Introduction. Pertussis is a highly contagious disease caused by Bordetella pertussis. It poses a high morbidity and mortality rate, especially among infants younger than 6 months old. In Argentina, pertussis incidence and mortality have increased over the past three decades. Objective. To establish Bordetella pertussis antibody titers among pregnant women in their third trimester and among newborn infants, as measured in cord blood. Methods. This was an observational, crosssectional study. The study started in 2011; at that time, pertussis vaccination was not mandatory for pregnant women as per the national immunization schedule, only optional. Maternal antibodies were measured in the last trimester of pregnancy for women and in cord blood for newborn infants. Antibody titers were determined using Abcam's anti-Bordetella pertussis toxin (PT) IgG in vitro ELISA kit. The X2 test was used to compare prevalence rates. Results. The study included 111 mother-newborn infant dyads; 35 infants from unvaccinated mothers (before the introduction of the vaccine) and 76 from vaccinated mothers. Positive IgG antibodies were found in 92% (70/76) of infants born from vaccinated mothers whereas 100% (35/35) of infants born from unvaccinated mothers had negative results for antibodies; p < 0.001. Conclusion. In the vaccinated population of this study, 92% of infants had positive IgG antibodies. This study supports the need for maternal immunization against Bordetella pertussis to provide protection to newborn infants.

Introducción. La tos convulsa es una enfermedad altamente contagiosa causada por Bordetella pertussis. Tiene una alta tasa de morbilidad y mortalidad, especialmente, en los lactantes menores de seis meses de edad. En la Argentina, la incidencia y la mortalidad se han encontrado en aumento en las últimas 3 décadas. Objetivo. Determinar anticuerpos contra Bordetella pertussis en las mujeres embarazadas en el tercer trimestre de la gestación y en el recién nacido, medidos en la sangre del cordón. Métodos. Se disenó un estudio observacional, transversal. El estudio se inició en 2011 cuando la vacunación contra pertussis en la embarazada no estaba incluida en el Calendario Nacional de Vacunación y era opcional. Los anticuerpos se midieron en las madres en el tercer trimestre del embarazo y en la sangre del cordón umbilical al nacer. Las determinaciones de anticuerpos se realizaron con el kit de ELISA humano para IgG toxina pertussis ABCAMR. Se utilizó la prueba de chi² para comparar la prevalencia. Resultados. Se incluyó a 111 madres y a sus bebés, 35 hijos de madres no vacunadas (antes de la implementación de la vacuna en embarazadas) y 76 hijos de madres vacunadas. Los bebés de madres vacunadas presentaron anticuerpos IgG positivos en el 92% (70/76), mientras que los bebés de madres no vacunadas fueron negativos para anticuerpos IgG en el 100% (35/35) con una p < 0,001. Conclusión. En la población de vacunadas del estudio, se observó que sus hijos presentaron anticuerpos IgG positivos en el 92%. Este estudio apoya la necesidad de la inmunización materna contra Bordetella pertussis para proteger al recién nacido.

OBJETIVOS: Desenvolver um modelo de predição para o tempo de permanência hospitalar (TPH) em lactentes de muito baixo peso ao nascer (MBPN) e comparar esse resultado entre 20 centros de uma rede neonatal, visto que o TPH é utilizado como uma medida da qualidade da assistência em lactentes de MBPN. MÉTODOS: Utilizamos dados coletados prospectivamente de 7.599 lactentes com peso ao nascer entre 500 e 1.500 g no período entre os anos de 2001 a 2008. O modelo de regressão de Cox foi empregado para desenvolver dois modelos de predição: um modelo prévio com dados do nascimento e outro posterior, que acrescenta morbidades relevantes dos primeiros 30 dias de vida. RESULTADOS: A mediana do TPH estimado e ajustado a partir do nascimento foi de 59 dias; 28 dias depois do tempo de sobrevida de 30 dias. Houve uma alta correlação entre os modelos (r = 0,92). O TPH esperado e o TPH observado variaram bastante entre os centros, mesmo depois de correção para as morbidades relevantes após 30 dias. O TPH mediano (variação: 45-70 dias) e a idade concepcional na alta hospitalar (variação: 36,4-39,9 semanas) refletem uma variabilidade alta entre centros. CONCLUSÃO: Um modelo simples, com fatores apresentados no nascimento, pode predizer o TPH de um lactente de MBPN em uma rede neonatal. Observou-se uma variabilidade nos TPHs considerável entre unidades de terapia intensiva neonatal. Especulamos que os resultados sejam provenientes das diferenças entre as práticas dos centros.

