Increased levels of reactive oxygen species in platelets and platelet-derived microparticles and the risk of respiratory failure in HIV/AIDS patients

Respiratory failure (RF) is the main cause of hospital admission in HIV/AIDS patients. This study assessed comorbidities and laboratory parameters in HIV/AIDS inpatients with RF (N = 58) in relation to those without RF (N = 36). Tuberculosis showed a huge relative risk and platelet counts were slightly higher in HIV/AIDS inpatients with RF. A flow cytometry assay for reactive oxygen species (ROS) showed lower levels in platelets of these patients in relation to the healthy subjects. However, when stimulated with adrenaline, ROS levels increased in platelets and platelet-derived microparticles of HIV/AIDS inpatients, which may increase the risk of RF during HIV and tuberculosis (HIV-TB) coinfection.

Entendendo melhor a insuficiência respiratória aguda / A better understanding of acute respiratory failure

A insuficiência respiratória aguda (IRpA) é uma síndrome potencialmente grave, constituindo uma das principais indicações de internação em unidades de terapia intensiva. Embora diferentes condições clínicas possam evoluir com IRpA, todas apresentarão comprometimento nas trocas gasosas que caracterizarão a síndrome.O conhecimento da fisiologia das trocas gasosas e os mecanismos pelos quais elas podem ser alteradas permite compreender a fisiopatologia da IRpA e as repercussões dos diferentes distúrbios sobre os gases arteriais. Este conhecimento permite a interpretação adequada da gasometria arterial e de indicadores derivados da mesma, facilitando a condução dos pacientes com IRpA, tanto em relação ao diagnóstico etiológico, quanto ao tratamento de suporte.Estes conceitos da fisiologia das troas gasosas e da fisiopatologia da IRpA e suas aplicações clínicas serão revisados neste artigo...

Acute respiratory failure (ARF) is a potentially severe syndrome, which is a common indication for admission to an intensive care unit. Although the ARF can be caused by different clinical conditions, all of them will present gas exchange impairments that will characterize the syndrome.By knowing the gas exchanges physiology and the mechanisms by which they can be impaired, one can understand the physiopathology of the ARF and how it can compromise the arterial gases. This knowledge allows the correct interpretation of arterial blood gases and other useful indicators, such as the alveolar-arterial oxygen gradient, which help us to manage patients with ARF, both in their diagnosis, and in their supportive treatment.These concepts about the gas exchange physiology and the ARF physiopathology, and their clinical relevance, will be discussed in this article...

Ventilación mecánica no invasiva en pacientes con falla respiratoria aguda hipoxémica no hipercápnica / Noninvasive ventilation in patients with acute hypoxemic (non-hypercapnic) respiratory failure

Objetivo: Determinar que parámetros predictivos de éxito de la ventilación mecánica no invasiva (VNI) son aplicables en pacientes con falla respiratoria aguda hipoxémica no hipercápnicos post 24 horas de iniciada la VNI. Material y Método: Se analizaron retrospectivamente 54 pacientes que estuvieron hospitalizados en la UCI neuroquirúrgica del Hospital G. Grant Benavente (HGGB) entre el período agosto de 2002 a julio de 2004. Cuarenta y seis de ellos con indicación médica de asistencia ventilatoria mecánica no invasiva, modalidad BiPAP, con registro de gases arteriales (GSA) a lo menos cada 24 horas. Se registró sexo, edad, puntaje de APACHE II, TISS modificado, días de VM, días de VNI, IPAP, EPAP, modalidad VNI, GSA basales (día cero), GSA a las 24 horas (día uno), SatO2, PaO2/FiO2. También se registró diagnóstico causal de la falla respiratoria aguda por la cual se indicó la VNI. Resultado: De los 46 pacientes analizados y debidamente registrados, en 7 de ellos (15,2 por ciento) la técnica fracasó y en 39 pacientes (84,8 por ciento) la técnica fue exitosa. Se procedió a llevar a cabo un análisis de regresión logística con el propósito de determinar cuáles variables diferenciaban de mejor forma a los pacientes del grupo A (éxito) y del grupo B (fracaso). Se llevaron a cabo una serie de análisis de regresión logística sobre las variables indicadas, que permitieron establecer que sólo las variables PaO2 y PaO2/FiO2 contribuían significativamente a la predicción de los resultados en la variable criterio (grupo). Los resultados del análisis de regresión logística para la variable PaO2, mostraron un valor c2 razón de verosimilitud de c2(A) = 80,1 mm Hg (p <0,001), altamente significativo, con una sensibilidad de 64,1 por ciento y una especificidad de 71,4 por ciento (valor crítico: 80,1 mmHg). En la variable PaO2/Fi02, se observa que el modelo con esta única variable como predictor presenta un valor en el estadístico c2 razón de verosimilitud de c2(A) = 190 (p <0,001) que resulta altamente significativo, con una sensibilidad de 71,8 por ciento y una especificidad de 85,7 por ciento (valor crítico: 190). Conclusión: Estos resultados indican que aquellos pacientes que obtienen valores en la variable PaO2 y PaO2/FiO2 por sobre el valor crítico, tienen una mayor probabilidad de pertenecer al grupo de los pacientes para los que la intervención resulta ser exitosa.

