Objetivo: Desarrollar una metodología para evaluar el nivel de protección respiratoria de respiradores, mascarillas quirúrgicas y mascarillas comunitarias que usa la población peruana, usando partículas de un tamaño similar a las que contienen al virus activo del SARS-CoV-2. Materiales y métodos: Se ha determinado una relación lineal directa entre el logaritmo de la concentración de partículas suspendidas en aire y el tiempo transcurrido; por lo cual es posible comparar la cantidad de partículas internas y externas a la mascarilla o respirador en un mismo periodo y conocer el porcentaje de protección respiratoria de cada muestra evaluada. Resultados: Se ha logrado implementar una metodología para evaluar el nivel de protección respiratoria ante aerosoles menores a 5,0 μm. Asimismo, el empleo de accesorios como ligas o ajustadores detrás de cabeza y nuca, y el uso de clips nasales robustos, incrementan significativamente el nivel de protección respiratoria ante partículas con alta probabilidad de contener al SARS-CoV-2. Conclusiones: Se observa una concordancia entre los valores de protección respiratoria obtenidos y los esperados, considerando el nivel de filtración del material empleado de cada mascarilla quirúrgica o respirador, y su nivel de ajuste. Se observó un incremento significativo en los niveles de protección respiratoria.

No abstract

Peru is one of the countries with the highest lead contamination in the world. Biological monitoring has limitations due to the shortage of laboratories with validated methodologies for the measurement of blood lead, and it is necessary to use alternative methods for its measurement in high-altitude cities. We aimed to compare the blood lead levels (BLL) measured by the LeadCare II (LC) method and Graphite Furnace Atomic Absorption Spectrometry (GF-AAS). We measured the BLL of 108 children from the city of La Oroya. The mean and median BLL for GF-AAS were 10.77 ± 4.18 and 10.44 µg/dL, respectively; for the LC method, the mean was 11.71 ± 4.28 and the median was 11.60 µg/dL. We found a positive linear correlation (Rho = 0.923) between both methods. Notwithstanding, the Wilcoxon test suggests a significant difference between both methods (ρ = 0.000). In addition, the Bland–Altman analysis indicates that there is a positive bias (0.94) in the LC method, and this method tends to overestimate the BLL. Likewise, we performed a generalized linear model to evaluate the influence of age and hemoglobin on BLL. We found that age and hemoglobin had a significant influence on BLL measured by the LC method. Finally, we used two non-parametric linear regression methods (Deming and Passing-Bablok regression) to compare the LC method with the GF-AAS. We found that these methods differ by at least a constant amount, and there would be a proportional difference between both. Although in general there is a positive linear correlation, the results of both methods differ significantly. Therefore, its use in cities located at high altitudes (higher than 2440 m.a.s.l.) would not be recommended.

Background: Sputum smear microscopy (SSM) is a screening test used to diagnose tuberculosis (TB); however, its performance and sensitivity are relatively low, which can lead to false negatives. We designed a cross-sectional study to estimate the performance of SSM that includes a pretreatment based on sputum digestion with bleach (sodium hypochlorite) for the diagnosis of TB. Methods: We evaluated 73 sputum samples from patients with a diagnosis of TB confirmed by the Xpert MTB/RIF test and 114 samples from patients without TB. We performed sputum digestion using a 5% sodium hypochlorite solution, centrifuged at 2000 rpm for 15 min. We prepared smears for direct and bleach-treated SSM and used Ziehl–Neelsen staining. Results: The bleach-treated SSM obtained absolute identification of the cases of TB confirmed by the Xpert test, compared to 95.9% identified by the direct smear method (without bleach treatment). We also found a significant increase (p < 0.001) in the recovery of acid-fast bacilli (AFB) obtained by the bleach-treated SSM (293.8 ± 215.1 AFB) compared to the direct SSM method (222.9 ± 195.5 AFB). The AUC of the bleach-treated SSM and direct SSM was 100% and 96.6%, respectively. Conclusion: The bleach-treated SSM performs better than the direct SSM in identifying AFB and increasing the bacillary count in the sputum samples.

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