OBJECTIVES: To develop a prediction model for hospital length of stay (LOS) in very low birth weight (VLBW) infants and to compare this outcome among 20 centers within a neonatal network. METHODS: Data from 7,599 infants with birth weights of 500-1,500 g born between the years 2001-2008 were prospectively collected. The Cox regression model was employed to develop two prediction models: an early model based upon variables present at birth, and a late one that adds relevant morbidities for the first 30 days of life. RESULTS: Median adjusted estimated LOS from birth was 59 days ‒ 28 days after 30-day point of survival. There was a high correlation between models (r = 0.92). Expected/observed LOS varied widely among centers, even after correction for relevant morbidity after 30 days. Median observed LOS (range: 45-70 days), and postmenstrual age at discharge (range: 36.4-39.9 weeks) reflect high inter-center variability. CONCLUSION: A simple model, with factors present at birth, can predict a VLBW infant's LOS in a neonatal network. Significant variability in LOS was observed among neonatal intensive care units. We speculate that the results originate in differences in inter-center practices.

Introduction. Although the provision of effective assisted ventilation is the most effective intervention in delivery room resuscitation of depressed newborn infants, there is still limited evidence about which is the optimal device to deliver positive pressure ventilation (PPV). Objective. To compare the accuracy of pressures and ventilation rate (VR) delivered to a neonatal simulator with three devices: 240 ml and 450 ml self-infating bags (SIB) and a T-piece resuscitator, and to evaluate the variability in terms of providers' experience. Material and methods. 76 health care providers divided in two groups according to experience were asked to provide positive pressure ventilation to a neonatal simulator through a facial mask or an endotracheal tube with three ventilating devices: a T-piece resuscitator, a 240 ml and a 450 ml self-infating bags. Participants used each combination of device and interface randomly on 2 consecutive occasions. Mean and maximum PIP and respiratory rate were recorded. Statistical analyses were performed using two-factor analysis of variance for repeated measures. Result. SIB 240 and 450 were similar in the mean target peak inspiratory pressure (PIP) but both were significantly different (p < 0.001) from T-piece, although all values were close to the target. Mean VR was over the target for all the devices (p < 0.001). The highest difference found was 7 ± 1.7 breaths/minute with the 240 ml bag when compared with the T-piece using a mask. Experienced operators were closer than novice operators to target VR, regardless of the device or interface. Conclusion. The accuracy for the devices was comparable in the variables measured regardless operator´s experience. Overall, the T-piece provided lower PIP while both SIB, higher than the target. The VR was over the target for all the devices. Both SIB and novice participants were associated with higher VR. The intraoperator consistency was comparable in the variables measured with all devices.

Introducción. Administrar ventilación asistida adecuada es la intervención más eficaz durante la reanimación de los recién nacidos en sala de partos. La evidencia sobre cuál es el dispositivo óptimo para suministrar ventilación con presión positiva (VPP) luego del nacimiento es aún limitada. Objetivo. Comparar la precisión en la administración de presión positiva y frecuencia respiratoria en un modelo de reanimación neonatal, con bolsas autoinflables (BAI) de 240 ml y 450 ml y un reanimador con pieza en T y evaluar la variabilidad según la experiencia del operador. Población y métodos. 76 profesionales divididos en dos grupos, de acuerdo a su experiencia, realizaron VPP a un simulador neonatal empleando los tres dispositivos de ventilación, con máscara facial y tubo endotraqueal. Utilizaron aleatoriamente cada combinación de dispositivo y la interfaz en dos oportunidades consecutivas. Se realizó análisis de varianza a dos factores para mediciones repetidas. Resultados. Las BAI 240 y 450 fueron similares en la media de la presión inspiratoria máxima (PIM), pero ambas fueron significativamente diferentes (p < 0,001) con respecto al reanimador con pieza en T, aunque los valores se acercaron a lo solicitado. La frecuencia respiratoria media sobrepasó la indicada con todos los dispositivos (p < 0,001). Los operadores experimentados, independientemente del dispositivo y de la interfaz utilizados, estuvieron más cerca que los principiantes de la frecuencia respiratoria solicitada. Conclusión. Tanto la pieza en T como las BAI administraron PIM cercanas a las indicadas, independientemente de la experiencia del operador, y con las bolsas se observaron valores superiores. Las BAI y los operadores principiantes se asociaron con una mayor FR. La consistencia intraoperador fue equiparable en las variables medidas con todos los dispositivos.

