Non-invasive assessment of lung elastance in patients with acute respiratory distress syndrome.

BACKGROUND: Chest wall mechanics can be abnormal in patients with acute respiratory disease syndrome (ARDS). Therefore, partitioning respiratory system between lungs and chest wall at the bedside is useful to optimize ventilator settings. A non-invasive method for assessing lung elastance (EL), called lung barometry, was previously described on an animal model. METHODS: This prospective study was designed to compare EL assessed by lung barometry (ELLB) versus esophageal pressure (ELPeso). In sedated, paralyzed patients, PEEP was progressively increased from 5 to 40cmH2O then decreased from 40 to 5cmH2O by step of 5cmH2O every two minutes. ELLB was assessed for each step as the ratio between the change in PEEP and the induced end-expiratory lung volume change measured by direct spirometry. ELPeso was calculated from esophageal pressure measurement at each PEEP. EL and the ratio between EL and respiratory system elastance (ERS) calculated with the two methods were compared. RESULTS: Twenty six adult patients with early onset moderate or severe ARDS were included. There was a linear correlation between ELLB and ELPeso during the increase and decrease of PEEP (R²=0.26 and 0.42, respectively). Concordance using Bland and Altman method demonstrated bias and large limits of agreement during the increase (-0.5 cmH2O/L; -25 to 24 cmH2O/L) and during the decrease in PEEP (-0.3 cmH2O/L; -21 to 20 cmH2O/L). There were no linear correlation between ELLB/ERS and ELPeso/ERS during the increase and the decrease of PEEP (R²=0.00; R²=0.00, respectively). CONCLUSION: In ARDS patients, lung barometry method cannot be used instead of the esophageal pressure measurement to assess EL.

Growth curve of female collared peccaries (Pecari tajacu) raised in captivity in the Brazilian Amazon Region / Curva de crescimento de fêmeas cateto (Pecari tajacu) criados em cativeiro na Amazônia Brasileira

This work aims to determine the most suitable nonlinear model to describe the growth of female collared peccaries (Pecari tajacu). The monthly records of the weight of 10 captive female collared peccaries over a period of two years in the Brazilian Amazon Region were used. The growth models used were the Von Bertalanffy, Brody, Gompertz and Logistic. The parameters were estimated by using the NLIN procedure from the SAS application. The criteria used to verify the adjustment of the models were: asymptotic standard deviation (ASD); coefficient of determination (R²); average absolute residual deviation (ARD) and the asymptotic rate (AR). The Brody model and the Logistic model estimated the highest (19.44kg) and the lowest (19.18kg) asymptotic weight (A), indicating the lowest (0.0070kg/day) and the highest (0.0121kg/day) maturation rate (K). These results and the coefficients of phenotypic correlation that varied from -0.75 and -0.47 confirmed the antagonistic nature between these parameters. The Brody model estimated the lower value for ARD, a limiting factor for describing the lowest value for AR through this model. The Brody model showed the best adjustment for AR, although the other models also showed a suitable adjustment to the weight data of said species/gender. Based on the AR obtained in this work, the Brody model is recommended for adjusting the growth curve of the female collared peccaries. Depending on the estimated values, especially for K, this trait can be included in a selection index.

Com o objetivo de ajustar modelos não-lineares, foram utilizados registros mensais do peso de 10 fêmeas de cateto (Pecari tajacu) coletados durante dois anos, no criatório do campo experimental Álvaro Adolfo da Embrapa Amazônia Oriental, Belém, PA. Utilizaram-se os modelos de Von Bertalanffy, Brody, Gompertz e Logístico. Os parâmetros foram estimados usando o procedimento NLIN do aplicativo SAS. Os critérios utilizados para verificar o ajuste dos modelos foram: desvio padrão assintótico (ASD); coeficiente de determinação (R²); desvio médio absoluto dos resíduos (ARD) e o índice assintótico (AR). Os modelos Brody e Logístico estimaram, respectivamente, o maior (19,44kg) e o menor (19,18kg) peso assintótico (A), caracterizando a menor (0,0064kg/dia) e a maior (0,0113kg/dia) taxa de maturação (K), haja vista a natureza antagônica entre estes parâmetros, comprovada pela correlação fenotípica variando entre -0,75 à -0,47. O modelo Brody estimou o menor valor para o ARD, fator limitante para caracterizar o menor valor para o AR por este modelo. Considerando o AR, o modelo Brody apresentou o melhor ajuste, contudo, pelos valores encontrados, os demais modelos também apresentaram ajuste adequando aos dados ponderais da referida espécie/sexo. Com base no AR adotado neste trabalho, recomenda-se o modelo Brody para ajustar a curva de crescimento de fêmeas de cateto (Pecari tajacu). Em razão dos valores estimados, sobretudo, para a K, essa característica pode ser incluída em um índice de seleção. Contudo, estudos com grupos mais representativos e criados em outras condições se faz oportuno.

Pressure versus volume controlled modes in invasive mechanical ventilation.

