The present study was performed to determine whether ongoing oxidative stress in some BPD infants contributes to their increased energy expenditure leading to growth failure. The study consisted of two parts. The first is a descriptive census of BPD infants (n = 38) followed at the outpatient clinics at The Montreal Children's Hospital (MCH). The second is a cross-sectional study of fifteen patients wherein anthropometric parameters, energy intake, and oxidative stress measures (red cell glutathione (GSH) and plasma malondialdehyde (MDA)) were assessed. Nine infants with growth failure were compared to six thriving infants with respect to their nutritional and oxidative stress status. Growth failure was defined as weight for age and weight for height for age less than the tenth percentile (z score $ leq - 1).$ Results revealed that the prevalence of growth failure in the BPD infants followed at MCH ranged between 45% and 55%. The mean ($ pm$ SD) energy intakes for thriving and failing to thrive infants expressed as a percent of the recommended nutrient intake were 104 $ pm$ 46% and 133 $ pm$ 35% respectively. Six infants had reduced mean ($ pm$ SD) blood glutathione per hemoglobin (3.63 $ pm$ 0.37 umol/g) compared to adult controls (6.57 $ pm$ 1.04 umol/g). Four of the six infants had growth failure while two were thriving. Fourteen Infants including all failing to thrive infants had elevated mean ($ pm$ SD) plasma MDA levels compared to adult controls (129 $ pm$ 48 vs 55 $ pm$ 3 nmol/l). Differences in oxidative stress markers were not observed between the two groups. These results suggest that growth failure is associated with an increase in caloric consumption and not with a decrease in caloric intake. The preliminary findings on oxidative stress markers suggest a depletion of the GSH antioxidant in some infants and marked lipid peroxidation in the BPD population.

Thesis (Ph. D.)--University of Washington, 1995. / Vita. Includes bibliographical references (leaves [109]-121).

Orientadores: Maria Aparecida Marques dos Santos Mezzacappa, José Dirceu Ribeiro / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-18T05:32:42Z (GMT). No. of bitstreams: 1 Mendes_ThaisdeBarros_D.pdf: 2709718 bytes, checksum: 980600cf933c0edd1c628440ceb42c40 (MD5) Previous issue date: 2010 / Resumo: Recém-nascidos (RN) com displasia broncopulmonar (DBP) apresentam alta frequência de tratamento para doença do refluxo gastroesofágico (DRGE). O agravamento da evolução desta doença pulmonar é atribuído à associação entre as duas entidades. Em virtude das indefinições quanto à ocorrência da DRGE em RN com DBP e dadas as possíveis consequências sobre a sua morbidade, bem como as altas frequências de tratamento clínico, considerou-se ser de interesse estudar a presença de anormalidades da monitorização prolongada do pH esofágico em RN com e sem DBP. Objetivos- Determinar a prevalência de índice de refluxo (IR) ?10% na monitorização prolongada do pH esofágico em RNMBP com e sem o diagnóstico de DBP e estabelecer fatores associados. Métodos- Foi realizado um estudo prospectivo e de corte transversal com um componente longitudinal. Foram selecionados 35 casos com DBP e 15 sujeitos para o grupo de comparação que foram submetidos à monitorização prolongada do pH esofágico distal, no período de abril de 2004 a dezembro de 2008. Foram analisadas as variáveis demográficas, de evolução pós-natal, referentes a procedimentos e medicamentos no período neonatal, bem como os escores de gravidade clínica e radiológica da DBP e de gravidade da doença pulmonar na primeira semana de vida. Foram empregados os testes de Qui-quadrado e Exato de Fisher para as variáveis categóricas, e para as numéricas o teste U de Mann-Whitney. Em seguida foi realizada a análise por regressão logística univariada e múltipla para determinar o odds-ratio (OR) e o seu intervalo de confiança (IC) de 95%. Resultados- A prevalência de IR ?10% nos grupos com e sem DBP foi de 65,7% e 93,3%, respectivamente. O peso ao nascer foi o fator preditor independente de risco para o IR ?10% (OR 1,769 IC95% 1,172-2,669). Conclusão- Foi encontrada uma