Scielo RSS <![CDATA[Revista chilena de pediatría]]> http://www.scielo.cl/rss.php?pid=0370-410620000005&lang=es vol. 71 num. 5 lang. es <![CDATA[SciELO Logo]]> http://www.scielo.cl/img/en/fbpelogp.gif http://www.scielo.cl <![CDATA[Atención pediátrica y sistemas de salud en Chile]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0370-41062000000500001&lng=es&nrm=iso&tlng=es <![CDATA[Tratamiento farmacológico de la hipertensión arterial en pediatría]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0370-41062000000500002&lng=es&nrm=iso&tlng=es Existe un gran número de drogas disponibles en el mercado para el tratamiento de la hipertensión arterial. Nuevos fármacos se introducen, cuya efectividad y toxicidad solo han sido estudiadas en adultos, desconociéndose la eficacia, el margen de seguridad y su efecto en el crecimiento y desarrollo infantil. La mayoría de las hipertensiones en pediatría son secundarias a causas renales. La elección del tratamiento va a depender de la etiología, del grado de hipertensión y del compromiso orgánico, como de la experiencia del médico. Este artículo esquematiza paso a paso el tratamiento habitual de la hipertensión en niños, además del manejo de casos especiales como son las emergencias hipertensivas que requieren hospitalización en las unidades de tratamiento intensivo, la hipertensión del recién nacido que se está diagnosticando cada vez con mayor frecuencia y la hipertensión en el insuficiente renal crónico que requiere ajuste de dosis en relación al grado de función renal y que con un control adecuado puede evitar o retardar el deterioro de dicha función<hr/>There are a great number of drugs available in the market for the treatment of arterial hypertension. New drugs whose effectiveness and toxicity are studied only in adults, are introduced, and so their efficacy, safety and effect on growth and development in children are not known. Hypertension in paedriatrics is usually due to renal causes. Choice of treatment will depend on the etiology, degree of hypertension and organ involvement as well as the physician´s experience. This article outlines step by step the usual treatment of hypertension in children and some special cases, such as hypertensive emergencies requiring admission to an ITU as well as newborn hypertension, which is being diagnosed with increasing frequency, and hypertension in chronic renal failure that require careful dose adjustments depending on renal function and in which careful management can prevent or retard further renal deterioration <![CDATA[Enterocolitis necrotizante: Experiencia de 15 años]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0370-41062000000500003&lng=es&nrm=iso&tlng=es El objetivo fue determinar las características clínicas, exámenes de laboratorio, radiografía de abdomen, evolución, tratamiento y sobrevida de los RN con ECN. Se analizaron las historias clínicas de 157 RN que desarrollaron ECN en un período de 15 años. En cada RN se evaluaron parámetros biomédicos, manifestaciones clínicas, exámenes complementarios, tratamiento efectuado y sobrevida. La incidencia de ECN fue de 1,8 por 1 000 RN vivos, siendo 85,4% (134/157) de pretérmino. La edad promedio de inicio de la ECN en los RN de pretérmino fue de 12,1 días y de 4,4 días en los RN de término. Las manifestaciones clínicas más frecuentes fueron: distensión abdominal en el 94,3%, residuo gástrico patológico en el 77,7% y sangre en deposiciones en el 36,9%. La radiografía de abdomen reveló dilatación asimétrica de asas intestinales en el 63%, neumatosis en el 45,9% y neumoperitoneo en el 14,6%. El tratamiento fue médico en el 62,4% y además quirúrgico en el 37,6%. La sobrevida fue de 60,5%. Se concluye que la ECN afecta principalmente a RN prematuros, cuyo inicio se presenta habitualmente a fines de la segunda semana de vida, en relación posiblemente a infección de predominio bacteriano<hr/>The objective of this study was to determine the clinical features, laboratory examinations, abdominal x-rays, evolution, treatment and survival rate of neonates with necrotising enterocolitis (NEC). The clinical histories of 157 neonates who developed NEC over a period of 15 years were reviewed. The biochemical parameters, clinical signs, examinations, treatment and survival rates were evaluated. The incidence was 1.8/1000 living neonates, 85.4% (n = 134) were premature. The average onset of NEC occurred at 12.1 days in preterms and 4.4 days in fullterms. The most frequent clinical signs were: abdominal distension 94.3%, pathological gastric residue 77.7%, blood in the stools 36.9%. In 63% abdominal x-rays revealed an asymmetrical swelling of intestinal loops, in 45.9% pneumatosis and in 14.6% puemoperitoneum. Treatment was medical in 62.4%, surgical in 37.6%. The survival rate was 60.5%. We conclude that NEC affects predominantly preterms, typically occurring by the end of the second week of life, possibly due to a bacterial infection <![CDATA[Enteroparasitosis en lactantes de un centro universitario privado de salud en Santiago de Chile]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0370-41062000000500004&lng=es&nrm=iso&tlng=es Objetivos: Determinar la frecuencia y tipo de enteroparásitos en exámenes coproparasitológicos tomados a lactantes. Comparar en un subgrupo de lactantes con y sin enteroparásitos, variables clínico-epidemiológicas. Pacientes y métodos: estudio retrospectivo descriptivo realizado en el total de 3 127 exámenes coproparasitológicos procesados en la Pontificia Universidad Católica de Chile (1994-1998), determinándose la frecuencia y especies parasitarias. Comparación de resultados entre grupos de lactantes con exámenes coproparasitológicos positivos y negativos respecto a motivo de solicitud del examen y diagnóstico nutricional. Resultados: Ciento sesenta y siete (5,3%) de los exámenes fueron positivos, encontrándose solo protozoos, principalmente G. lamblia. En lactantes con examen coproparasitológico positivo el motivo de solicitud más frecuente fue síndrome diarreico agudo y disentérico, de los cuales el 84,1% eran eutróficos y 4,5% desnutridos. En lactantes con examen coproparasitológico negativo la solicitud de examen se debió a mal incremento ponderal y desnutrición, encontrándose el 68,9% eutróficos y 24,4% desnutridos. Conclusiones: Se encontró presencia de enteroparásitos en los exámenes coproparasitológicos realizados a lactantes (en estos, destaca la ausencia de helmintos). La presencia de protozoos