The first generation of mechanical ventilators were controlled and cycled by pressure. Unfortunately, they did not allow control of the delivered tidal volume under changes in the dynamics of the respiratory system. This led to a second generation of ventilators that allowed volume control, hence favoring the ventilatory strategy based on normalization of the arterial gases. Studies conducted in the 1980s which related lung injury to the high ventilator pressures utilized while treating acute respiratory distress syndrome patients renewed interest in pressure-controlled mechanical ventilation. In addition, new evidence became available, leading to the development of pulmonary protective strategies aiming at preventing the progression of ventilator-induced lung injury. This review provides a detailed description of the control of pressure or volume using certain ventilatory modes, and offers a general view of their advantages and disadvantages, based on the latest available evidence.

Parâmetros genéticos da taxa de maturacão e do peso assintótico de fêmeas da raca Nelore / Genetic parameters of maturation rate and asymptotic weight of Nelore females

Utilizaram-se 14.563 pesagens de 1158 fêmeas da raca Nelore, nascidas entre 1984 e 1995, pertencentes a 10 fazendas, distribuídas em sete estados do Brasil. Com o objetivo de estabelecer um padrão médio de crescimento, obter parâmetros individuais das curvas e estimar os componentes de variância, herdabilidade e correlacões genéticas dos parâmetros das curvas, foram comparados os modelos de Von Bertalanffy, Brody, logístico e Gompertz. Foram utilizados o procedimento NLIN e o programa MTDFREML sob modelo animal em análise unicaráter e bicaráter. Os parâmetros médios dos pesos assintóticos (A) e das taxas de maturidade (K) foram: 515,06 e 0,071 para Von Bertalanffy; 552,77 e 0,045 para Brody; 501,11 e 0,097 para logístico, e 507,00 e 0,083 para Gompertz, respectivamente. As estimativas de herdabilidade para A e K foram de alta magnitude: 0,39 e 0,42 para Von Bertalanffy, 0,42 e 0,44 para Brody, 0,40 e 0,41 para logístico e 0,39 e 0,39 para Gompertz, respectivamente. As correlacões genéticas variaram entre -0,69 e -0,49. Todos os modelos foram adequados para descrever o crescimento. A ordem de escolha do melhor modelo para descrever a curva de crescimento foi: Brody, Von Bertalanffy, logístico e Gompertz. Essas características seriam passíveis de inclusão em índice de selecão para selecão de fêmeas Nelore.

[Can Helicobacter pylori infection be a risk factor for the severity of rheumatoid arthritis?]. / L'infezione da Helicobacter pylori può essere un fattore di rischio per la severità dell'artrite reumatoide?

AIM: In this study we assessed the effect of Helicobacter pylori eradication in patients with established rheumatoid arthritis (RA) in order to show a possible pathogenetic role of the infection in this disease. METHODS: We recruited 31 patients with variable RA activity. Of them, 15 were Hp-positive (12 F and 3 M, mean age 55 +/- 10.6 years) and 16 Hp-negative (13 F and 3 M, mean age 54.2 +/- 9.1 years) on the basis of the concomitant positive or negative findings of both CLO-test and histology performed on both antral and corpus biopsies. The infected group was treated and the bacterium was considered eradicated when both tests were negative a month after therapy. We have evaluated the disease activity at baseline and during a total follow-up period of 16 months with check-points every 4-months and compared clinical and laboratory findings between the Hp-negative and the eradicated groups. Both groups were being treated with NSAIDs and prednisolone (< or = 7.5 mg/die) or its equivalents. RESULTS: Hp-eradicated RA patients showed a progressive improvement overtime (p = 0.0009) of all clinical indices compared with baseline, while Hp-negative RA patients did not. At the 16-month checkpoint, the eradicated RA patients differed significantly (p < 0.006) from patients without Hp infection by all indices, except grip strength of the hands. Also all laboratory data improved significantly from baseline to the 16 month checkpoint (p < 0.03) within the Hp-eradicated group and between the two groups of eradicated and Hp-negative RA patients (p < 0.0007) except for Hb, aCL IgM and gamma-globulins. CONCLUSIONS: Our data suggest that Hp infection is implicated in the pathogenesis of RA. On the basis of our data, the eradication of Hp should be recommended in infected RA patients.

Anticardiolipin antibodies, free protein S levels and thrombosis: a survey in a selected population of rheumatoid arthritis patients.

OBJECTIVE: To investigate plasma levels of natural anticoagulant proteins such as protein S, protein C and antithrombin III in a selected population of patients with rheumatoid arthritis (RA) with and without anticardiolipin antibody (aCL) positivity, and to evaluate the possible relationships with an increased risk of thrombotic events in RA. METHODS: A total of 184 female RA patients attending our Extra-Articular Involvement RA Clinic were evaluated for aCL levels, total and free protein S, protein C and antithrombin III concentrations, and for the occurrence of thrombotic events. Patients were grouped as aCL positive (n = 35) and aCL negative (n = 149). RESULTS: Higher rates of venous and/or arterial thromboses were diagnosed in patients with RA compared to controls (P = 0.01). In particular, lower free protein S levels were found in aCL-positive patients with RA compared to both aCL-negative patients and controls (P = 0.001). Functional assays for protein C, antithrombin III as well as total protein S levels were found to be in the normal range in all patients and controls. CONCLUSION: The association observed between aCL positivity and decreased levels of free protein S in RA patients may represent one of the risk factors for thrombotic events.