prevalência de IR ?10% em RN com DBP de 65,7% e no grupo de comparação de 93,3% sem sinais clínicos de DRGE. A chance de IR ?10% aumentou em 76,9% a cada aumento de 100 gramas no PN. Os resultados deste estudo permitem concluir que a prevalência de IR ?10% não é maior em RN com DBP do que no grupo de comparação. RN assintomáticos ou com apneia da prematuridade podem apresentar IR ?10%, sendo assim o diagnóstico de DRGE baseado nos resultados da monitorização do pH esofágico e a indicação de qualquer modalidade terapêutica precisa ser criteriosa até que se definam quais são os RN que necessitam de tratamento / Abstract: Neonates with bronchopulmonary dysplasia (BPD) present high frequency of treatment for gastroesophageal reflux disease (GERD). The relationship between these illnesses is controversy. Due to indefinations for ocorrency of GERD in newborns with BPD and considering the possible consequences about his morbidity so as the high frequency of clinical treatment, seems to us important to study the presence of abnormalities in the prolonged esophageal pH monitoring in neonates with and without BPD. Objectives- To determine the prevalence pH esophageal monitoring alterations in very low birth weight infants with and without BPD and establish associated factors for reflux index (RI) ?10%. Methods- A prospective, cross-sectional study, with a longitudinal component was realized, including 35 newborns with BPD and 15 subjects for the comparison group, that were submitted to 24 hours esophageal pH monitoring and studied from April 2004 to December 2008. Were evaluated variables demographics, postnatal evolution, procedures and medications used in the neonatal period, scores of clinical and radiologic severity and initial lung disease in the first week of life. For the statistic analysis were utilized the chi-square test and the Fisher's exact test for the category variables, and Mann-Whitney's test for numerical variables. Multiple logistic regression was used for to determine odds-ratio (OR) and confidence interval (CI) of 95%. Results- The prevalence of RI ?10% in the groups with e without BPD was 65.7% and 93.3%, respectively. The birth weight (BW) was the independent predictor factor for RI ?10% (OR 1.769 CI95% 1.172-2.669). Conclusions- High frequency of RI altered was demonstrated in newborns with BPD and the comparison group without clinics signs of GERD. The chance of RI ?10% increased in 76.9% in each increase of 100 grams in the BW. The results showed that the prevalence of RI ?10% not is major in neonates with BPD. Asymptomatic newborns or infants with apnea of prematurity may present IR ?10%, so the diagnosis of GERD based on the results of esophageal pH monitoring and indication of any therapeutic modality needs to be careful until a definition of which are infants who need treatment / Doutorado / Saude da Criança e do Adolescente / Doutor em Saude da Criança e do Adolescente

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2017-06-09T15:51:35Z No. of bitstreams: 2 Tese - Fernanda Aparecida de Oliveira Peixoto - 2015.pdf: 1346302 bytes, checksum: 7ffcffc54a65cec4c0a8986361b2cfb2 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-06-09T15:51:55Z (GMT) No. of bitstreams: 2 Tese - Fernanda Aparecida de Oliveira Peixoto - 2015.pdf: 1346302 bytes, checksum: 7ffcffc54a65cec4c0a8986361b2cfb2 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-06-09T15:51:55Z (GMT). No. of bitstreams: 2 Tese - Fernanda Aparecida de Oliveira Peixoto - 2015.pdf: 1346302 bytes, checksum: 7ffcffc54a65cec4c0a8986361b2cfb2 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2015-08-07 / Despite the improvement in survival of premature infants, there was no progress in the incidence of bronchopulmonary dysplasia, especially in the last 20 years. Systemic corticosteroids, which has always been a therapeutic option, fell into disuse because of its adverse effects on the neurological development of premature infants and other routes of admistration have been researched for use of corticosteroids. Budesonide, which is an inhaled steroid, has been studied in an attempt to prevent