Risk factors for hypoxemia and respiratory failure in respiratory syncytial virus bronchiolitis.

Respiratory syncytial virus (RSV) bronchiolitis is a common infection in young children and may result in hospitalization. We examined the incidence of, and risk factors associated with, hypoxemia and respiratory failure in 216 children aged < 24 months admitted consecutively for proven RSV bronchiolitis. Hypoxemia was defined as SpO2 < 90% in room air and severe RSV bronchiolitis requiring intubation and ventilation was categorized as respiratory failure. Corrected age at admission was used for premature children (gestation < 37 weeks). Hypoxemia was suffered by 31 (14.3%) children. It was more likely to occur in children who were Malay (OR 2.56, 95%CI 1.05-6.23, p=0.03) or premature (OR 6.72, 95%CI 2.69-16.78, p<0.01). Hypoxemia was also more likely to develop in children with failure to thrive (OR 2.96, 95%CI 1.28-6.82, p<0.01). The seven (3.2%) children who were both premature (OR 11.94, 95%CI 2.50-56.99, p<0.01) and failure to thrive (OR 6.41, 95%CI 1.37-29.87, p=0.02) were more likely to develop respiratory failure. Prematurity was the only significant risk factor for hypoxemia and respiratory failure by logistic regression analysis (OR 1.17, 95%CI 1.06-1.55, p<0.01 and OR 1.14 95%CI 1.02-2.07, p=0.02 respectively). Prematurity was the single most important risk factor for both hypoxemia and respiratory failure in RSV bronchiolitis.

Sleep disordered breathing in chronic obstructive pulmonary disease.

We prospectively studied sleep disordered breathing in 50 consecutive patients (39 males) with chronic obstructive pulmonary disease (COPD) with chronic respiratory failure (CRF) (n=33) and without CRF (n=17) by performing polysomnography. Patients with CRF had a lower mean nocturnal oxygen saturation (SaO2 %) (88.6+/-6.7 vs. 96.3+/-0.8; p=0.0001) and a lower minimal nocturnal SaO2 (73.6+/-12.0 vs. 84.3+/-7.3; p=0.002) compared to those without CRF, suggesting that patients with CRF tend to have more severe drops in nocturnal SaO2. Patients with CRF also had a lower FEV1 (% predicted) (p=0.01) and PEFR (% predicted) (p=0.031) compared to those without CRF suggesting an indirect relation to the oxygen saturation. Other pulmonary functions were comparable between both the groups. Among patients with and without CRF, the total sleep time (minutes); the rapid eye movement (REM) stage (% of total sleep time); the non-rapid eye movement (NREM) stage (% of total sleep time) were comparable (p=NS). Only three of the 50 patients with COPD had a significant (>5) apnea-hypopnea index (AHI) (total no. of apneas + total no. of hypopneas/ total sleep time [(hours) = AHI] and these three patients had a mean BMI = 27.7 which was higher than the mean BMI of the whole group (21.1). The AHI was comparable in patients with and without respiratory failure. Multiple regression analysis revealed a positive correlation between AHI and the neck circumference (r=0.41; p=0.005) and BMI (r=0.31; p=NS). There was a small but statistically insignificant negative correlation between AHI and neck length (r= -0.28; p=NS). We conclude that, BMI per se contributes to the AHI and nocturnal desaturation in patients with COPD.

