Impacts of a fraction of inspired oxygen adjustment protocol in COVID-19 patients under mechanical ventilation: A prospective cohort study / Impactos de un protocolo de ajuste de la fracción de oxígeno inspirado en pacientes con COVID-19 sometidos a ventilación mecánica: un estudio de cohorte prospectivo

Objective We examined weather a protocol for fraction of inspired oxygen (FiO2) adjustment can reduce hyperoxemia and excess oxygen use in COVID-19 patients mechanically ventilated. Design Prospective cohort study. Settin Two intensive care units (ICUs) dedicated to COVID-19 patients in Brazil. Patients Consecutive patients with COVID-19 mechanically ventilated. Interventions One ICU followed a FiO2 adjustment protocol based on SpO2 (conservative-oxygen ICU) and the other, which did not follow the protocol, constituted the control ICU. Main variables of interest Prevalence of hyperoxemia (PaO2>100mmHg) on day 1, sustained hyperoxemia (present on days 1 and 2), and excess oxygen use (FiO2>0.6 in patients with hyperoxemia) were compared between the two ICUs. Results Eighty two patients from the conservative-oxygen ICU and 145 from the control ICU were included. The conservative-oxygen ICU presented lower prevalence of hyperoxemia on day 1 (40.2% vs. 75.9%, p<0.001) and of sustained hyperoxemia (12.2% vs. 49.6%, p<0.001). Excess oxygen use was less frequent in the conservative-oxygen ICU on day 1 (18.3% vs. 52.4%, p<0.001). Being admitted in the control ICU was independently associated with hyperoxemia and excess oxygen use. Multivariable analyses found no independent relationship between day 1 hyperoxemia, sustained hyperoxemia, or excess FiO2 use and adverse clinical outcomes. Conclusions Following FiO2 protocol was associated with lower hyperoxemia and less excess oxygen use. Although those results were not associated with better clinical outcomes, adopting FiO2 protocol may be useful in a scenario of depleted oxygen resources, as was seen during the COVID-19 pandemic (AU)

Objetivo Evaluar si un protocolo para el ajuste de la FiO2 reduce la hiperoxemia y el uso excesivo de oxígeno en pacientes con COVID-19 en ventilación mecánica. Diseño Estudio de cohorte prospectivo. Ámbito Unidades de cuidados intensivos (UCI) dedicadas a pacientes con COVID-19 en Brasil. Pacientes Pacientes con COVID-19. Intervenciones Una UCI siguió un protocolo de ajuste de FiO2 basado en SpO2 (UCI de oxigenoterapia conservadora, N=82) y la otra no siguió el protocolo (UCI control, N=145). Principales variables de interés Prevalencia de hiperoxemia (PaO2>100mmHg) en el día 1, hiperoxemia sostenida (presente en los días 1 y 2) y exceso de uso de oxígeno (FiO2>0,6 en pacientes con hiperoxemia) entre las 2 UCI. Resultados La UCI de oxigenoterapia conservadora presentó menor prevalencia de hiperoxemia en el día 1 (40,2 vs. 75,9%; p<0,001) y de hiperoxemia sostenida (12,2 vs. 49,6%; p<0,001). El uso excesivo de oxígeno fue menos frecuente en la UCI de oxigenoterapia conservadora el día 1 (18,3 vs. 52,4%; p<0,001). El ingreso en la UCI control se asoció de forma independiente con la hiperoxemia y el uso excesivo de oxígeno. Los análisis multivariables no encontraron una relación independiente entre hiperoxemia o uso excesivo de FiO2 y resultados clínicos adversos. Conclusiones Seguir el protocolo de FiO2 se asoció con menor hiperoxemia y menor consumo de oxígeno en exceso. Aunque esos resultados no se asociaron con mejores resultados clínicos, la adopción del protocolo FiO2 puede ser útil en un escenario de recursos de oxígeno agotados, como se vio durante la pandemia de COVID-19 (AU)

Impacts of a fraction of inspired oxygen adjustment protocol in COVID-19 patients under mechanical ventilation: A prospective cohort study.