bronchopulmonary dysplasia. The objectives of this study were to determine if the intratracheal instillation of budesonide with surfactant, improved lung performance, prevents chronic lung disease and reduces mortality in premature infants with minimal adverse effects. This is a clinical trial, blind and randomized 90 preterm infants who required prophylaxis or early rescue therapy with surfactant: 45 were randomized in the treated group (0.25 mg/kg of budesonide and 100 mg/kg surfactant) and 45 in the control group (100 mg/kg of surfactant). The evaluated final outcomes were mortality and bronchopulmonary dysplasia. Although the treatment group has shown better results than the control group, in both cases, mortality (10x15) and bronchopulmonary dysplasia at 36 weeks corrected gestational age (8/35 x 10/32), there was no significant statistical difference (p = 0.501 and p = 0.571). No clinically significant adverse events were observed in the study. The study concludes that, despite not having been demonstrated statistically significant difference in your results, we can not rule out the benefits of budesonide instilled into the trachea through the surfactant. Other randomized and multicenter studies should be encouraged. / Apesar da melhora na sobrevida dos recém-nascidos prematuros, não houve progresso em relação à incidência da displasia broncopulmonar, sobretudo nos últimos 20 anos. O corticoide sistêmico, que sempre foi uma opção terapêutica, entrou em desuso devido aos seus efeitos adversos no desenvolvimento neurológico dos prematuros. Outras vias têm sido pesquisadas para a utilização do corticoide. A budesonida, que é um esteroide de uso inalatório, tem sido estudada na tentativa de prevenir a displasia broncopulmonar. Os objetivos deste estudo foram determinar se a instilação intratraqueal de budesonida, por meio do surfactante, melhora o desempenho pulmonar, previne a doença pulmonar crônica e reduz a mortalidade em prematuros, com o mínimo de efeitos adversos possíveis. Trata-se de um ensaio clínico, cego e randomizado com 90 recém-nascidos prematuros que necessitaram de profilaxia ou de terapia de resgate precoce com surfactante: 45 foram randomizados no grupo tratado (0,25 mg/kg de budesonida e 100 mg/kg de surfactante) e 45 no grupo controle (100 mg/kg de surfactante). Os desfechos finais avaliados foram mortalidade e displasia broncopulmonar. Embora o grupo de tratamento tenha mostrado resultados melhores do que o grupo de controle, tanto para a mortalidade (10x15) quanto para displasia broncopulmonar avaliada com 36 semanas de idade gestacional corrigida (8/35 x 10/32), não houve diferença estatística significativa (p = 0,501 e p = 0,571). Nenhum evento adverso clinicamente significativo foi observado no estudo. O estudo conclui que, apesar de não ter sido demonstrado nenhuma diferença estatística significativa em seus resultados, não se pode descartar os benefícios da budesonida instilada na traqueia por meio do surfactante. Outros estudos randomizados e multicêntricos devem ser encorajados.

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by Lam Kuo. / Year shown on spine: 1997. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (leaves 107-121). / Acknowledgments / List of Abbreviations / Summary / List of Contents / List of Tables / List of Figures / Chapter Chapter 1 --- Introduction and the objectives of the study --- p.1-6 / Chapter Chapter 2 --- Overviews of Bronchopulmonary Dysplasia (BPD) and bronchodilator therapy -- a literature review --- p.7-29 / Chapter 2.1 --- Overview of Bronchopulmonary Dysplasia (BPD) --- p.7-9 / Chapter 2.2. --- Bronchodilator therapy --- p.10-18 / Chapter 2.2.1 --- Therapeutic value on infants with Bronchiolitis / Chapter 2.2.2. --- Therapeutic value on infants with Bronchopulmonary Dysplasia (BPD) / Chapter 2.3. --- "Three modes of aerosol delivery devices --jet nebuliser , ultrasonic nebuliser and metered dose inhaler" --- p.18-29 / Chapter 2.3.1. --- Jet nebuliser / Chapter 2.3.2. --- Ultrasonic nebuliser / Chapter 2.3.3. --- Metered dose inhaler / Chapter 2.3.4. --- Comparison of the therapeutic efficiency between