Background Despite the sustained progress in neonatal cardiovascular surgery in the last 30 years, premature newborns with congenital heart defects pose an additional challenge to the multidisciplinary team taking part in the intervention due to the frequent association with comorbidities and low weight. Unlike historical strategies, and imitating successful approaches reported in the last decade, we have been performing corrective surgeries in symptomatic patients since 2007, irrespective of weight and age, in order to improve their cardiac status and thus overcome the associated comorbidities. Objective To report the initial experience in cardiovascular surgery (CVC) with cardiopulmonary bypass (CPB) in newborns weighing less than 2500 grams. Material and Methods From May 2007 to May 2009, 11 newborns underwent CBP surgery. Mean age was 24 days (4 to 90 days), gestational age was 34 weeks (32 to 37) and mean weight was 2.27 kg (1.7 to 2.5). Before the intervention, 7 patients were under mechanical ventilation (MV) and 9 were receiving inotropic drugs. The diagnoses were ventricular septal defect (n = 4, one with severe coarctation of the aorta), total anomalous pulmonary venous drainage (n = 2), transposition of the great arteries (n = 2), pulmonary atresia with intact ventricular septum (n = 1), pulmonary atresia with ventricular septal defect (n = 1) and hypoplastic left heart syndrome (n = 1). Patients underwent either deep hypothermic circulatory arrest with a rectal temperature of 18 °C with intermittent flow perfusion (n = 8) or continuous flow perfusion with a rectal temperature of 28 °C (n = 3). Biventricular correction was performed in 10 patients and 1 patient underwent the Norwood procedure. Results The sternotomy remained opened in 8 patients; mean time to closure was 3.5 days (3 to 5). Three patients with unremitting bleeding required therapy with factor VII. Mean duration of MV was 7.5 days (2 to 20). Bleeding (n = 5), sepsis (n = 2) and chylothorax (n = 1) were the most frequent complications. There were no early deaths and only one patient died during late follow-up of sepsis due to Candida albicans. Nine survivors are in good general condition free from symptoms and one patient presents compensated heart failure. Conclusions The initial outcomes of cardiovascular surgery with CPB in newborns are promising, yet the initial morbidity is high.

Introducción No obstante el progreso sostenido en cirugía cardiovascular neonatal en los últimos 30 años, los recién nacidos prematuros con cardiopatías congénitas presentan un desafío adicional al equipo multidisciplinario interviniente debido a la frecuente asociación de comorbilidades y bajo peso. A diferencia de las estrategias históricas diferidas de diferir la cirugía, desde 2007 llevamos a cabo cirugías correctoras sin importar el peso ni la edad en pacientes sintomáticos con el propósito de mejorar su estado cardíaco para que pudieran superar las comorbilidades asociadas. Objetivo Comunicar la experiencia inicial en cirugía cardiovascular (CCV) con circulación extracorpórea (CEC) en neonatos de menos de 2.500 gramos. Material y métodos De mayo de 2007 a mayo de 2009, 11 neonatos fueron intervenidos con CEC. La edad media fue de 24 días (4 a 90 días), la edad gestacional media fue de 34 semanas (32 a 37) y el peso medio, de 2,27 kg (1,7 a 2,5). Previo a la intervención, siete pacientes estaban con asistencia respiratoria mecánica (ARM) y nueve con inotrópicos. Los diagnósticos fueron comunicación interventricular (n = 4, uno con coartación de la aorta grave), anomalía total del retorno venoso pulmonar (n = 2), transposición de grandes arterias (n = 2), atresia pulmonar con septum íntegro (n = 1), atresia pulmonar con comunicación interventricular (n = 1) e hipoplasia del ventrículo izquierdo (n = 1). Se utilizó hipotermia profunda a 18 °C de temperatura rectal con paro circulatorio total intermitente (n = 8) o flujo completo a 28 °C de temperatura rectal (n = 3). En 10 pacientes se realizó cirugía correctora biventricular y en uno se efectuó cirugía de Norwood. Resultados En 8 pacientes se dejó el esternón abierto, con un tiempo medio al cierre de 3,5 días (3 a 5). Tres pacientes requirieron factor VII por presentar sangrado incoercible. El tiempo medio de ARM fue de 7,5 días (2 a 20). Las complicaciones más comunes fueron sangrado (n = 5), sepsis (n = 2) y quilotórax (n = 1). No hubo mortalidad inicial y sólo un paciente falleció alejadamente debido a sepsis por Candida albicans. Nueve sobrevivientes se encuentran en buen estado general libres de síntomas y uno con insuficiencia cardíaca compensada. Conclusiones La CCV con CEC en neonatos de bajo peso presenta resultados iniciales muy promisorios, pero con una morbilidad inicial significativa.