Objective: We examined weather a protocol for fraction of inspired oxygen (FiO2) adjustment can reduce hyperoxemia and excess oxygen use in COVID-19 patients mechanically ventilated. Design: Prospective cohort study. Setting: Two intensive care units (ICUs) dedicated to COVID-19 patients in Brazil. Patients: Consecutive patients with COVID-19 mechanically ventilated. Interventions: One ICU followed a FiO2 adjustment protocol based on SpO2 (conservative-oxygen ICU) and the other, which did not follow the protocol, constituted the control ICU. Main variables of interest: Prevalence of hyperoxemia (PaO2 >100 mmHg) on day 1, sustained hyperoxemia (present on days 1 and 2), and excess oxygen use (FiO2 > 0.6 in patients with hyperoxemia) were compared between the two ICUs. Results: Eighty two patients from the conservative-oxygen ICU and 145 from the control ICU were included. The conservative-oxygen ICU presented lower prevalence of hyperoxemia on day 1 (40.2% vs. 75.9%, p < 0.001) and of sustained hyperoxemia (12.2% vs. 49.6%, p < 0.001). Excess oxygen use was less frequent in the conservative-oxygen ICU on day 1 (18.3% vs. 52.4%, p < 0.001). Being admitted in the control ICU was independently associated with hyperoxemia and excess oxygen use. Multivariable analyses found no independent relationship between day 1 hyperoxemia, sustained hyperoxemia, or excess FiO2 use and adverse clinical outcomes. Conclusions: Following FiO2 protocol was associated with lower hyperoxemia and less excess oxygen use. Although those results were not associated with better clinical outcomes, adopting FiO2 protocol may be useful in a scenario of depleted oxygen resources, as was seen during the COVID-19 pandemic.

Objetivo: Evaluar si un protocolo para el ajuste de la FiO2 reduce la hiperoxemia y el uso excesivo de oxígeno en pacientes con COVID-19 en ventilación mecánica. Diseño: Estudio de cohorte prospectivo. Ámbito: Unidades de cuidados intensivos (UCI) dedicadas a pacientes con COVID-19 en Brasil. Pacientes: Pacientes con COVID-19. Intervenciones: Una UCI siguió un protocolo de ajuste de FiO2 basado en SpO2 (UCI de oxigenoterapia conservadora, N = 82) y la otra no siguió el protocolo (UCI control, N = 145). Principales variables de interés: Prevalencia de hiperoxemia (PaO2 > 100 mmHg) en el día 1, hiperoxemia sostenida (presente en los días 1 y 2) y exceso de uso de oxígeno (FiO2 > 0,6 en pacientes con hiperoxemia) entre las 2 UCI. Resultados: La UCI de oxigenoterapia conservadora presentó menor prevalencia de hiperoxemia en el día 1 (40,2 vs. 75,9%; p < 0,001) y de hiperoxemia sostenida (12,2 vs. 49,6%; p < 0,001). El uso excesivo de oxígeno fue menos frecuente en la UCI de oxigenoterapia conservadora el día 1 (18,3 vs. 52,4%; p < 0,001). El ingreso en la UCI control se asoció de forma independiente con la hiperoxemia y el uso excesivo de oxígeno. Los análisis multivariables no encontraron una relación independiente entre hiperoxemia o uso excesivo de FiO2 y resultados clínicos adversos. Conclusiones: Seguir el protocolo de FiO2 se asoció con menor hiperoxemia y menor consumo de oxígeno en exceso. Aunque esos resultados no se asociaron con mejores resultados clínicos, la adopción del protocolo FiO2 puede ser útil en un escenario de recursos de oxígeno agotados, como se vio durante la pandemia de COVID-19.

Impacts of a fraction of inspired oxygen adjustment protocol in COVID-19 patients under mechanical ventilation: A prospective cohort study.

