A multicenter, randomized, double-blind trial of a new porcine surfactant in premature infants with respiratory distress syndrome / Ensaio clínico multicêntrico duplo-cego randomizado com um novo surfactante de origem porcina em prematuros com síndrome do desconforto respiratório

Objective To compare the efficacy and safety of a new porcine-derived pulmonary surfactant developed by Instituto Butantan with those of animal-derived surfactants commercially available in Brazil, regarding neonatal mortality and the major complications of prematurity in preterm newborns with birth weight up to 1500g and diagnosed with respiratory distress syndrome. Methods Neonates diagnosed with respiratory distress syndrome were randomized to receive either Butantan surfactant (Butantan group) or one of the following surfactants: Survanta® or Curosurf®. Newborns receiving Survanta® or Curosurf® comprised the control group. The main outcome measures were mortality rates at 72 hours and at 28 days of life; the typical complications of prematurity as evaluated on the 28th day of life were defined as secundary outcomes. Results No differences were observed between the Butantan (n=154) and control (n=173) groups in relation to birth weight, gestational age, sex, and prenatal use of corticosteroids, or in mortality rates both at 72 hours (14.19% versus 14.12%; p=0.98) and at 28 days (39.86% versus 33.33%; p=0.24) of life. Higher 1- and 5-minute Apgar scores were observed among control group newborns. No differences were observed as regards the secondary outcomes, except for greater need for supplemental oxygen and a higher incidence of interstitial pulmonary emphysema in the Butantan group. Conclusion The mortality rates at 72 hours and 28 days of life and the incidence of major complications of prematurity were comparable to those found with the animal-derived surfactants commercially available in Brazil, showing the efficacy and safety of the new surfactant in the treatment of respiratory distress syndrome ...

Objetivo Comparar a eficácia e a segurança de um novo surfactante pulmonar de origem porcina, desenvolvido pelo Instituto Butantan, com os surfactantes de origem animal disponíveis no país, em relação à mortalidade neonatal e às principais complicações da prematuridade, em prematuros com peso de nascimento até 1500g e diagnóstico de síndrome do desconforto respiratório. Métodos Recém-nascidos com diagnóstico de síndrome do desconforto respiratório foram randomizados para receber surfactante Butantan (Grupo Butantan) ou um dos seguintes surfactantes: Survanta® ou Curosurf®. Os recém-nascidos que receberam Survanta® ou Curosurf® formaram o Grupo Controle. Foram definidas, como variáveis primárias, as mortalidades com 72 horas e 28 dias de vida e, como variáveis secundárias, as principais complicações típicas da prematuridade, avaliadas no 28O dia de vida. Resultados Não foram observadas diferenças em relação ao peso de nascimento, idade gestacional, sexo e corticoide pré-natal, assim como em relação à mortalidade dos recém-nascidos dos Grupos Butantan (n=154) e Controle (n=173), tanto com 72 horas (14,19% versus 14,12%; p=0,98) como em 28 dias de vida (39,86% versus 33,33%; p=0,24). Foram observados maiores valores do boletim de Apgar de 1 e de 5 minutos entre os recém-nascidos do Grupo Controle. Os grupos não diferiram em relação às variáveis secundárias, exceto por uma maior necessidade de uso de oxigênio e de enfisema pulmonar intersticial no Grupo Butantan. Conclusão As taxas de mortalidade com 72 horas ...

Lung morphometry, collagen and elastin content: changes after hyperoxic exposure in preterm rabbits

INTRODUCTION: Elastic and collagen fiber deposition increases throughout normal lung development, and this fiber network significantly changes when development of the lung is disturbed. In preterm rats and lambs, prolonged hyperoxic exposure is associated with impaired alveolization and causes significant changes in the deposition and structure of elastic fibers. OBJECTIVES: To evaluate the effects of hyperoxic exposure on elastic and collagen fiber deposition in the lung interstitial matrix and in alveolarization in preterm rabbits. METHODS: After c-section, 28-day preterm New-Zealand-White rabbits were randomized into 2 study groups, according to the oxygen exposure, namely: Room air (oxygen = 21 percent) or Oxygen (oxygen > 95 percent). The animals were killed on day 11 and their lungs were analyzed for the alveolar size (Lm), the internal surface area (ISA), the alveoli number, and the density and distribution of collagen and elastic fibers. RESULTS: An increase in the Lm and a decrease in the alveoli number were observed among rabbits that were exposed to hyperoxia with no differences regarding the ISA. No difference in the density of elastic fibers was observed after oxygen exposure, however there were fewer collagen fibers and an evident disorganization of fiber deposition. DISCUSSION: This model reproduces anatomo-pathological injuries representing the arrest of normal alveolar development and lung architecture disorganization by just a prolonged exposition to oxygen. CONCLUSIONS: In the preterm rabbit, prolonged oxygen exposure impaired alveolization and also lowered the proportion of collagen fibers, with an evident fiber network disorganization.