jet nebuliser， ultrasonic nebuliser and Metered dose inhaler / Chapter 2.3.4.a. --- Comparison of particle size / Chapter 2.3.4.b. --- Comparison of aerosol deposition / Chapter 2.3.4.c. --- Comparison of pulmonary function / Chapter Chapter 3 --- Pulmonary function test in neonates --a literature review --- p.30-40 / Chapter 3.1. --- Overview of pulmonary function test in neonates --- p.30 / Chapter 3.2. --- Assessment of pulmonary function test in neonates --- p.31-40 / Chapter 3.2.1. --- Pulmonary mechanics / Chapter 3.2.1.a. --- Lung compliance / Chapter 3.2.1.b. --- Airway resistance / Chapter 3.2.1.c. --- Functional residual capacity (FRC) / Chapter Chapter 4 --- Subjects and methods --- p.41-48 / Chapter 4.1. --- Subjects --- p.41-42 / Chapter 4.2. --- Methods --- p.42-48 / Chapter 4.2.1. --- Delivery of Salbutamol aerosol / Chapter 4.2.1.1. --- Spontaneously breathing non-ventilated infants (group 1) / Chapter 4.2.1.2. --- Ventilator-dependent infants (group 2) / Chapter 4.2.2. --- Monitoring the clinical parameters / Chapter 4.2.3. --- Measurement of pulmonary function / Chapter 4.2.4. --- Statistics / Chapter Chapter 5 --- Results --- p.49-53 / Chapter 5.1. --- Clinical parameters --- p.50-51 / Chapter 5.2. --- Pulmonary function tests --- p.51-53 / Chapter Chapter 6 --- Discussion --- p.54-61 / Chapter 6.1. --- Non-ventilated group --- p.55-58 / Chapter 6.2. --- Ventilated group --- p.58-61 / Chapter Chapter 7 --- Conclusion --- p.62-63 / Tables and Figures / References

La dysplasie bronchopulmonaire (DBP) constitue la principale séquelle respiratoire de la prématurité. Elle est caractérisée par des altérations du développement alvéolaire et est définie cliniquement par la persistance d'une oxygénodépendance à 36 semaines d'âge corrigé. Malgré l'amélioration constante des soins en néonatologie, la DBP reste relativement fréquente chez les prématurés de moins de 1000g, et aucun traitement préventif ou curatif véritablement efficace n'existe à l'heure actuelle. Une susceptibilité génétique à la DBP a été démontrée il y quelques années. L'identification de gènes de susceptibilité permettrait non seulement de mieux comprendre la physiopathologie de cette maladie, mais également de dégager de nouvelles pistes thérapeutiques. Les études disponibles sont basées sur une approche gène candidat, le plus souvent sur un nombre limité de sujets, et aucune d'entre elles n'a pu être répliquée dans d'autres populations. Nous avons donc décidé de réaliser une étude d'association pan-génomique à la recherche de gènes de susceptiblité à la DBP.Cette étude multicentrique a permis la constitution prospective d'une base de données cliniques et biologiques et d'une banque d'ADN de nouveau-nés prématurés de moins de 28 SA. L'étape de screening pan-génomique a été réalisée par une stratégie de DNA pooling dans deux populations ethniques différentes, et la validation par génotypage individuel dans deux populations de réplication. Les gènes sélectionnés ont ensuite été étudiés au cours du développement pulmonaire chez le rat.L'ensemble de la démarche pan-génomique a permis d'identifier un gène majeur, commun à l'ensemble des populations étudiées: SPOCK2. Notre étude a également permis d'identifier MMP16 comme gène de susceptibilité à partir des premiers résultats du DNA pooling dans la population caucasienne. L'étude de ces deux gènes au cours du développement pulmonaire chez le rat nous oriente fortement vers un rôle au cours du développement alvéolaire, avec un pic d'expression au cours de l'alvéolisation et une altération de cette expression dans le modèle hyperoxie. De plus, SPOCK2 et MMP16 appartiennent à une voie de signalisation commune, ce point renforçant fortement la crédibilité du rôle de ces gènes dans la susceptibilité à la DBP. Le rôle exact de ces gènes dans l'alvéolisation et la DBP reste à déterminer ainsi que les conséquences fonctionnelles potentielles des polymorphismes identifiés. Parallèlement, la collecte de nouveaux échantillons d'ADN chez des anciens prématurés ainsi que la collaboration avec des équipes étrangères permettra de poursuivre les études d'association