patógenos se asoció con deposiciones diarreicas y no se observó asociación con desnutrición o mal incremento ponderal<hr/>Objectives: To evaluate the intestinal parasitic infection frequency in coproparasitological samples in infants. To compare clinical-epidemiological variables among infants with/without parasitic infection. Subjects and Methods: a descriptive retrospective study was performed in 3,127 coproparasitological samples processed at Pontificia Universidad Católica de Chile (1994-1998) determining frequency and parasitic species. Results: 167 (5.3%) showed parasitic infection, only protozoan, mainly G. lamblia. The most frequent reason for requesting the coproparasitological exam in infants with parasitic infection was diarrhea. Also 84.1% of the infected children were well-nourished and 4.5% with malnutrition. The most frequent reason for requesting the exam in infants without intestinal parasitic infection was failure to thrive and malnutrition. In this group, 68.9% were well-nourished and 24.4% with malnutrition. Conclusions: Presence of enteric protozoan was found in the coproparasitological exams performed in infants (absence of helminths highlights as an important finding). The presence of pathogens protozoan was mainly associated with diarrhea and it was not a major factor related to malnutrition and failure to thrive <![CDATA[Análisis de la mortalidad infantil y factores condicionantes: Chile 1998]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0370-41062000000500005&lng=es&nrm=iso&tlng=es Se presenta el análisis de la mortalidad infantil chilena reciente, realizado a partir de los datos de INE, OMS y CELADE. La tendencia declinante ha llevado los valores a cifras de 10,3 por 1 000 nacidos vivos, que coloca a Chile entre los 3 países de menor mortalidad en Latinoamérica, con una reducción a la cuarta parte en los últimos 20 años. Más de la mitad de las muertes ocurren en las 4 primeras semanas. Dos tercios de la mortalidad infantil se produce por problemas neonatales y anomalías congénitas; otras causas de importancia son las enfermedades respiratorias, traumatismos y afecciones infecciosas trasmisibles. La variación del riesgo en las regiones chilenas oscila entre 8,9 y 14,2, advirtiéndose descenso en todas las regiones: No se encuentra correlación con la disponibilidad de médicos y camas hospitalarias, como tampoco con el ingreso mensual medio de las regiones. El análisis de los datos muestra el significado de la elevada paridad y de la edad avanzada de la madre y la condición de baja escolaridad. Menor significado tiene el sitio de residencia, la condición de legitimidad o la actividad económica de la madre. Cuando el peso de nacimiento es inferior a 1 500 g, el riesgo es 16 veces mayor que en niños de peso normal<hr/>Recent trends and features of infant mortality in Chile are analysed in this paper. Basic information from the Chilean National Institute of Statistics, W.H.O. and the Latin American Centre of Demography were used for the analysis. The present rate of 10.3 deaths per 1000 births is one of the three lowest in Latin America and the downward trend has reduced to a quarter of that observed 20 years ago. More than half of the deaths are due to neonatal and congenital problems. Other important causes are respiratory diseases, accidents and communicable diseases. Infant mortality rates in the Chilean regions varies from 8.9 to 14.2. No significant correlation was found between regional figures and availability of physicians, hospital beds or income levels. Data analysis did confirm the significance of high parity, older age and low education level of the mother. Less significance was noticed for rural life, the condition of illegitimacy or the condition of working mother. Low birth weight children had a risk 16 times greater than babies with a normal birth weight <![CDATA[Transfusión de glóbulos rojos en recién nacidos de muy bajo peso (RNMBP) Hospital Clínico Regional de Valdivia]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0370-41062000000500006&lng=es&nrm=iso&tlng=es Los RNMBP constituyen un grupo expuesto a recibir numerosas transfusiones de glóbulos rojos desplasmatizados (tr GRD). Objetivos: Para conocer la incidencia de tr GRD, los factores asociados a requerimiento transfusional y el número de donantes por receptor, se revisaron las fichas clínicas de todos los RNMBPN (n = 66), egresados vivos de Neonatología, Hospital Clínico Regional de Valdivia, entre junio 1995 y mayo 1997. Se consideraron características propias del grupo en estudio, patología concomitante, número de tr GRD y días de hospitalización. Los factores de riesgo asociados a mayor requerimiento de tr GRD se determinaron mediante odds ratio (OR). El 89,4% recibió 1 o más tr GRD; la media de transfusiones fue 4,1 ± 3,9, con un rango de 1-17 tr GRD. Las características del grupo asociadas a mayor número de tr GRD fueron: peso de nacimiento con OR = 10,0 para el grupo de peso < 1 000 g; edad gestacional con OR = 7,9 para el grupo < 29 semanas y OR = 5,4 para los AEG. La patología asociada estuvo representada por: bronconeumonía OR = 46,5, hemorragias OR 25,0 y displasia broncopulmonar OR = 16,4. Los receptores de tr GRD estuvieron expuestos a igual número de transfusiones y donantes. Conclusiones: Se confirma una alta frecuencia de requerimientos transfusionales de GRD en RNMBPN, especialmente en los menores de 1 000 g de peso al nacer, y una edad gestacional menor a 29 semanas. La patología que mostró una mayor asociación con requerimientos transfusionales fue la bronconeumonía seguida por las hemorragias y la displasia broncopulmonar<hr/>VLBW babies form a group at risk to receive red cell transfusions (RCT). To evaluate the incidence of RCT, factors associated with transfusional requirements, and the number of donors, the VLBW baby clinic records of 66 babies who were discharged from the Valdivia Regional Hospital Neonatology Department between june 1995 and may 1997 were studied. The following characteristics of the study group were evaluated, concomitant pathology, number of transfusions and days in hospital. The risk factors associated with higher transfusional requirements were determined using odds ratio (OR). 