OBJETIVO: Determinar a incidência de displasia broncopulmonar, os fatores de risco e a utilização de recursos em uma ampla população sul-americana de recém-nascidos de muito baixo peso ao nascer MÉTODOS: Dados prospectivamente registrados de crianças com peso ao nascer entre 500 a 1.500 g, nascidas em 16 centros neonatais pertencendo à rede NEOCOSUR entre 10/2000 a 12/2003. A análise multivariada de Poisson com variância robusta foi utilizada para determinar os fatores de risco relativo e intervalo de confiança de 95% que afetam o risco de apresentação de displasia broncopulmonar RESULTADOS: Foram analisados 1.825 recém-nascidos de muito baixo peso ao nascer. As médias de peso ao nascer e a idade gestacional foram de 1.085±279g e 29±3 semanas, respectivamente. A incidência de displasia broncopulmonar foi de 24,4%, e a sobrevida sem displasia broncopulmonar aumentou quanto maior foi a idade gestacional. Maior peso ao nascer, maior idade gestacional e sexo feminino estiveram associados a um menor risco de displasia broncopulmonar. Aumentaram o risco de displasia broncopulmonar: ventilação mecânica, necessidade de surfactante, escape aéreo, persistência do canal arterial, sepse tardia e enterocolite necrotizante. As crianças com displasia broncopulmonar requerem um maior tempo hospitalização (91±27 versus 51±19), de ventilação mecânica (19±20 versus 4±7) e de oxigenioterapia (72±30 versus 8±14). CONCLUSÕES: A incidência de displasia broncopulmonar foi de 24,4% em uma ampla população sul-americana e se relaciona com uma maior utilização de recursos. Os fatores de risco associados à displasia broncopulmonar encontrados nesse estudo foram: ventilação mecânica, necessidade de surfactante, escape aéreo, persistência do canal arterial, sepse tardia e enterocolite necrotizante. As informações contidas neste estudo podem ser úteis para o delineamento de estratégias perinatais de prevenção da morbidade.

OBJECTIVE: To determine the incidence of bronchopulmonary dysplasia, its risk factors and resource utilization in a large South American population of very low birth weight infants. METHODS: Data were prospectively collected from infants weighing 500 to 1,500 g born at 16 NEOCOSUR Network centers from 10/2000 through 12/2003. Multivariate relative risk and 95% confidence intervals were estimated by Poisson regression with robust error variance to find factors that affected the risk of bronchopulmonary dysplasia. RESULTS: 1,825 very low birth weight infant survivors were analyzed. Mean birth weight and gestational age were 1085+279 g and 29+3 weeks respectively. Bronchopulmonary dysplasia incidence averaged 24.4% and survival without bronchopulmonary dysplasia augmented with increasing gestational age. Higher birth weight and gestational age and a female gender all decreased the risk for bronchopulmonary dysplasia. Factors that independently increased that risk were surfactant requirement, mechanical ventilation, air leak, patent ductus arteriosus, late onset sepsis and necrotizing enterocolitis. Bronchopulmonary dysplasia infants had more days of hospitalization (91±27 vs. 51±19), on mechanical ventilation (19±20 vs. 4±7) and oxygen therapy (72±30 vs. 8±14) in comparison with non BPD infants. CONCLUSIONS: Bronchopulmonary dysplasia incidence was 24.4% in a large South American population and is related to greater resource utilization. Risk factors for bronchopulmonary dysplasia in this study were: surfactant requirement, mechanical ventilation, air leak, patent ductus arteriosus, late onset sepsis and necrotizing enterocolitis. These studies may provide information useful to the design of effective preventive perinatal strategies.