dans des populations de plus en plus importantes / RationaleBronchopulmonary dysplasia is the most common chronic respiratory disease in prematureinfants. Genetic factors might contribute to bronchopulmonary dysplasia susceptibility.ObjectivesTo identify genetic variants involved in bronchopulmonary dysplasia through a genome-wideassociation study.MethodsWe prospectively evaluated 418 premature neonates (gestational age below 28 weeks), ofwhom 22% developed bronchopulmonary dysplasia. Two discovery series were created, usinga DNA pooling strategy in neonates from Caucasian and African ancestry. Polymorphismsassociated with the disease were confirmed in an independent replication population. Geneswere then explored by fine mapping and associations were replicated in an external Finnishpopulation of 213 neonates. Validated genes expression patterns were studied in rat lung,following air or hyperoxia exposure.Measurements and Main ResultsSPOCK2 gene was identified by both discovery series. The most significant polymorphism(rs1245560, p=1.66x10-7) was confirmed by individual genotyping, and in the replicationpopulation (p=0.002). Fine mapping confirmed the association of rs1245560 withbronchopulmonary dysplasia in both Caucasian and African populations with adjusted oddsratios of 2.96 (95% CI [1.37-6.40]) and 4.87 [1.88-12.63] respectively. In Caucasian neonates,rs1049269 was also associated with the disease (OR=3.21 [1.51-6.82]). These associationswere replicated in the Finnish population. In newborn rat lungs, SPOCK2 mRNA levelsmarkedly increased during the alveolar stage of lung development. After rat exposure tohyperoxia, SPOCK2 expression increased relative to air-exposed controls

O presente estudo avaliou o sistema oculomotor medido por movimentos oculares em bebês com diagnóstico de Displasia Broncopulmonar (DBP). Bebês com idade gestacional 37 semanas, dependentes de oxigênio em concentrações acima de 21% por mais de 28 dias foram incluídos no grupo DBP, bebês nascidos a Termo (idade gestacional > 37 semanas), não internados foram incluídos no grupo nascido a termo e bebês prematuros (idade gestacional < 37 semanas), que permaneceram internados e que não fizeram uso de oxigênio por mais de 10 dias foram incluídos no grupo prematuro. Os bebês dos três grupos tinham exame oftalmológico de biomicroscopia e de fundo de olho com resultados normais. Foram excluídos do estudo, bebês em uso de oxigênio sob ventilação mecânica e/ou drogas vasoativas, com diagnóstico de hemorragia intracraniana, retinopatia da prematuridade e malformações motoras e/ou neurológicas congênitas ou adquiridas identificadas no exame neonatal ou durante a estadia no berçário. Todos os bebês realizaram uma única avaliação binocular. As avaliações foram realizadas com os bebês sentados confortavelmente e eram compostas pela avaliação de quatro movimentos oculares: sacadas (SAC), perseguição lenta (PL), reflexo vestíbulo-ocular (RVO) e nistagmo optocinéticos (NOC). Os movimentos oculares foram transcritos em variável categórica (presente ou ausente) e para análise estatística foram feitas comparações entre o grupo DBP, grupo nascido a termo e grupo prematuro (Teste Cochran Q), para garantir a confiabilidade dos resultados apresentados durante a avaliação, 28% da amostra foi avaliada por três observadores e um teste de aderência X2 foi utilizado para medir a confiabilidade entre os três observadores. Durante o estudo foram avaliados 109 bebês, 107 foram incluídos no estudo, dois bebês, com IG < 37 semanas, foram excluídos por usarem oxigênio por um tempo igual há 15 dias. Dos 107 bebês avaliados, 23 foram inclusos no grupo DBP, 47 no grupo nascido a termo e 37 no grupo prematuro. Os bebês do grupo DBP tiveram IG média de 32 semanas ± 3 semanas, APGAR 1° minuto 6 ± 1, 5° minuto 8 ± 2, 37 dias em oxigênio ± 10 dias, na quantidade média de 2 L/min ± 0,5 L/min. O peso de nascimento, idade gestacional, APGAR NO 1° e 5° minutos do grupo nascido a termo, DBP e Prematuro diferem significativamente entre si (Teste Kruskal-Wallis p = 0.0000, 0.0000, 0.0000, 0.0013 e 0.0001, respectivamente). O grupo nascido