OBJECTIVE: We examined weather a protocol for fraction of inspired oxygen (FiO2) adjustment can reduce hyperoxemia and excess oxygen use in COVID-19 patients mechanically ventilated. DESIGN: Prospective cohort study. SETTING: Two intensive care units (ICUs) dedicated to COVID-19 patients in Brazil. PATIENTS: Consecutive patients with COVID-19 mechanically ventilated. INTERVENTIONS: One ICU followed a FiO2 adjustment protocol based on SpO2 (conservative-oxygen ICU) and the other, which did not follow the protocol, constituted the control ICU. MAIN VARIABLES OF INTEREST: Prevalence of hyperoxemia (PaO2>100mmHg) on day 1, sustained hyperoxemia (present on days 1 and 2), and excess oxygen use (FiO2>0.6 in patients with hyperoxemia) were compared between the two ICUs. RESULTS: Eighty two patients from the conservative-oxygen ICU and 145 from the control ICU were included. The conservative-oxygen ICU presented lower prevalence of hyperoxemia on day 1 (40.2% vs. 75.9%, p<0.001) and of sustained hyperoxemia (12.2% vs. 49.6%, p<0.001). Excess oxygen use was less frequent in the conservative-oxygen ICU on day 1 (18.3% vs. 52.4%, p<0.001). Being admitted in the control ICU was independently associated with hyperoxemia and excess oxygen use. Multivariable analyses found no independent relationship between day 1 hyperoxemia, sustained hyperoxemia, or excess FiO2 use and adverse clinical outcomes. CONCLUSIONS: Following FiO2 protocol was associated with lower hyperoxemia and less excess oxygen use. Although those results were not associated with better clinical outcomes, adopting FiO2 protocol may be useful in a scenario of depleted oxygen resources, as was seen during the COVID-19 pandemic.

Screening stress factors survey in an institute of advanced studies: health and safety integrated plans.

The current paper presents the study of organizational stressors survey carried out in a military institute, responsible for researches of high demand on aerospace technology. The study considered the theoretical framework of Organizational Ergonomics, combined with the technical guidelines of Psychology applied to Work Safety. The participatory approach was used on daily work assessment and decision making, aiming the adoption of corrective and preventive measures, considering possible distortions and imbalances between prescribed and actual activities. Thus, it was sought to engage and encourage the participation of the Institute's workers in the reflection/creation of better solutions to daily problems and to achieve productivity, without prejudice in the occupational health and safety.

On the use of classic epidemiological formulae for estimating the intensity of endemic malaria transmission by vectors in the Amazon.

Although various reports have described entomological inoculation rates of malaria vector species, most were limited to providing descriptive field data. Here, we report biting rates and survival data for two important malaria vectors in the Amazon, Anopheles darlingi (Root) and Anopheles albitarsis E (Lynch-Arribalzaga) (Diptera: Culicidae), in the state of Roraima, Brazil. We calculated theoretical sporozoite infection rates and critical vector biting rates for these species during 1 year, comprising six bimestrial collections. Anopheles darlingi had higher sporozoite rates and lower critical biting rates, indicating that it would be the more efficient vector at the beginning of epidemic malaria transmission. Our data, together with compiled information from the literature in the Amazon, suggest that epidemic malaria transmission may be initiated by the primary vector, such as A. darlingi, while secondary vectors, such as A. albitarsis E, may only become epidemiologically important when there is an increase in the prevalence of human malaria. We propose that mathematical modeling may be able to quantify the relative importance of secondary vector species in malaria epidemiology.

Spatial clustering and longitudinal variation of Anopheles darlingi (Diptera: Culicidae) larvae in a river of the Amazon: the importance of the forest fringe and of obstructions to flow in frontier malaria.

Deforestation has been linked to a rise in malaria prevalence. In this paper, we studied longitudinally 20 spots, including forested and deforested portions of a temporary river in a malarigenous frontier zone. Larval habitat parameters influencing distribution of Anopheles darlingi (Diptera: Culicidae) larvae were studied. We observed that larvae were clustered in forested-deforested transitions. For the first time in the literature, it was verified that parameters determining larval distribution varied from deforested to forested areas. The proximity to human dwellings was also a significant factor determining distribution, but larvae was most importantly associated with a previously undescribed parameter, the presence of small obstructions to river flow, such as tree trunks within the river channel, which caused pooling of water during the dry season ('microdams'). In deforested areas, the most important factor determining distribution of larvae was shade (reduced luminance). Larvae were absent in the entire studied area during the wet season and present in most sites during the dry season. During the wet-dry transition, larvae were found sooner in areas with microdams, than in other areas, suggesting that flow obstruction prolongs the breeding season of An. darlingi. Adult mosquito densities and malaria incidence were higher during the dry season. Our data correlate well with the published literature, including the distribution of malaria cases near the forest fringes, and has permitted the creation of a model of An. darlingi breeding, where preference for sites with reduced luminance, human presence and microdams would interact to determine larval distribution.