Utilization of the lower inflection point of the pressure-volume curve results in protective conventional ventilation comparable to high frequency oscillatory ventilation in an animal model of acute respiratory distress syndrome

INTRODUCTION: Studies comparing high frequency oscillatory and conventional ventilation in acute respiratory distress syndrome have used low values of positive end-expiratory pressure and identified a need for better recruitment and pulmonary stability with high frequency. OBJECTIVE: To compare conventional and high frequency ventilation using the lower inflection point of the pressure-volume curve as the determinant of positive end-expiratory pressure to obtain similar levels of recruitment and alveolar stability. METHODS: After lung lavage of adult rabbits and lower inflection point determination, two groups were randomized: conventional (positive end-expiratory pressure = lower inflection point; tidal volume=6 ml/kg) and high frequency ventilation (mean airway pressures= lower inflection point +4 cmH2O). Blood gas and hemodynamic data were recorded over 4 h. After sacrifice, protein analysis from lung lavage and histologic evaluation were performed. RESULTS: The oxygenation parameters, protein and histological data were similar, except for the fact that significantly more normal alveoli were observed upon protective ventilation. High frequency ventilation led to lower PaCO2 levels. DISCUSSION: Determination of the lower inflection point of the pressure-volume curve is important for setting the minimum end expiratory pressure needed to keep the airways opened. This is useful when comparing different strategies to treat severe respiratory insufficiency, optimizing conventional ventilation, improving oxygenation and reducing lung injury. CONCLUSIONS: Utilization of the lower inflection point of the pressure-volume curve in the ventilation strategies considered in this study resulted in comparable efficacy with regards to oxygenation and hemodynamics, a high PaCO2 level and a lower pH. In addition, a greater number of normal alveoli were found after protective conventional ventilation in an animal model of acute respiratory distress syndrome.

Coelhos prematuros expostos à hiperoxia prolongada: um modelo para o estudo da displasia broncopulmonar / Preterm rabbits exposed to prolongued hyperoxia as a model for the study of bronchopulmonary dysplasia

Os modelos experimentais para o estudo da displasia broncopulmonar(DBP) são caros e de difícil manipulação. Com o objetivo de desenvolver um novo modelo animal, coelhos prematuros de 28 dias de gestação foram expostos ao oxigênio ³95 por cento por 7 ou 11 dias e comparados com animais mantidos em ar ambiente. O efeito da hiperoxia sobre o pulmão foi avaliado através de medidas de peso, volume, intecepto linear médio(Lm), área de superfície interna, número dos alvéolos, espessura do septo alveolar, proporção de água, fibras elásticas e colágenas. A exposição prolongada ao oxigênio ocasionou o bloqueio do crescimento e desenvolvimento pulmonar, com hipoalveolização, aumento do LM, maior espessamento septal e desorganização das fibras, reproduzindo as lesões características da DBP humana /The experimental models used for the study of bronchopulmonary dysplasia (BPD) are expensive and difficult to be handled. In order to develop a new animal model, 28 days gestation preterm rabbits were exposed to ³95 per cent oxygen for 7 or 11 days, and compared to room air. Hyperoxia effect was evalueted through body weight, lung volume, mean linear intercepts (MLI), internal gas-exchange surface area, alveoli number and septal thickness, water proportion, elastic and colagen fiber deposition. Oxygen exposure in premature rabbits arrested lung growth and development, reducing alveoli number, increasing MLI and alveolar septal thickening and disorganizating fibers deposition; reproducing the major histological BPD findings described in humans...

Characterization of newborns with nonimmune hydrops fetalis admitted to a neonatal intensive care unit

PURPOSE: To determine the incidence and characteristics of nonimmune hydrops fetalis in the newborn population. METHOD: A retrospective study of the period between 1996 and 2000, including all newborns with a prenatal or early neonatal diagnosis of nonimmune hydrops fetalis, based on clinical history, physical examination, and laboratory evaluation. The following were analyzed: prenatal follow-up, delivery type, gender, birth weight, gestational age, presence of perinatal asphyxia, nutritional classification, etiopathic diagnosis, length of hospital stay, mortality, and age at death. RESULTS: A total of 47 newborns with hydrops fetalis (0.42 percent of live births), 18 (38.3 percent) with the immune form and 29 (61.7 percent) with the nonimmune form, were selected for study. The incidence of nonimmune hydrops fetalis was 1 per 414 neonates. Data was obtained from 21 newborns, with the following characteristics: 19 (90.5 percent) were suspected from prenatal diagnosis, 18 (85.7 percent) were born by cesarean delivery, 15 (71.4 percent) were female, and 10 (47.6 percent) were asphyxiated. The average weight was 2665.9 g, and the average gestational age was 35 3/7 weeks; 14 (66.6 percent) were preterm; 18 (85.0 percent) appropriate delivery time; and 3 (14.3 percent) were large for gestational age. The etiopathic diagnosis was determined for 62 percent, which included cardiovascular (19.0 percent), infectious (9.5 percent), placental (4.8 percent), hematologic (4.7 percent), genitourinary (4.8 percent), and tumoral causes (4.8 percent), and there was a combination of causes in 9.5 percent. The etiology was classified as idiopathic in 38 percent. The length of hospital stay was 26.6 ± 23.6 days, and the mortality rate was 52.4 percent. CONCLUSIONS: The establishment of a suitable etiopathic diagnosis associated with prenatal detection of nonimmune hydrops fetalis can be an important step in reducing the neonatal mortality rate from this condition