89.4% received 1 or more transfusions, with a mean of 4.1 + 3.9, range 1-17. Characteristics associated with a greater number of RCT were birth weight of less than 1000 g (OR 10.0), gestional age for newborn less than 29 weeks (OR 7.9) and birth weight normal birth weight babies for) (OR 5.4). Associated pathology was broncho-pneumonia (OR 46.5), haemorrhage (OR 25.0), bronchopulmonar dysplasia (OR 16.4). The patients were exposed to a similar number of transfusions and number of donors <![CDATA[Dos nuevas mutaciones de glucosa 6 fosfato deshidrogenasa, G6PD Santiago y G6PD Calvo Mackenna]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0370-41062000000500007&lng=es&nrm=iso&tlng=es Se describen dos nuevas mutaciones que producen deficiencia de G6PD, ambas en niños chilenos con anemia hemolítica crónica no esferocítica (AHCNE). La mutación G6PD Santiago es debida a un cambio de arginina a prolina en el aminoácido 198, lo que lleva a una sustitución de guanina por citosina en el nucleótido 593 del exon 6. En la mutación G6PD Calvo Mackenna hay un cambio de valina a isoleucina en el aminoácido 380, lo que produce una sustitución de adenina por guanina en el nucleotido 1138 del exon 10 de la enzima. Los estudios para el diagnóstico de ellas se realizaron en "The Scripps and Research Institute de La Jolla, California, USA" por gentileza del Dr Ernest Beutler<hr/>Two undescribed mutations that produce G6PD deficiency in Chilean boys are documented. Both occurred in patients with hereditary non-spherocytic haemolytic anaemia. G6PD Santiago was due to an Arg-Pro change at amino acid 198 because of a C transition at nucleotide 593. G6PD Calvo Mackenna was due to a A-G transition at nucleotide 1138 resulting in a substitution of valine for isoleucine at amino acid 380. The studies were carried out in the Scripps Research Institute in La Jolla, California, USA by courtesy of Dr. Ernest Beutler <![CDATA[<I>Chlamydia trachomatis</I> en recién nacidos de un servicio de neonatología: Cuatro casos]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0370-41062000000500008&lng=es&nrm=iso&tlng=es La Chlamydia trachomatis (CT) es una bacteria que se transmite sexualmente y puede infectar al recién nacido (RN) en el canal del parto produciendo conjuntivitis, otitis y/o neumonía de evolución benigna, cuyo diagnóstico diferencial difícil. El tratamiento de elección son los macrólidos. El objetivo es presentar cuatro casos de prematuros extremos infectados por Chlamydia trachomatis en un Servicio de Neonatología. Estos niños nacieron por cesárea de madres cuyo estudio fue negativo para este agente, por lo que se plantea la posibilidad de transmisión no vertical, de gran interés epidemiológico. La confirmación de CT fue con inmunofluorescencia directa. Los signos de infección fueron relativamente precoces, siendo la eosinofilia un parámetro útil en la sospecha diagnóstica y monitorización de la respuesta al tratamiento. La radiografía de tórax no fue útil en el diagnóstico. En estos casos no fue posible confirmar a la CT como agente causal de neumonía o agravante de otras patologías pulmonares, sin embargo todos los RN respondieron bien al tratamiento con claritromicina. Por su asociación con parto prematuro se plantea el estudio de detección masiva o tratamiento profiláctico en embarazadas de riesgo<hr/>Chlamydia trachomatis (CT) is a bacteria which is sexually transmitted and infects the newborn as it passes through the birth canal. It may produce conjunctivitis, otitis and pneumonia of benign evolution whose differential diagnosis may be difficult. Macrolide antibiotics are the treatment of choice. We report 4 cases of preterm babies, born by caesarean section to CT negative mothers. This suggests the possiblility of non-vertical transmission, which is of great epidemiological interest. CT was detected using immunofluorescence. Infective signs developed early, with eosinophilia appearing to be be useful in suspecting the diagnosis and monitoring therapy. Chest x-ray was not useful as a diagnostic test. In these cases it was no possible to confirm that CT was the causal agent or aggrevating underlying pulmonary pathology. Nevertheless all responded to treatment with clarithromycin. Due to its association with premature birth it would be useful to screen for CT or treat prophylactically in at risk pregnancies <![CDATA[Diphyllobothriosis humana por infección por <I>Diphyllobotrhium pacificum </I>en un niño de 3 años en Antofagasta, Chile: infection in a 3 year old boy in Antofagasta, Chile]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0370-41062000000500009&lng=es&nrm=iso&tlng=es La diphyllobothriosis constituye una zoonosis relacionada con el consumo de carnes crudas o insuficientemente cocida de peces de aguas dulce o de mar. Se presenta un caso de diphyllobothriosis por Diphyllobothrium pacificum diagnosticado en Antofagasta en un niño de tres años, residente permanente en esta ciudad-puerto del Norte de Chile. El paciente eliminó espontáneamente una estróbila de 55 cm, a partir de la cual se realizó estudio morfométrico de proglótidas y huevos, concluyéndose que se trataba de un ejemplar de D. pacificum. Se administró tratamiento con praziquantel sin que se eliminaran nuevos ejemplares ni huevos, como tampoco se presentó anemia. Se investigó al grupo familiar constituido por cuatro personas sin encontrar otros infectados. Se destaca que de los 16 casos de diphyllobothriosis por D. pacificum documentados en Chile, tres corresponden a niños entre 7 y 3 años<hr/>Diphyllobothriosis is a zoonosis related to the consumption of crude or inadequately cooked sea or freshwater fish. We report a case of diphyllobothriosis caused by D. pacificum diagnosed in a 3 year old boy in the city port of Antofagasta in the north of Chile. The patient expelled one strobile of 55cm from which a morphometric study of proglotids and eggs demonstrated that it was a specimen of D. pacificum. He was treated with praziquantel but neither new strobiles or eggs were expelled. Haematological studies did not show any abnormalities. None of the family group were infected. Our finding is interesting in that among 16 cases documented in Chile, 3 correspond to children between 3 and 7 years <![CDATA[Estimación del tamaño muestral en estudios biomédicos por diferentes programas de computación]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0370-41062000000500010&lng=es&nrm=iso&tlng=es El cálculo del tamaño muestral en estudios biomédicos es parte indispensable de la investigación. El uso de programas computacionales facilita la tarea, pero presenta nuevos desafíos al ofrecer estimaciones variables. Objetivo: Presentar estimaciones del tamaño muestral