a termo apresentou maiores valores quando comparado ao grupo DBP e prematuro. Bebês com DBP manifestam ausência de três dos quatro tipos de movimentos oculares medidos quando comparado com o grupo nascido a termo e prematuro (Teste Q Cochran onde Q > 2 e p, < 0,05) / This study evaluated the oculomotor system measured by eye movements in infants diagnosed with bronchopulmonary dysplasia (BPD). Infants 37 weeks gestational age, oxygen-dependent at concentrations above 21% for more than 28 days were included in the BPD group, term infants (gestational age > 37 weeks), not hospitalized were included in term groups and preterm infants (gestational age < 37 weeks), who remained hospitalized and did not use oxygen for more than 10 days were included in the premature group. The three groups of babies had eye examination and biomicroscopy of the fundus with normal results. Excluded from the study, babies on oxygen in mechanical ventilation and/ or vasoactive drugs; with a diagnosis of intracranial hemorrhage, retinopathy of prematurity, motor and/or neurological congenital or acquired malformations identified in neonatal or during the stay in the nursery. All infants made a single binocular assessment. The evaluations were conducted with babies seated comfortably and were composed by the evaluation of four eye movements: saccades (SAC), slow pursuit (PL), vestibuloocular reflex (VOR) and optokinetic nystagmus (NOC). Eye movements were transcribed into a categorical variable (present or absent) and statistical analysis were made between BPD group, term group and premature group (Cochran Q test) to ensure reliable of the results presented during the evaluation, 28 % of the sample was evaluated by three observers and an adherence X2 test was used to measure the reliable between three observers. During the study, 109 infants were evaluated, 107 were included in the study, two infants with GA < 37 weeks, were excluded by using oxygen for a time equal to 15 days. Of the 107 infants evaluated, 23 were included in the BPD group, 47 in the term group and 37 in the premature group. Babies in the BPD group had GA of 32 weeks ± 3 weeks, APGAR 1st minute 6 ± 1, 5th minutes 8 ± 2, 37 days ± 10 days in oxygen, in the median amount of 2 L / min ± 0.5 L / min. Birth weight, gestational age, APGAR score at 1st and 5th minutes from the term group, DBP and Premature differ significantly (Kruskal-Wallis test p = 0.0000, 0.0000, 0.0013 and 0.0001, respectively). The term group had higher values when compared to the BPD and premature. Babies with BPD manifest absence of three of the four types of eye movements measured when compared with the term group and preterm (Cochran Q test where Q > 2 and p < 0.05)

INTRODUÇÃO: A lesão pulmonar da nova displasia broncopulmonar se caracteriza por uma diminuição da septação alveolar e do desenvolvimento vascular, ocorre um bloqueio no desenvolvimento pulmonar e consequentemente uma diminuição da alveolarização. A lesão pulmonar ocorre devido à associação de diversos fatores, incluindo a prematuridade, defesas antioxidantes inadequadas, e a ativação da resposta inflamatória. A exposição prolongada ao oxigênio também resulta em anormalidades na formação e na morfologia dos alvéolos, com redução tanto do volume pulmonar como da área de superfície interna alveolar. O objetivo do presente estudo foi comparar dois modelos de indução de lesão pulmonar através da exposição à hiperoxia prolongada em coelhos. MÉTODOS: Coelhas grávidas da raça New-Zealand-White foram sedadas para realização do parto cesáreo no 28º dia de gestação (termo = 31dias), coelhos prematuros foram expostos ao ar ambiente ou FiO295%. Outro grupo nasceu no 29º dia de gestação e foi exposto ao ar ambiente ou a uma FiO2=80%. Os animais foram mantidos em incubadora com controle de temperatura e alimentação e uma fórmula especial de leite similar ao leite de coelha por 11 dias. Desta forma, foram constituídos quatro grupos de estudo: Ar ambiente com 28 dias de gestação (Ar 28); exposição ao oxigênio (FiO2 95%) com 28 dias de gestação (O2 28); ar ambiente com 29 dias de gestação (Ar 29); exposição ao oxigênio (FiO2 = 80%) com 29 dias de gestação (O2 29). Após o sacrifício os pulmões foram fixados com 30 cmH2O de pressão transtraqueal. As lâminas do tecido pulmonar foram submetidas às seguintes colorações: hematoxilina e eosina para análise morfométrica; Weigert, resorcina-orceína modificado para a análise das fibras elásticas e Picrosirius para análise do colágeno. Foi realizada a contagem do Intercepto Linear Médio (Lm), determinada a Área de Superfície Interna (ISA), o número de alvéolos por campo microscópico, o espessamento septal e a proporção de fibras elásticas e colágenas. Análise Estatística: As variáveis contínuas foram analisadas por ANOVA One Way e a análise da sobrevida foi realizada através de uma curva de Kaplan-Meyer. O nível de significância adotado foi de 0.05. RESULTADOS: A sobrevida nos grupos de 29 dias foi melhor quando comparados com o grupo 28 dias. A hiperoxia bloqueou o desenvolvimento normal do pulmão, demonstrado por um aumento no Lm, uma diminuição significativa na ISA, uma diminuição no número de alvéolos, um aumento na espessura do septo interalveolar e também um aumento na proporção de fibras elásticas e uma diminuição na proporção de fibras colágenas nos dois grupos de animais expostos ao oxigênio em relação aos grupos que permaneceram em ar ambiente. CONCLUSÕES: Em coelhos prematuros o uso de uma concentração de oxigênio menor e um dia a mais de gestação reduziu a taxa de mortalidade mantendo os achados histopatológicos compatíveis aos da displasia broncopulmonar em humanos / INTRODUCTION: The lung injury of the \"new\" bronchopulmonary dysplasia is characterized by a decrease in alveolar septation and vascular development, resulting in a pulmonary arrest and a decrease in alveolarization. Lung damage occurs due to the association of many factors, including prematurity, inadequate antioxidant defenses and activation of the inflammatory response. Prolonged exposure to oxygen also results in abnormalities in the formation and morphology of the alveoli, with reduced lung volume and alveolar internal surface area. The aim of this study was to compare two models of lung injury induced by prolonged exposure to hyperoxia in rabbits. METHODS: New Zealand-White pregnant rabbits were sedated to perform a cesarean section on day 28 of gestation (term = 31days), premature rabbits were exposed to room air or FiO295%. Another group of animals was born at day 29 of gestation and was exposed to room air or FiO2=80%. The animals were kept in an incubator with temperature control and fed with a special milk formula similar to rabbit milk for 11 days. Four study groups were formed: Room air and 28 days of gestation (Air 28); exposure to oxygen (FiO295%) and 28 days of gestation (O2 28); room air and 29 days of gestation (Air 29 ); exposure to oxygen (FiO2=80%) and 29 days of gestation (O2 29). For microscopic evaluation, after sacrifice the lungs were fixed in situ at a constant inflation pressure of 30 cm H20. Lung slices were processed for hematoxylin-eosin staining - for morphometric analysis, Weigert\'s resorcin-orcein modified for the analysis of elastic fibers and Picrosirius - for analysis of collagen. The mean linear intercept (Lm), the internal surface area (ISA), the number of alveoli, the septal thickness and the proportion of elastic and collagen fibers were quantified. Statistical analysis was by One Way ANOVA for continuous variables, survival analysis was performed using a Kaplan-Meyer plot. The level of significance was 0.05. RESULTS: Survival in both 29 days groups was better when compared with 28 days groups. Hyperoxia impaired the normal development of the lung, demonstrated by an increase in Lm, a significant decrease in ISA, a decrease in the alveoli number, an increase in the septal thickness and an increase in the proportion of fibers elastic and a decrease in the proportion of collagen fibers in oxygen exposed animals. CONCLUSIONS: In premature rabbits using a lower concentration of oxygen and one more day of gestation reduced the mortality rate maintaining the histopathological findings similar to bronchopulmonary dysplasia in humans