The HIV epidemic in the Amazon Basin is driven by prototypic and recombinant HIV-1 subtypes B and F.

This paper describes genetic subtypes of HIV-1 found in blood samples from 31 HIV-1-infected people who visited the Counseling and Testing AIDS Center of Instituto de Medicina Tropical in Manaus, Brazil. Manaus, the main city in Brazil's Amazon Basin, is also the closest urban connection for more than 100,000 Indians living in the rain forests of this region. Although to date there is no evidence of increased incidence of HIV-1 infection among the indigenous population, our understanding of both the prevalence and nature of the epidemic in the region as a whole is limited. From the 31 samples analyzed by C2V3 sequencing, we found almost equal proportions of HIV-1 strains belonging to subtype B (n = 16; 51.6%) and subtype F (n = 15; 48.4%), a finding that differs from results from previous studies conducted in urban areas of southeastern Brazil. We also observed the presence of the GWGR amino-acid sequence in the critical tetra-peptide crown of the env V3 loop in the HIV-1 subtype B samples analyzed. Among these samples, we also found 14 mosaic genomes (45.16%) in which different combinations of subtypes B, C, and F were identified between the p24 gag, pro, and env regions. Our data support the hypothesis that the Amazonian HIV-1 infections linked to the urban epidemic in southeastern Brazil. The genetic diversity and the prevalence of mosaic genomes among the isolates in our study confirm an integral role of recombination in the complex Brazilian epidemic.

Ectonucleotide diphosphohydrolase activities in Entamoeba histolytica.

In this work, we describe the ability of living cells of Entamoeba histolytica to hydrolyze extracellular ATP. In these intact parasites, whose viability was determined by motility and by the eosin method, ATP hydrolysis was low in the absence of any divalent metal (78 nmol P(i)/h/10(5) cells). Interestingly, in the presence of 5 mM MgCl(2) an ecto-ATPase activity of 300 nmol P(i)/h/10(5) cells was observed. The addition of MgCl(2) to the extracellular medium increased the ecto-ATPase activity in a dose-dependent manner. At 5 mM ATP, half-maximal stimulation of ATP hydrolysis was obtained with 1.23 mM MgCl(2). Both activities were linear with cell density and with time for at least 1 h. The ecto-ATPase activity was also stimulated by MnCl(2) and CaCl(2) but not by SrCl(2), ZnCl(2), or FeCl(3). In fact, FeCl(3) inhibited both Mg(2+)-dependent and Mg(2+)-independent ecto-ATPase activities. The Mg(2+)-independent ATPase activity was unaffected by pH in the range between 6.4 and 8. 4, in which the cells were viable. However, the Mg(2+)-dependent ATPase activity was enhanced concomitantly with the increase in pH. In order to discard the possibility that the ATP hydrolysis observed was due to phosphatase or 5'-nucleotidase activities, several inhibitors for these enzymes were tested. Sodium orthovanadate, sodium fluoride, levamizole, and ammonium molybdate had no effect on the ATPase activities. In the absence of Mg(2+) (basal activity), the apparent K(m) for ATP(4-) was 0.053 +/- 0.008 mM, whereas at saturating MgCl(2) concentrations, the corresponding apparent K(m) for Mg-ATP(2-) for Mg(2+)-dependent ecto-ATPase activity (difference between total and basal ecto-ATPase activity) was 0.503 mM +/- 0.062. Both ecto-ATPase activities were highly specific for ATP and were also able to hydrolyze ADP less efficiently. To identify the observed hydrolytic activities as those of an ecto-ATPase, we used suramin, a competitive antagonist of P(2) purinoreceptors and an inhibitor of some ecto-ATPases, as well as the impermeant agent 4'-4'-diisothiocyanostylbenzene-2'-2'-disulfonic acid. These two reagents inhibited the Mg(2+)-independent and the Mg(2+)-dependent ATPase activities to different extents, and the inhibition by both agents was prevented by ATP. A comparison among the ecto-ATPase activities of three amoeba species showed that the noninvasive E. histolytica and the free-living E. moshkovskii were less efficient than the pathogenic E. histolytica in hydrolyzing ATP. As E. histolytica is known to have a galactose-specific lectin on its surface, which is related to the pathogenesis of amebiasis, galactose was tested for an effect on ecto-ATPase activities. It stimulated the Mg(2+)-dependent ecto-ATPase but not the Mg(2+)-independent ATPase activity.