empleando 6 programas, en estudios de medias, proporciones, cohortes y caso-control. Resultados: Se observaron diferencias a veces muy manifiestas en los cálculos realizados por los distintos programas. En el estudio de medias, EpiDat sugiere un tamaño que corresponde a la mitad de los otros. En proporciones, MedCalc calcula una muestra cuyo tamaño es el 58% del mayor propuesto. En cohortes y caso-control, con grupos de igual tamaño, la variación no es tan manifiesta, aunque no despreciable y depende de la prueba de hipótesis que se empleará. En caso-control con 4 controles por caso, la diferencia puede ser muy notoria entre EpiInfo y EpiDat pero Power incluye explicación en el sentido que depende de la prueba de hipótesis planeada usar. Conclusión: Importante ayuda se puede esperar de los programas que permiten estimar el tamaño de la muestra a investigar en diferentes situaciones, pero es indispensable disponer del manejo necesario de los conceptos bioestadísticos que subyacen a tales estimaciones para mejor decidir. Además el investigador debiera elegir y estar familiarizado con las características de un programa específico<hr/>Estimation of sample size is important in biomedical research studies. The use of statistical software requires a thorough study of potential drawbacks of these tools, especially when different program-mes may estimate different sample sizes when given the same basic data. Objective: To present sample size estimations with six different softwares in the study of means, proportions, cohorts and case-control designs. Results: Significant differences in sample size estimates were observed using the same basic data. When studying means EpiDat suggests half the sample size estimations performed by other softwares. In proportions Medcalc output is 58% of the larger estimation. In cohort or case-control studies with groups of the same size, estimations are not all equal though similar depending on hypothesis test applied. In a case-control study with 4 controls per case there is a striking difference between EpiInfo and EpiDat softwares, but Power provides an explanation establishing the need to consider the hypothesis test to be used. Conclusions: Valuable support is to be expected when estimating sample size in different scenarios by using appropriate softwares. However, the investigator should be aware of the biostatistical concepts underlying these estimations in order to take better decisions in computer assisted estimations. It is recommended to become familiar with one specific software <![CDATA[Caso clínico-radiológico para diagnóstico]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0370-41062000000500011&lng=es&nrm=iso&tlng=es El cálculo del tamaño muestral en estudios biomédicos es parte indispensable de la investigación. El uso de programas computacionales facilita la tarea, pero presenta nuevos desafíos al ofrecer estimaciones variables. Objetivo: Presentar estimaciones del tamaño muestral empleando 6 programas, en estudios de medias, proporciones, cohortes y caso-control. Resultados: Se observaron diferencias a veces muy manifiestas en los cálculos realizados por los distintos programas. En el estudio de medias, EpiDat sugiere un tamaño que corresponde a la mitad de los otros. En proporciones, MedCalc calcula una muestra cuyo tamaño es el 58% del mayor propuesto. En cohortes y caso-control, con grupos de igual tamaño, la variación no es tan manifiesta, aunque no despreciable y depende de la prueba de hipótesis que se empleará. En caso-control con 4 controles por caso, la diferencia puede ser muy notoria entre EpiInfo y EpiDat pero Power incluye explicación en el sentido que depende de la prueba de hipótesis planeada usar. Conclusión: Importante ayuda se puede esperar de los programas que permiten estimar el tamaño de la muestra a investigar en diferentes situaciones, pero es indispensable disponer del manejo necesario de los conceptos bioestadísticos que subyacen a tales estimaciones para mejor decidir. Además el investigador debiera elegir y estar familiarizado con las características de un programa específico<hr/>Estimation of sample size is important in biomedical research studies. The use of statistical software requires a thorough study of potential drawbacks of these tools, especially when different program-mes may estimate different sample sizes when given the same basic data. Objective: To present sample size estimations with six different softwares in the study of means, proportions, cohorts and case-control designs. Results: Significant differences in sample size estimates were observed using the same basic data. When studying means EpiDat suggests half the sample size estimations performed by other softwares. In proportions Medcalc output is 58% of the larger estimation. In cohort or case-control studies with groups of the same size, estimations are not all equal though similar depending on hypothesis test applied. In a case-control study with 4 controls per case there is a striking difference between EpiInfo and EpiDat softwares, but Power provides an explanation establishing the need to consider the hypothesis test to be used. Conclusions: Valuable support is to be expected when estimating sample size in different scenarios by using appropriate softwares. However, the investigator should be aware of the biostatistical concepts underlying these estimations in order to take better decisions in computer assisted estimations. It is recommended to become familiar with one specific software <![CDATA[Uso de medicamentos en constipación]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0370-41062000000500012&lng=es&nrm=iso&tlng=es El cálculo del tamaño muestral en estudios biomédicos es parte indispensable de la investigación. El uso de programas computacionales facilita la tarea, pero presenta nuevos desafíos al ofrecer estimaciones variables. Objetivo: Presentar estimaciones del tamaño muestral empleando 6 programas, en estudios de medias, proporciones, cohortes y caso-control. Resultados: Se observaron diferencias a veces muy manifiestas en los cálculos realizados por los distintos programas. En el estudio de medias, EpiDat sugiere un tamaño que corresponde a la mitad de los otros. En proporciones, MedCalc calcula una muestra cuyo tamaño es el 58% del mayor propuesto. En cohortes y caso-control, con grupos de igual tamaño, la variación no es tan manifiesta, aunque no despreciable y depende de la prueba de hipótesis que se