The calibration of a prototype occluded ear simulator designed for neonatal hearing assessment applications.

An innovative family of ear simulators has been conceived for the calibration and traceability of audiometric equipment. Each device within the family has been designed for a particular key age group, covering neonates through to adults. The age-specific ear simulators are intended to improve the quality of hearing assessment measurements for all test subject age groups, and will be proposed as the next generation of standardised ear simulators for audiometric applications. The family of ear simulators shares a common design and modeling approach, and the first prototype devices for neonatal applications have been manufactured. The objectives of this study were to develop calibration methods, verify conformance to the design goals, demonstrate that the device is capable of being calibrated reliably, and show that its performance is ultimately suitable for international standardisation and eventual adoption into clinical practices. Four national measurement institutes took part in a round-robin calibration comparison and an analysis of the results showed that these objectives were achieved.

Relative variance of the mean-squared pressure in multimode media: rehabilitating former approaches.

The commonly accepted model for the relative variance of transmission functions in room acoustics, derived by Weaver, aims at including the effects of correlation between eigenfrequencies. This model is based on an analytical expression of the relative variance derived by means of an approximated correlation function. The relevance of the approximation used for modeling such correlation is questioned here. Weaver's model was motivated by the fact that earlier models derived by Davy and Lyon assumed independent eigenfrequencies and led to an overestimation with respect to relative variances found in practice. It is shown here that this overestimation is due to an inadequate truncation of the modal expansion, and to an improper choice of the frequency range over which ensemble averages of the eigenfrequencies is defined. An alternative definition is proposed, settling the inconsistency; predicted relative variances are found to be in good agreement with experimental data. These results rehabilitate former approaches that were based on independence assumptions between eigenfrequencies. Some former studies showed that simpler correlation models could be used to predict the statistics of some field-related physical quantity at low modal overlap. The present work confirms that this is also the case when dealing with transmission functions.

Salmonella peritonitis in a patient on automated peritoneal dialysis.

We describe the clinical course of a case of peritonitis caused by Salmonella sp. after an episode of intestinal salmonellosis, and a brief review of the literature is also done.

Dynamic behavior of the circular membrane of an electrostatic microphone: effect of holes in the backing electrode.

Today, several applications require using electrostatic microphones in environments and/or in frequency ranges, which are significantly different from those they were designed for. When low uncertainties on the behavior of acoustic fields, generated or measured by these transducers, are required, the displacement field of the diaphragm of the transducers (which can be highly nonuniform in the highest frequency range) must be characterized with an appropriate accuracy. An analytical approach, which leads to results depending on the location of the holes in the backing electrode (i.e., depending on the azimuthal coordinate) not available until now (regarding the displacement field of the membrane in the highest frequency range, up to 100 kHz), is presented here. The holes and the slit surrounding the electrode are considered as localized sources described by their volume velocity in the propagation equation governing the pressure field in the air gap (not by nonuniform boundary conditions on the surface of the backing electrode as usual). Experimental results, obtained from measurements of the displacement field of the membrane using a laser scanning vibrometer, are presented and compared to the theoretical results.

[APACHE II and ATN-ISS in acute renal failure (ARF) in intensive care unit (ICU) and non-ICU]. / Uso do escore prognóstico APACHE II e ATN-ISS em insuficiência renal aguda tratada dentro e fora da unidade de terapia intensiva.

