Abstract Objective: The perfusion profile of vestibular schwannomas (VSs) and the factors that influence it have yet to be determined. Materials and Methods: Twenty patients with sporadic VS were analyzed by calculating parameters related to the extravascular extracellular space (EES)—the volume transfer constant between a vessel and the EES (Ktrans); the EES volume per unit of tissue volume (Ve); and the rate transfer constant between EES and blood plasma (Kep)—as well as the relative cerebral blood volume (rCBV), and by correlating those parameters with the size of the tumor and its structure (solid, cystic, or heterogeneous). Results: Although Ktrans, Ve, and Kep were measurable in all tumors, rCBV was measurable only in large tumors. We detected a positive correlation between Ktrans and rCBV (r = 0.62, p = 0.031), a negative correlation between Ve and Kep (r = –0.51, p = 0.021), and a positive correlation between Ktrans and Ve only in solid VSs (r = 0.64, p = 0.048). Comparing the means for small and large VSs, we found that the former showed lower Ktrans (0.13 vs. 0.029, p < 0.001), higher Kep (0.68 vs. 0.46, p = 0.037), and lower Ve (0.45 vs. 0.83, p < 0.001). The mean Ktrans was lower in the cystic portions of cystic VSs than in their solid portions (0.14 vs. 0.32, p < 0.001), as was the mean Ve (0.37 vs. 0.78, p < 0.001). There were positive correlations between the solid and cystic portions for Ktrans (r = 0.71, p = 0.048) and Kep (r = 0.74, p = 0.037). Conclusion: In VS, tumor size appears to be consistently associated with perfusion values. In cystic VS, the cystic portions seem to have lower Ktrans and Ve than do the solid portions.

Resumo Objetivo: O perfil de perfusão do schwannoma vestibular (SV) não tem sido estudado, nem os fatores que o influenciam. Materiais e Métodos: Vinte pacientes com SV esporádico foram analisados usando Ktrans, Ve, Kep e rCBV e correlacionados com tamanho e estádio cístico. Resultados: Ktrans, Ve e Kep foram medidos em todos os casos. rCBV só foi possível em tumores grandes. Ktrans e rCBV estavam correlacionados positivamente (r = 0,62, p = 0, 0 31 ) . Ve e Kep estavam negativamente correlacionados (r = –0,51, p = 0,021). Ktrans estava correlacionado positivamente com Ve em SVs sólidos (r = 0,64, p = 0,048). Em SVs pequenos, Ktrans foi menor (0,13 vs 0,029, p < 0,001), Kep foi maior (0,68 vs 0,46, p = 0,037) e Ve foi menor (0,45 vs 0,83, p < 0,001) que nos SVs grandes. Ktrans e Ve foram menores dentro dos cistos que nas porções solidas dos SVs císticos (0,14 vs 0,32, p < 0,001; 0,37 vs 0,78, p < 0.001, respectivamente). Foi encontrada correlação positiva em Ktrans (r = 0,71, p = 0,048) e Kep (r = 0,74, p = 0,037) entre as áreas sólidas e císticas. Conclusão: Nos SVs, o tamanho está consistentemente associado com os valores da perfusão. Nos SVs císticos, as porções císticas parecem ter valores menores de Ktrans e Ve do que nas porções sólidas.

Introduction. Inadequate antibiotic use is associated with an increased emergence of resistant microorganisms, higher morbidity and mortality rates, and an impact on public health. Objective. To assess the effectiveness of a program aimed at improving the use of antimicrobials in patients hospitalized at Hospital Garrahan. Material and Methods. Prospective, longitudinal, before and after study with no control group. Study period: From November 1st, 2010 to June 30th, 2011. Patients receiving parenteral antibiotics were included. Newborn infants, burned patients and those receiving prophylactic antibiotics were excluded. The periods before and after implementing discussion and monitoring workshops for antibiotic prescription and distributing treatment guidelines were compared. An univariate analysis and a multiple logistic regression study were performed (STATA 8.0). Results. In the pre-interventionperiod,376patients were included; of them, 35.6% had received inadequate treatment. The multiple regression analysis showed that the endpoints for inadequate antibiotic use were acute lower respiratory tract infection (OR: 3.80; 95% CI: 1.35-3.26; p=0.04), fever without a source in hospitalized patients (OR: 5.55; 95% CI: 2.43-12.6; p < 0.01), and febrile neutropenia (OR: 0.29; 95% CI: 0.10-0.7; p < 0.01). In the post-intervention period, 357 patients were included; 21.5% had received inadequate treatment. A reduction in inadequate antibiotic prescription was observed compared to the pre-intervention period (p < 0.01). The multiple regression analysis showed that endpoints for inadequate use were skin and soft tissue infections (OR: 0.33; 95% CI: 0.13-0.93; p = 0.035), and febrile neutropenia (OR: 0.48; 95% CI: 0.220.94; p= 0.04). Conclusion. The program was effective and allowed to improve antibiotic prescription practices in hospitalized children.