empleará. En caso-control con 4 controles por caso, la diferencia puede ser muy notoria entre EpiInfo y EpiDat pero Power incluye explicación en el sentido que depende de la prueba de hipótesis planeada usar. Conclusión: Importante ayuda se puede esperar de los programas que permiten estimar el tamaño de la muestra a investigar en diferentes situaciones, pero es indispensable disponer del manejo necesario de los conceptos bioestadísticos que subyacen a tales estimaciones para mejor decidir. Además el investigador debiera elegir y estar familiarizado con las características de un programa específico<hr/>Estimation of sample size is important in biomedical research studies. The use of statistical software requires a thorough study of potential drawbacks of these tools, especially when different program-mes may estimate different sample sizes when given the same basic data. Objective: To present sample size estimations with six different softwares in the study of means, proportions, cohorts and case-control designs. Results: Significant differences in sample size estimates were observed using the same basic data. When studying means EpiDat suggests half the sample size estimations performed by other softwares. In proportions Medcalc output is 58% of the larger estimation. In cohort or case-control studies with groups of the same size, estimations are not all equal though similar depending on hypothesis test applied. In a case-control study with 4 controls per case there is a striking difference between EpiInfo and EpiDat softwares, but Power provides an explanation establishing the need to consider the hypothesis test to be used. Conclusions: Valuable support is to be expected when estimating sample size in different scenarios by using appropriate softwares. However, the investigator should be aware of the biostatistical concepts underlying these estimations in order to take better decisions in computer assisted estimations. It is recommended to become familiar with one specific software <![CDATA[Reflujo vesicoureteral]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0370-41062000000500013&lng=es&nrm=iso&tlng=es El cálculo del tamaño muestral en estudios biomédicos es parte indispensable de la investigación. El uso de programas computacionales facilita la tarea, pero presenta nuevos desafíos al ofrecer estimaciones variables. Objetivo: Presentar estimaciones del tamaño muestral empleando 6 programas, en estudios de medias, proporciones, cohortes y caso-control. Resultados: Se observaron diferencias a veces muy manifiestas en los cálculos realizados por los distintos programas. En el estudio de medias, EpiDat sugiere un tamaño que corresponde a la mitad de los otros. En proporciones, MedCalc calcula una muestra cuyo tamaño es el 58% del mayor propuesto. En cohortes y caso-control, con grupos de igual tamaño, la variación no es tan manifiesta, aunque no despreciable y depende de la prueba de hipótesis que se empleará. En caso-control con 4 controles por caso, la diferencia puede ser muy notoria entre EpiInfo y EpiDat pero Power incluye explicación en el sentido que depende de la prueba de hipótesis planeada usar. Conclusión: Importante ayuda se puede esperar de los programas que permiten estimar el tamaño de la muestra a investigar en diferentes situaciones, pero es indispensable disponer del manejo necesario de los conceptos bioestadísticos que subyacen a tales estimaciones para mejor decidir. Además el investigador debiera elegir y estar familiarizado con las características de un programa específico<hr/>Estimation of sample size is important in biomedical research studies. The use of statistical software requires a thorough study of potential drawbacks of these tools, especially when different program-mes may estimate different sample sizes when given the same basic data. Objective: To present sample size estimations with six different softwares in the study of means, proportions, cohorts and case-control designs. Results: Significant differences in sample size estimates were observed using the same basic data. When studying means EpiDat suggests half the sample size estimations performed by other softwares. In proportions Medcalc output is 58% of the larger estimation. In cohort or case-control studies with groups of the same size, estimations are not all equal though similar depending on hypothesis test applied. In a case-control study with 4 controls per case there is a striking difference between EpiInfo and EpiDat softwares, but Power provides an explanation establishing the need to consider the hypothesis test to be used. Conclusions: Valuable support is to be expected when estimating sample size in different scenarios by using appropriate softwares. However, the investigator should be aware of the biostatistical concepts underlying these estimations in order to take better decisions in computer assisted estimations. It is recommended to become familiar with one specific software <![CDATA[Traumatismo genitourinario en niños]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0370-41062000000500014&lng=es&nrm=iso&tlng=es El cálculo del tamaño muestral en estudios biomédicos es parte indispensable de la investigación. El uso de programas computacionales facilita la tarea, pero presenta nuevos desafíos al ofrecer estimaciones variables. Objetivo: Presentar estimaciones del tamaño muestral empleando 6 programas, en estudios de medias, proporciones, cohortes y caso-control. Resultados: Se observaron diferencias a veces muy manifiestas en los cálculos realizados por los distintos programas. En el estudio de medias, EpiDat sugiere un tamaño que corresponde a la mitad de los otros. En proporciones, MedCalc calcula una muestra cuyo tamaño es el 58% del mayor propuesto. En cohortes y caso-control, con grupos de igual tamaño, la variación no es tan manifiesta, aunque no despreciable y depende de la prueba de hipótesis que se empleará. En caso-control con 4 controles por caso, la diferencia puede ser muy notoria entre EpiInfo y EpiDat pero Power incluye explicación en el sentido que depende de la prueba de hipótesis planeada usar. Conclusión: Importante ayuda se puede esperar de los programas que permiten estimar el tamaño de la muestra a investigar en diferentes situaciones, pero es indispensable disponer del manejo necesario de los conceptos bioestadísticos que subyacen a tales estimaciones para mejor decidir. Además el investigador debiera elegir y estar familiarizado con