INTRODUCTION: Acute renal failure (ARF) remains highly prevalent with a high rate of morbidity and mortality. OBJECTIVE: of this study was to compare use of the APACHE II scoring prognosis with that of the ATN-ISS to determine whether the APACHE II could be used for patients with ARF outside the ICU. METHODS: For this purpose, 205 patients with ARF were accompanied in a prospective cohort. Demographic data, preexisting conditions, organ failure and characteristics of ARF were analyzed. The prognostic scores were performed with the assessment of a nephrologist. RESULTS: The mean age was 52 +/- 18 years, 50% were male, 69% were white, 45% were treated in ICU and 55% in other units. Mortality in the ICU group was 85% and in the non-ICU group 18%. Factors that correlated with higher mortality were more prevalent in the ICU group: age, male, hospitalization with ARF, organ failure, sepsis, septic IRA, oliguria and need of dialysis. Overall, the prognostic markers were the same for both the ICU and non-ICU groups. The discrimination with the APACHE II was similar in both, ICU and non-ICU groups and calibration was better in the non-ICU group. The ATN-ISS achieved good discrimination in both the ICU and non-ICU groups, but, regarding calibration, there was a discreet over estimating of mortality in the non-ICU group. The ATN-ISS showed a greater capacity for discrimination than the APACHE II in both the ICU and non-ICU groups. CONCLUSION: It was concluded that the APACHE II and ATN-ISS scores could be used for stratification of risk in patients with ARF treated outside of the ICU in Brazil.

Insuficiência renal aguda nefrotóxica: prevalência, evolução clínica e desfecho / Nephrotoxic acute renal failure: prevalence, clinical course and outcome

Introdução: A insuficiência renal aguda (IRA) nefrotóxica é frequente e importante causa de morbimortalidade. objetivo: Avaliar a prevalência, o curso clínico e o desfecho da IRA nefrotóxica. pacientes e Métodos: Coorte histórica realizada em um hospital de ensino terciário, no período de fevereiro a novembro de 1997. Foram incluídos pacientes acima de 12 anos, com diagnóstico de IRA, acompanhados pela equipe de Interconsulta de Nefrologia. Foram excluídos transplantados renais, portadores de insuficiência renal crônica, dialisados por intoxicação exógena e aqueles transferidos de hospital durante o tratamento. Resultados: Dos 234 pacientes acompanhados, 12% apresentaram IRA nefrotóxica e 24%, IRA multifatorial associada ao uso de drogas nefrotóxicas. Entre as comorbidades mais prevalentes, estão hipertensão arterial, hepatopatias, neoplasias, insuficiência cardíaca congestiva e diabetes mellitus. Quinze por cento necessitaram de diálise, e o tipo mais frequentemente usado foi hemodiálise venovenosa contínua; 42% eram oligúricos, 44,7% evoluíram para óbito e 33% recuperaram a função renal. Antibióticos, AINH e contraste radiológico foram as drogas nefrotóxicas mais prevalentes. Os medicamentos nefrotóxicos implicados foram, em ordem de frequência, vancomicina, aminoglicosídeos, aciclovir, quimioterápicos e contraste radiológico. Hepatopatia foi a única variável com significância estatística (p=0,03, IC= 1,08 a 6,49) em análise multivariada. Na comparação entre IRA nefrotóxica, houve aumento da mortalidade proporcionalmente aos dias de internação. Conclusão: IRA nefrotóxica é frequente, grave e deve ser continuamente monitorada, tanto ambulatorialmente quanto no ambiente intra-hospitalar.

Background: Acute renal failure (ARF) is frequent and important cause of morbidity and mortality. Objective: To evaluate the prevalence, clinical course and outcome of nephrotoxic ARF. Patients and Methods: This historical cohort study conducted in a tertiary hospital in the period from February to November 1997. We included patients over 12 years, diagnosed with ARF, accompanied by a team of nephrologists. Were excluded from renal transplant patients, patients with chronic renal failure, dialysis with exogenous poisoning and those transferred to hospital during treatment. Results: Of 234 patients enrolled, 12% had nephrotoxic ARF, and 24% multifactorial ARF associated with the use of nephrotoxic drugs. Among the most prevalent comorbidities are arterial hypertension, liver diseases, cancer, congestive heart failure and diabetes mellitus. Fifteen percent required dialysis, and the type most often used was continuous venovenous hemodialysis, 42% were oliguric, 44.7% died and 33% recovered renal function. Antibiotics, NSAIDs and contrast radiological nephrotoxic drugs were more prevalent. The nephrotoxic drugs were, in order of frequency, vancomycin, aminoglycosides, acyclovir, chemotherapy and radiological contrast. Liver was the only variable with statistical significance (p = 0.03, CI = 1.08 to 6.49) in multivariate analysis. In comparison nephrotoxic ARF, there was increased mortality proportional to the length of hospitalization. Conclusion: Nephrotoxic ARF is common, serious and must be continuously monitored, both outpatient and in-hospital setting.