Introduction. During medical visits to San Antonio de los Cobres, Salta, we noticed an increased rate of sudden unexpected postneonatal infant deaths, an average rate of 13 cases per thousand per annum between 1996 and 2001, with no postmortem studies. Taking into account that altitude is a risk factor for sudden infant death syndrome, and that at least 20% of sudden unexpected death of infants may be attributed to this syndrome, we considered describing the respiratory events during sleep of healthy infants from 1 to 6 months of age, who were native residents at this altitude, in relation to chronic exposure to hypobaric hypoxia. Population, materials and methods. Study design: cross sectional, descriptive and observational study including 12 infants recruited from the local urban population, studied with polysomnographic and pulse oximetry recordings at an altitude of 3,775 m above sea level. Inclusion criteria: children between the ages of 1 and 6 months, native and stable residents in the area. Exclusion criteria: gestational age below 36 weeks, clinically evident malnutrition, fever, recent history of upper or low respiratory tract infections, neurological disease, craniofacial malformations and congenital cardiopathies. Statistical analysis: anthropometric data were expressed as medians and ranges, and events occurring during sleep, as means ± SD and ranges. Results. There were occasional significant decreases in SaO2 during sleep, as well as associated to central or obstructive apneas and periodic breathing in all infants, with a minimum average of 67%. We found no changes in cardiac frequency in polysomnographic records during maximal hypoxemic events. Conclusion. All the studies differed from normal standards for children at sea level. There was an increased number of arousals compared to normal values, but not in the magnitude that might be expected in subjects with chronic hypobaric hypoxia when compared with normal sea level values. We found poor variability in the cardiac autonomic response to the marked hypoxemic events during sleep.

Introducción. Durante una visita médica a San Antonio de los Cobres, Salta, hallamos que los datos de mortalidad infantil en el área, mostraban una incidencia elevada de muerte inesperada del lactante posneonatal, con un promedio de 13 casos por mil por año entre 1996 y el 2001, sin estudios diagnósticos posmortem. Debido a que la altura es un factor de riesgo para el síndrome de muerte súbita del lactante y que por lo menos el 20% de los casos de muerte inesperada se pueden atribuir a éste, nos propusimos evaluar los eventos respiratorios durante el sueño en lactantes nativos y residentes, en relación a su exposición crónica a hipoxia hipobárica. Población, materiales y métodos. Diseño: Estudio de corte transversal, descriptivo y observacional de los eventos respiratorios durante el sueño a una altura de 3.775 m sobre el nivel del mar, de 12 lactantes sanos, reclutados en forma voluntaria en la población urbana del lugar, que constituyeron una muestra de tipo no probabilística, por medio de estudios poligráficos de sueño y oximetría de pulso. Criterios de inclusión: edad entre 1 y 6 meses, nativos y residentes estables. Criterios de exclusión: edad gestacional menor de 36 semanas, desnutrición clínica, fiebre, antecedente de infecciones respiratorias altas y bajas en las 4 últimas semanas, enfermedades neurológicas, malformaciones craneofaciales y cardiopatías congénitas. Análisis estadístico: Los datos antropométricos se expresaron en medianas, rangos y los eventos duarnte el sueño como media ± DE y rangos. Resultados. En todos los lactantes hubo descensos significativos de la SaO2 durante el sueño, tanto en forma espontánea como durante los eventos de apneas centrales, obstructivas y de respiración periódica, hasta valores promedio de 67%. No observamos cambios en la frecuencia cardíaca durante los episodios de máxima hipoxemia respecto de los valores en sueño en el trazado polisomnográfico. Conclusión. Todos los estudios fueron diferentes a los estándares de sueño en lactantes a nivel del mar. Hubo un aumento en el número de despertares respecto del considerado normal en el llano, pero no en la magnitud que hubiera sido esperable en pacientes con hipoxia hipobárica crónica. Encontramos una escasa variabilidad en la respuesta autonómica cardíaca en los episodios de mayor hipoxemia durante el sueño.