las características de un programa específico<hr/>Estimation of sample size is important in biomedical research studies. The use of statistical software requires a thorough study of potential drawbacks of these tools, especially when different program-mes may estimate different sample sizes when given the same basic data. Objective: To present sample size estimations with six different softwares in the study of means, proportions, cohorts and case-control designs. Results: Significant differences in sample size estimates were observed using the same basic data. When studying means EpiDat suggests half the sample size estimations performed by other softwares. In proportions Medcalc output is 58% of the larger estimation. In cohort or case-control studies with groups of the same size, estimations are not all equal though similar depending on hypothesis test applied. In a case-control study with 4 controls per case there is a striking difference between EpiInfo and EpiDat softwares, but Power provides an explanation establishing the need to consider the hypothesis test to be used. Conclusions: Valuable support is to be expected when estimating sample size in different scenarios by using appropriate softwares. However, the investigator should be aware of the biostatistical concepts underlying these estimations in order to take better decisions in computer assisted estimations. It is recommended to become familiar with one specific software <![CDATA[Elección de empresas de acceso a Internet (ISP: Internet Service Provider)]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0370-41062000000500015&lng=es&nrm=iso&tlng=es El cálculo del tamaño muestral en estudios biomédicos es parte indispensable de la investigación. El uso de programas computacionales facilita la tarea, pero presenta nuevos desafíos al ofrecer estimaciones variables. Objetivo: Presentar estimaciones del tamaño muestral empleando 6 programas, en estudios de medias, proporciones, cohortes y caso-control. Resultados: Se observaron diferencias a veces muy manifiestas en los cálculos realizados por los distintos programas. En el estudio de medias, EpiDat sugiere un tamaño que corresponde a la mitad de los otros. En proporciones, MedCalc calcula una muestra cuyo tamaño es el 58% del mayor propuesto. En cohortes y caso-control, con grupos de igual tamaño, la variación no es tan manifiesta, aunque no despreciable y depende de la prueba de hipótesis que se empleará. En caso-control con 4 controles por caso, la diferencia puede ser muy notoria entre EpiInfo y EpiDat pero Power incluye explicación en el sentido que depende de la prueba de hipótesis planeada usar. Conclusión: Importante ayuda se puede esperar de los programas que permiten estimar el tamaño de la muestra a investigar en diferentes situaciones, pero es indispensable disponer del manejo necesario de los conceptos bioestadísticos que subyacen a tales estimaciones para mejor decidir. Además el investigador debiera elegir y estar familiarizado con las características de un programa específico<hr/>Estimation of sample size is important in biomedical research studies. The use of statistical software requires a thorough study of potential drawbacks of these tools, especially when different program-mes may estimate different sample sizes when given the same basic data. Objective: To present sample size estimations with six different softwares in the study of means, proportions, cohorts and case-control designs. Results: Significant differences in sample size estimates were observed using the same basic data. When studying means EpiDat suggests half the sample size estimations performed by other softwares. In proportions Medcalc output is 58% of the larger estimation. In cohort or case-control studies with groups of the same size, estimations are not all equal though similar depending on hypothesis test applied. In a case-control study with 4 controls per case there is a striking difference between EpiInfo and EpiDat softwares, but Power provides an explanation establishing the need to consider the hypothesis test to be used. Conclusions: Valuable support is to be expected when estimating sample size in different scenarios by using appropriate softwares. However, the investigator should be aware of the biostatistical concepts underlying these estimations in order to take better decisions in computer assisted estimations. It is recommended to become familiar with one specific software <![CDATA[Is adolescent pregnancy a risk factor for low birth eight? (Brasil)]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0370-41062000000500016&lng=es&nrm=iso&tlng=es Objetivo: O objetivo deste trabalho foi estudar a gestação na adolescência como possível fator de risco para o baixo peso ao nascer. Métodos: Foi realizado um estudo caso-controle. Foram entrevistadas e comparadas 354 mães de recém-nascidos de peso ao nascer inferior à 2.500 g e outras 354 que tiveram filhos de 3.000 g ou mais, cujos partos aconteceram na Maternidade de Campinas. As informações incluíram além da idade materna, outras variáveis tidas como de risco para o baixo peso ao nascer. Foi usada Análise de Regressão Logística Múltipla para controlar possíveis influências dessas variáveis. Resultados: As adolescentes representaram 22,9% das mães dos recém-nascidos de baixo peso. Não se observou risco aumentado para o baixo peso ao nascer entre essas mães (OR = 0,72; 95% IC = 0,45-1,14; p = 0,16) quando comparadas com aquelas de idade variando de 20 a 34 anos (resultado ajustado para renda, estado civil, escolaridade, cor, antecedentes gestacionais, assistência no período pré-natal, exposição ao fumo e cafeína, hipertensão arterial, peso prévio à gestação e o trabalho fora de casa). Ao se realizarem análises complementares, observou-se que a gravidez na adolescência se apresentou como possível fator de proteção contra o retardo de crescimento intrauterino (OR = 0,24; 95% IC = 0,10-0,56; p = 0,001). Conclusão: Neste estudo, a gravidez na adolêscencia não representou maior risco para a ocorrência de baixo peso ao nascer na população estudada, quando a influência de outros fatores psicossociais desfavoráveis, antecedentes gestacionais de risco, exposição ao fumo e cuidados inadequados de pré-natal foi afastada<hr/>Objective: This paper was designed to study the pregnancy in adolescence as a risk factor for low birth weight. Methodology: A case-control study was designed, including 354 mothers whose babies’weight