Uso do escore prognóstico APACHE II e ATN-ISS em insuficiência renal aguda tratada dentro e fora da unidade de terapia intensiva / APACHE II and ATN-ISS in acute renal failure (ARF) in intensive care unit (ICU) and non-ICU

INTRODUÇÃO: A insuficiência renal aguda (IRA) mantém alta prevalência, morbidade e mortalidade. OBJETIVO: Comparar o uso do escore prognóstico APACHE II com o ATN-ISS e determinar se o APACHE II pode ser utilizado para pacientes com IRA, fora da UTI. MÉTODOS: Coorte prospectiva, 205 pacientes com IRA. Analisamos dados demográficos, condições pré-existentes, falência de órgãos e características da IRA. Os escores prognósticos foram realizados no dia da avaliação do nefrologista. RESULTADOS: A média de idade foi 52 ± 18 anos, 50 por cento eram do sexo masculino, 69 por cento eram brancos, 45 por cento foram tratados em UTI e 55 por cento em outras unidades. A mortalidade no grupo UTI foi 85 por cento e no grupo não-UTI foi 18 por cento. Os fatores que se correlacionaram com maior mortalidade foram mais prevalentes na UTI: idade, sexo masculino, IRA hospitalar, falência de órgãos, sepse, IRA séptica, oligúria e necessidade dialítica. No contexto geral, os marcadores prognósticos foram os mesmos para os grupos UTI e não-UTI. O APACHE II obteve discriminação similar nos grupos UTI e não-UTI e sua calibração foi melhor no grupo não-UTI. O ATN-ISS obteve boa discriminação tanto no grupo UTI quanto não-UTI, porém, com relação à calibração houve discreta superestimação da mortalidade no grupo não-UTI. O ATN-ISS apresentou melhor capacidade de discriminação do que o APACHE II nos grupos UTI e não-UTI. CONCLUSÃO: Concluímos que os escores APACHE II e ATN-ISS podem ser utilizados para a estratificação de risco em pacientes com IRA tratados fora da UTI em nosso meio.

INTRODUCTION: Acute renal failure (ARF) remains highly prevalent with a high rate of morbidity and mortality. OBJECTIVE: of this study was to compare use of the APACHE II scoring prognosis with that of the ATN-ISS to determine whether the APACHE II could be used for patients with ARF outside the ICU. METHODS: For this purpose,, 205 patients with ARF were accompanied in a prospective cohort. Demographic data, preexisting conditions, organ failure and characteristics of ARF were analyzed. The prognostic scores were performed with the assessment of a nephrologist. RESULTS: The mean age was 52 ± 18 years, 50 percent were male, 69 percent were white, 45 percent were treated in ICU and 55 percent in other units. Mortality in the ICU group was 85 percent and in the non-ICU group 18 percent. Factors that correlated with higher mortality were more prevalent in the ICU group: age, male, hospitalization with ARF, organ failure, sepsis, septic IRA, oliguria and need of dialysis. Overall, the prognostic markers were the same for both the ICU and non-ICU groups. The discrimination with the APACHE II was similar in both, ICU and non-ICU groups and calibration was better in the non-ICU group. The ATN-ISS achieved good discrimination in both the ICU and non-ICU groups, but, regarding calibration, there was a discreet over estimating of mortality in the non-ICU group. The ATN-ISS showed a greater capacity for discrimination than the APACHE II in both the ICU and non-ICU groups. CONCLUSION: It was concluded that the APACHE II and ATN-ISS scores could be used for stratification of risk in patients with ARF treated outside of the ICU in Brazil.