Introducción. El uso inapropiado de antibióticos se relaciona con el incremento de los microorganismos resistentes, mayor morbimortalidad e impacto en la salud pública. Objetivo. Evaluar la efectividad de un programa para mejorar la adecuación del uso de los antimicrobianos en los pacientes internados en el Hospital Garrahan. Material y métodos. Estudio prospectivo, longitudinal, antes-después, sin grupo control. Período de estudio: del 1/7/2010 al30/6/2011. Se incluyeron pacientes con antibiótico parenteral. Se excluyeron los recién nacidos, quemados y aquellos con antibiótico como profilaxis. Se comparó el período previo y posterior a la implementación de talleres de discusión y monitoreo de indicaciones de antibióticos y la difusión de guías de tratamiento. Se realizó análisis univariado y estudio de regresión logística múltiple (STATA 8.0). Resultados. En el período preintervención, se incluyeron 376 pacientes; el 35,6% recibió tratamiento inadecuado. En el análisis de regresión múltiple, las variables finales de uso inadecuado fueron la infección respiratoria aguda baja (OR 3,80; IC 95% 1,35-3,26; p= 0,04), la fiebre sin foco en el paciente internado (OR 5,55; IC 95% 2,43-12,6; p < 0,01) y la neutropenia febril (OR 0,29; IC 95% 0,10-0,7; p < 0,01). Postintervención: se incluyeron 357 pacientes; 21,5% recibió tratamiento inapropiado. Se observó un descenso en la prescripción antibiótica inadecuada respecto al período preintervención (p < 0,01). En el análisis de regresión múltiple, las variables finales respecto al uso inadecuado fueron infección de piel y partes blandas (OR 0,33; IC 95% 0,13-0,93; p= 0,035) y neutropenia febril (OR 0,48; IC 95% 0,22-0,94; p= 0,04). Conclusión. El programa fue efectivo. Permitió mejorar las prácticas de prescripción de antibióticos en pacientes pediátricos hospitalizados.

OBJECTIVE: Determine the reasons for inappropriate prescription of antibiotics and identify opportunities to improve prescription of these drugs in pediatric patients hospitalized in intermediate and intensive care units. METHODS: A prospective, descriptive longitudinal study was conducted of pediatric patients in intermediate and intensive care units who received parenteral administration of antibiotics, with the exception of newborns, burn unit patients, and surgical prophylaxis patients. A univariate analysis and multiple logistic regression were performed. RESULTS: A total of 376 patients with a median of age of 50 months were studied (interquartile range [IQR] 14.5-127 months). Out of the total patients studied, 75% had one or more underlying conditions. A total of 40.6% of these patients had an oncologic pathology and 33.5% had neurological conditions. The remaining 25.9% had other underlying conditions. Antibiotic treatment was inappropriate in 35.6% of the patients studied (N = 134). In 73 (54.4%) of the 134 cases, inappropriate use was due to the type of antibiotic prescribed, the dose administered, or the treatment period. The 61 (45.5%) remaining cases did not require antibiotic treatment. In the multivariate analysis, the risk factors for inappropriate use of antibiotics were: administration of ceftriaxone OR 2 (95% CI, 1.3-3.7; P = 0.02); acute lower respiratory tract infection OR 1.8 (95% CI, 1.1-3.3; P < 0.04); onset of fever of unknown origin in hospital inpatients OR 5.55 (95% CI, 2.5-12; P < 0.0001); and febrile neutropenia OR 0.3 (95% CI, 0.1-0.7; P = 0.009). CONCLUSIONES: Inappropriate use of antibiotics was less common in the clinical conditions that were well-characterized. Prescribing practices that could be improved were identified through the preparation and circulation of guidelines for antibiotic use in hospital inpatients.

OBJETIVO: Determinar los motivos de la prescripción inadecuada de antibióticos y detectar oportunidades de mejorar la prescripción de dichos medicamentos en el caso de pacientes pediátricos hospitalizados en unidades de cuidados intermedios e intensivos. MÉTODOS: Estudio prospectivo, descriptivo y longitudinal de pacientes pediátricos internados en unidades de cuidados intermedios e intensivos que recibían antibióticos por vía parenteral, con excepción de los recién nacidos, pacientes de la unidad de quemados y pacientes en profilaxis quirúrgica. Se realizó un análisis univariado y regresión logística múltiple. RESULTADOS: Se estudió a 376 pacientes, con una mediana de edad de 50 meses (rango intercuartilo [RIC] 14,5-127 meses). Del total de pacientes estudiados, 75,0% tenía una enfermedad de base o más. De esos últimos, 40,6% tenía una patología oncológica y 33,5%, neurológica; el restante 25,9% presentaba otras enfermedades de base. El tratamiento antibiótico fue inadecuado en 35,6% de los pacientes estudiados (n = 134). En 73 (54,4%) de los 134 casos, el uso inadecuado se debió al tipo de antibiótico recetado, la dosis administrada o la duración del tratamiento. Los 61 (45,5%) casos restantes no tenían indicación de tratamiento antibiótico. En el análisis multivariado, los factores de riesgo de uso inadecuado de antibióticos fueron: la administración de ceftriaxona: OR 2 (IC 95% 1,3-3,7; P = 0,02); infección agudade vías respiratorias inferiores: OR 1,8 (IC 95%1, 1-3,3; P < 0,04); la aparición de fiebre sin foco en el paciente internado: OR 5,55 (IC 95% 2,5-12; P < 0,0001) y la neutropenia febril OR 0,3 (IC 95% 0,1-0,7) P = 0,009. CONCLUSIONES: Los cuadros clínicos mejor caracterizados presentaron menor uso inadecuado de antibióticos. Se identificaron prácticas de prescripción que podrían ser mejoradas mediante la elaboración y difusión de guías de manejo del uso de antibióticos en pacientes internados.