was less than 2.5 kg and another group of the same size, with babies of 3.0 kg or more. All deliveries took place at Maternidade de Campinas, and all mothers were interviewed and compared. Besides mother’s age, other variables that could offer risk of low birth weight were also evaluated. A multiple logistic regression analysis was applied, to control possible influences of these variables. Results: Adolescents accounted for 22.9% of the mothers whose babies had low birth weight. The risk of low birth weight among this group (OR = 0.72; 95% IC = 0.45-1.14; p = 0.16) was not considered greater when compared with that of mothers between 20 and 34 years old (before and after correction for income, marital status, educational level, race, previous pregnancies, prenatal assistance, exposure to smoking and caffeine, arterial hypertension, weight prior to pregnancy and employment). Complementary analysis showed that pregnancy in adolescence is a protection factor against intrauterine growth retardation (OR = 0.24; 95% IC = 0.10-0.56; p = 0.001). Conclusion: In this population, pregnancy in adolescence did not represent a greater risk for occurrence of low birth weight, when others factors like psychosocial, pre-gestational risks, smoking and poor prenatal care were controlled for <![CDATA[<I>A simple strategy increases mothers’knowledge of breastfeeding and improves the breastfeeding rates (Brasil)</I>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0370-41062000000500017&lng=es&nrm=iso&tlng=es Objetivo: Avaliar o conhecimento das mães em aleitamento materno antes e após orientação fornecida no período pós-parto e sua relação com a prevalência de amamentação. Métodos: Foi realizado um ensaio-clínico com 405 mães de crianças normais nascidas no Hospital de Clínicas de Porto Alegre entre julho e dezembro de 1994, cujo procedimento de intervenção consistiu de um vídeo abordando tópicos básicos sobre aleitamento materno, de um folheto explicativo e da livre discussão após o video. As primeiras 208 mães constituíram o Grupo Controle e as restantes 197, o Grupo Experimental. Todas as mães responderam a um questionário de identificação e a um teste de conhecimentos prévios sobre aleitamento materno na maternidade. As mães dos dois grupos foram acompanhadas por intermédio de visitas domiciliares ao final do primeiro, do segundo, do quarto e do sexto mês ou até a interrupção da amamentação, se fosse o caso. Ao final do primeiro més, as máes foram submetidas ao mesmo teste de conhecimentos aplicado logo após o parto. A técnica de regressão logística foi utilizada para avaliar a associação entre o conhecimento da mãe em aleitamento materno e a prevalência da amamentação. Resultados: As mães que receberam a intervenção (Grupo Experimental) tiveram um escore significativamente maior no teste de conhecimentos em aleitamento materno ao final do primeiro mês quando comparadas coro as mães do Grupo Controle (17,0 versus 14,7). A intervenção aumentou a chance das mães em 1,7 vezes de obter em um escore acima da média. Por sua vez, as mães cujos escores ficaram acima da média tiveram uma chance 8,2 vezes maior de estar amamentando exclusivamente no final do terceiro mês e duas vezes maior de estarem amamentando no final do sexto mês. Conclusão: Estratégias simples para aumentar o conhecimento das mães sobre aleitamento materno podem ter impacto positivo nas taxas de amamentação<hr/>Objective: To assess mothers’ knowledge of breastfeeding before and after guidance supplied during the postpartum period and its relationship to the prevalence of breastfeeding. Methods: A clinical trial was performed with 405 mothers of normal children born at Hospital de Clínicas de Porto Alegre from July to December 1994. The intervention consisted of guidance given by means of a video film discussing basic topics on breastfeeding, an explanatory leaflet and open discussion after the video. The first 208 mothers constituted the Control Group and the remaining 197 the Experimental Group. All mothers answered a question form for identification purposes and a test on previous knowledge regarding breastfeeding in the maternity ward. The mothers in both groups were followed by means of home visits at the end of the first, second, fourth and sixth months, or until they stopped breastfeeding. At the end of the first month the mothers were submitted to the same test given right after delivery. Logistic regression was used to evaluate the association between the mothers’ knowledge of breastfeeding and the prevalence of breastfeeding. Results: The mothers who received the intervention (Experimental Group) had a significantly higher score in the tests on knowledge of breastfeeding at the end of the first month as compared with the mothers in the Control Group (17.0 versus 14.7). The intervention increased by 1.7 mother’s chances of achieving a score above the average. The mothers whose scores were above the average had a 8.2 higher chance of being breastfeeding exclusively at the end of the third month and twice as high of still being breastfeeding at the end of the sixth month. Conclusion: Simple strategies to increase mothers’ knowledge regarding breastfeeding can have a positive impact on breastfeeding rates <![CDATA[NOTICIAS]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0370-41062000000500018&lng=es&nrm=iso&tlng=es Objetivo: Avaliar o conhecimento das mães em aleitamento materno antes e após orientação fornecida no período pós-parto e sua relação com a prevalência de amamentação. Métodos: Foi realizado um ensaio-clínico com 405 mães de crianças normais nascidas no Hospital de Clínicas de Porto Alegre entre julho e dezembro de 1994, cujo procedimento de intervenção consistiu de um vídeo abordando tópicos básicos sobre aleitamento materno, de um folheto explicativo e da livre discussão após o video. As primeiras 208 mães constituíram o Grupo Controle e as restantes 197, o Grupo Experimental. Todas as mães responderam a um questionário de identificação e a um teste de conhecimentos prévios sobre aleitamento materno na maternidade. As mães dos dois grupos foram acompanhadas por intermédio de visitas domiciliares ao final do primeiro, do segundo, do quarto e do sexto mês ou até a interrupção da amamentação, se fosse o caso. Ao final do primeiro més, as máes foram submetidas ao mesmo teste de conhecimentos aplicado logo após o parto. A técnica de regressão logística foi utilizada para avaliar a associação entre o