: rugosidade (RR), tortuosidade (T) e diferença de elevação limite (LD), no cultivo do milho, em 2003, e no cultivo da aveia, em 2004, em cujos períodos experimentais precipitaram 229 e 350 mm de chuva, respectivamente. Além disso, em 2004, entre os dois cultivos, avaliou-se a estabilidade dos agregados em água, expressa pelo diâmetro médio ponderado (DMP) e diâmetro médio geométrico (DMG) dos agregados. Os tratamentos de sistemas de manejo do solo foram: preparo convencional (PC) com uma aração + duas gradagens; cultivo mínimo (CM) com uma escarificação + uma gradagem, e semeadura direta (SD), ambos cultivados com milho e aveia, além de um tratamento adicional sem cultivo do solo (SC) em preparo convencional com uma aração + duas gradagens. A rugosidade foi avaliada em cinco oportunidades no cultivo do milho e em quatro da aveia, sendo a primeira avaliação imediatamente após o preparo do solo, e as demais, em intervalos sucessivos de 15 dias. A rugosidade inicial do solo foi alta e diminuiu com o aumento do volume das chuvas nos tratamentos SC, PC e CM, enquanto, na SD, a rugosidade foi alta apenas no cultivo da aveia e apresentou variação muito pequena com o aumento da chuva. O SC apresentou a maior redução da rugosidade ao acaso, enquanto a menor redução ocorreu na SD. A rugosidade superficial foi reduzida da condição original, na qual não se retiraram os efeitos da pendente e das marcas do preparo do solo, para a condição ao acaso, na qual esses efeitos foram retirados. A rugosidade superficial ao acaso relacionou-se inversamente com o volume das chuvas naturais. O decaimento máximo da rugosidade ao acaso relacionou-se inversamente com o DMP e com o DMG dos agregados estruturais.

Hypertension is an independent predictor of mean platelet volume in patients with acute ischaemic stroke.

Introduction: Mean platelet volume (MPV) was shown to be significantly increased in patients with acute ischaemic stroke, especially in non-lacunar strokes. Moreover, some studies concluded that increased MPV is related to poor functional outcome after ischaemic stroke, although this association is still controversial. However, the determinants of MPV in patients with acute ischaemic stroke have never been investigated. Subjects and methods: We recorded the main demographic, clinical and laboratory data of consecutive patients with acute (admitted within 24 h after stroke onset) ischaemic stroke admitted in our Neurology Service between January 2003 and December 2008. MPV was generated at admission by the Sysmex XE-2100 automated cell counter (Sysmex Corporation, Kobe, Japan) from ethylenediaminetetraacetic acid blood samples stored at room temperature until measurement. The association of these parameters with MPV was investigated in univariate and multivariate analysis. Results: A total of 636 patients was included in our study. The median MPV was 10.4 ± 0.82 fL. In univariate analysis, glucose (β= 0.03, P= 0.05), serum creatinine (β= 0.002, P= 0.02), haemoglobin (β= 0.009, P < 0.001), platelet count (β=-0.002, P < 0.001) and history of arterial hypertension (β= 0.21, P= 0.005) were found to be significantly associated with MPV. In multivariate robust regression analysis, only hypertension and platelet count remained as independent determinants of MPV. Conclusions: In patients with acute ischaemic stroke, platelet count and history of hypertension are the only determinants of MPV.