Uso do suporte ventilatório com pressäo positiva contínua em vias aéreas (CPAP) por meio de máscara nasofacial no tratamento da insuficiência respiratória aguda / Continuous positive airway pressure (CPAP) by face mask to treat acute respiratory failure

Objetivo. O objetivo dos autores foi avaliar o efeito da ventilaçäo com CPAP oferecida por meio de máscara nasofacial como método de suporte ventilatório em pacientes com insuficiência respiratória aguda com critérios de indicaçäo para intubaçäo traqueal. Casuística e Método. Foram estudados 11 pacientes com idade média de 41,3 anos em insuficiência respiratória aguda internados na Unidade Respiratória do Hospital Säo Paulo - Escola Paulista de Medicina. A admissäo, era colhida gasometria arterial em ar ambiente e monitorizava-se freqüência respiratória (f), freqüência cardíaca (FC) e pressäo arterial (PA). Os mesmos parâmetros eram avaliados após oxigenoterapia via máscara facial aberta e com máscara facial de CPAP usando PEEP de 5cm H2O. Resultados. Com o uso de CPAP através de máscara nasofacial, houve melhora significativa dos níveis de PaO2 e diminuiçäo da freqüência respiratória (<0,05), quando comparados aos valores em ar ambiemte e com máscara facial aberta. Conclusäo. Este trabalho permitiu concluir que a máscara facial de CPAP com 5cm H2O foi eficiente em melhorar a oxigenaçäo arterial e diminuir a freqüência respiratória dos pacientes com insuficiência respiratória aguda, proporcionando-lhes maior conforto, constituindo uma medida terapêutica capaz de evitar o suporte ventilatório invasivo.

¿Es necesario determinar la fracción plasmática del contenido de oxígeno para calcular la derivación intrapulmonar? Reporte preliminar / Is it necessary to determinate the plasmatic oxygen content for the calculation of the intrapulmonary shunt? Preliminary report

Introducción: la estimación del contenido de O2 requiere de la saturación de la oxihemoglobina y del O2 disuelto en la sangre arterial y venosa para el cálculo de la ecuación clásica de la derivación intrapulmonar (Qsp/Qt). Objetivo: establecer una correlación entre la ecuación clásica de Qsp/Qt y una fórmula abreviada (Qsa/Qt). Pacientes y métodos: hicimos un estudio retrospectivo de 19 pacientes de la UCI (nueve mujeres, 10 hombres, edad media 49.6 ñ 14 años). A todos los pacientes se les colocaron catéteres arteriales pulmonares y sistémicos. Se les efectuó determinación de gases en sangre, mediciones hemodinámicas y cáculo de Qsp/Qt y Qsa/Qt. El oxígeno disuelto en sangre se eliminó de la ecuación del contenido de O2, cuando se utilizó Qsa/Qt. Resultados: Qsp/Qt fue 34.05 ñ 13.25 por ciento y Qsa/Qt 37.24 ñ 12.95 por ciento (p=0.434). Se observó una correlación muy alta entre Qsp/Qt (r=0.993). Conclusión: la estimación de la derivación intrapulmonar es posible si se elimina la participación del oxigeno disuelto en la sangre

Evaluation of five commercial kits for free thyroxine estimation by comparison with equilibrium dialysis method in nonthyroidal illness.

Five commercial kits for estimating FT4 in serum of 59 euthyroid control and 38 patients with severe NTI were studied: one non analog method (Gammacoat two step RIA, Clinical Assay) and four different analog methods (Amerlex-M RIA, Amersham; Enzymun test competitive enzyme immunoassay, Boehringer Mannheim; Amerlite chemiluminescence immunoassay, Kodak Clinical Diagnostics; Berilux chemiluminescence immunoassay, Behring) compared with equilibrium dialysis (Eq) method. Serum FT4 estimates in NTI patients measured by all commercial kits in this study yielded results comparable with those by equilibrium dialysis. The proportions of serum FT4 values concordant with FT4 (Eq) in each kit were 76.3, 76.3, 76.3, 68.4 and 78.9 per cent respectively. The percentage of NTI patients who had serum FT4 values lower than the reference levels of the methods used were 21.2, 26.3, 7.9, 15.8, 18.4 and 18.4 per cent respectively. No patient with low serum FT4 (Eq) level had subnormal or high serum TSH value. However, 4 out of 6 patients with high serum FT4 (Eq) values had depressed serum TSH values. All of them also had elevation of serum FT4 estimates measured by all kits. Serum FT4 estimates measured by all methods correlated well with FT4 (Eq) levels within the NTI group.