conhecimento da mãe em aleitamento materno e a prevalência da amamentação. Resultados: As mães que receberam a intervenção (Grupo Experimental) tiveram um escore significativamente maior no teste de conhecimentos em aleitamento materno ao final do primeiro mês quando comparadas coro as mães do Grupo Controle (17,0 versus 14,7). A intervenção aumentou a chance das mães em 1,7 vezes de obter em um escore acima da média. Por sua vez, as mães cujos escores ficaram acima da média tiveram uma chance 8,2 vezes maior de estar amamentando exclusivamente no final do terceiro mês e duas vezes maior de estarem amamentando no final do sexto mês. Conclusão: Estratégias simples para aumentar o conhecimento das mães sobre aleitamento materno podem ter impacto positivo nas taxas de amamentação<hr/>Objective: To assess mothers’ knowledge of breastfeeding before and after guidance supplied during the postpartum period and its relationship to the prevalence of breastfeeding. Methods: A clinical trial was performed with 405 mothers of normal children born at Hospital de Clínicas de Porto Alegre from July to December 1994. The intervention consisted of guidance given by means of a video film discussing basic topics on breastfeeding, an explanatory leaflet and open discussion after the video. The first 208 mothers constituted the Control Group and the remaining 197 the Experimental Group. All mothers answered a question form for identification purposes and a test on previous knowledge regarding breastfeeding in the maternity ward. The mothers in both groups were followed by means of home visits at the end of the first, second, fourth and sixth months, or until they stopped breastfeeding. At the end of the first month the mothers were submitted to the same test given right after delivery. Logistic regression was used to evaluate the association between the mothers’ knowledge of breastfeeding and the prevalence of breastfeeding. Results: The mothers who received the intervention (Experimental Group) had a significantly higher score in the tests on knowledge of breastfeeding at the end of the first month as compared with the mothers in the Control Group (17.0 versus 14.7). The intervention increased by 1.7 mother’s chances of achieving a score above the average. The mothers whose scores were above the average had a 8.2 higher chance of being breastfeeding exclusively at the end of the third month and twice as high of still being breastfeeding at the end of the sixth month. Conclusion: Simple strategies to increase mothers’ knowledge regarding breastfeeding can have a positive impact on breastfeeding rates <![CDATA[RESEÑA DE LIBROS]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0370-41062000000500019&lng=es&nrm=iso&tlng=es Objetivo: Avaliar o conhecimento das mães em aleitamento materno antes e após orientação fornecida no período pós-parto e sua relação com a prevalência de amamentação. Métodos: Foi realizado um ensaio-clínico com 405 mães de crianças normais nascidas no Hospital de Clínicas de Porto Alegre entre julho e dezembro de 1994, cujo procedimento de intervenção consistiu de um vídeo abordando tópicos básicos sobre aleitamento materno, de um folheto explicativo e da livre discussão após o video. As primeiras 208 mães constituíram o Grupo Controle e as restantes 197, o Grupo Experimental. Todas as mães responderam a um questionário de identificação e a um teste de conhecimentos prévios sobre aleitamento materno na maternidade. As mães dos dois grupos foram acompanhadas por intermédio de visitas domiciliares ao final do primeiro, do segundo, do quarto e do sexto mês ou até a interrupção da amamentação, se fosse o caso. Ao final do primeiro més, as máes foram submetidas ao mesmo teste de conhecimentos aplicado logo após o parto. A técnica de regressão logística foi utilizada para avaliar a associação entre o conhecimento da mãe em aleitamento materno e a prevalência da amamentação. Resultados: As mães que receberam a intervenção (Grupo Experimental) tiveram um escore significativamente maior no teste de conhecimentos em aleitamento materno ao final do primeiro mês quando comparadas coro as mães do Grupo Controle (17,0 versus 14,7). A intervenção aumentou a chance das mães em 1,7 vezes de obter em um escore acima da média. Por sua vez, as mães cujos escores ficaram acima da média tiveram uma chance 8,2 vezes maior de estar amamentando exclusivamente no final do terceiro mês e duas vezes maior de estarem amamentando no final do sexto mês. Conclusão: Estratégias simples para aumentar o conhecimento das mães sobre aleitamento materno podem ter impacto positivo nas taxas de amamentação<hr/>Objective: To assess mothers’ knowledge of breastfeeding before and after guidance supplied during the postpartum period and its relationship to the prevalence of breastfeeding. Methods: A clinical trial was performed with 405 mothers of normal children born at Hospital de Clínicas de Porto Alegre from July to December 1994. The intervention consisted of guidance given by means of a video film discussing basic topics on breastfeeding, an explanatory leaflet and open discussion after the video. The first 208 mothers constituted the Control Group and the remaining 197 the Experimental Group. All mothers answered a question form for identification purposes and a test on previous knowledge regarding breastfeeding in the maternity ward. The mothers in both groups were followed by means of home visits at the end of the first, second, fourth and sixth months, or until they stopped breastfeeding. At the end of the first month the mothers were submitted to the same test given right after delivery. Logistic regression was used to evaluate the association between the mothers’ knowledge of breastfeeding and the prevalence of breastfeeding. Results: The mothers who received the intervention (Experimental Group) had a significantly higher score in the tests on knowledge of breastfeeding at the end of the first month as compared with the mothers in the Control Group (17.0 versus 14.7). The intervention increased by 1.7 mother’s chances of achieving a score above the average. The mothers whose scores were above the average had a 8.2 higher chance of being breastfeeding exclusively at the end of the third month and twice as high of still being breastfeeding at the end of the sixth month. Conclusion: Simple strategies to increase mothers’ knowledge regarding breastfeeding can have a positive impact on breastfeeding rates