Cellulose acetate as solid phase in ELISA for plague.

Antigen from Yersinia pestis was adsorbed on cellulose acetate discs (0.5 cm of diameter) which were obtained from dialysis membrane by using a paper punch. ELISA for human plague diagnosis was carried out employing this matrix and was capable to detect amount of 1.3 microg of antigen, 3,200 times diluted positive serum using human anti-IgG conjugate diluted 1:4,000. No relevant antigen lixiviation from the cellulose acetate was observed even after washing the discs 15 times. The discs were impregnated by the coloured products from the ELISA development allowing its use in dot-ELISA. Furthermore, cellulose acetate showed a better performance than the conventional PVC plates.

Cellulose acetate as solid phase in ELISA for plague

Antigen from Yersinia pestis was adsorbed on cellulose acetate discs (0.5 cm of diameter) which were obtained from dialysis membrane by using a paper punch. ELISA for human plague diagnosis was carried out employing this matrix and was capable to detect amount of 1.3 µg of antigen, 3,200 times diluted positive serum using human anti-IgG conjugate diluted 1:4,000. No relevant antigen lixiviation from the cellulose acetate was observed even after washing the discs 15 times. The discs were impregnated by the coloured products from the ELISA development allowing its use in dot-ELISA. Furthermore, cellulose acetate showed a better performance than the conventional PVC plates.

Platelet-activating factor induction of secreted phosphatase activity in Trypanosoma cruzi.

The effects of platelet-activating factor (PAF) on the ecto-phosphatase activity of Trypanosoma cruzi were investigated. Living parasites hydrolyzed p-nitrophenyl phosphate (p-NPP) at a rate of 5.71 +/- 0.37 nmol P(i) mg(-1) min(-1). This ecto-phosphatase activity increased to 8.70 +/- 1.12 nmol P(i) mg(-1) min(-1) when the cells were grown in the presence of 10(-9) M PAF. This effect was probably due to stimulation of the release of the ecto-phosphatase and/or the secretion of an intracellular phosphatase to the extracellular medium, as suggested by cytochemical analysis. Modulation of the ecto-phosphatase activity was also observed when PAF was added during the time course of the reaction. WEB 2086, a competitive PAF antagonist, was able to revert PAF effects when both were used at the same concentration. When PAF was added to a membrane enriched fraction preparation of T. cruzi, no alteration on the phosphatase activity was observed. This result suggests an involvement of intracellular signaling, as PAF was only effective on intact cells. Sphingosine and phorbol-12-myristate-13-acetate (PMA) were then used to investigate a possible involvement of protein kinase C (PKC) with PAF-induced phosphatase secretion. Sphingosine by itself stimulated the secretion of a phosphatase but did not significantly interfere with PAF effects on this enzyme. On the other hand, PMA was able to abrogate PAF-induced release of this phosphatase. These data are highly suggestive of a putative involvement of signal transduction mediated by a ligand of mammalian origin (PAF), through PKC and a specific receptor located on the cell surface of the human parasite Trypanosoma cruzi.

Diameter-reflux relationship in perforating veins of patients with varicose veins.

PURPOSE: Treatment of chronic venous valvular insufficiency requires understanding of the hemodynamics of perforating veins. To preserve normal veins or veins that can function normally once primary sources of valvular insufficiency are removed, a better understanding of the diameter-reflux relationship is desirable. We measured reflux and diameters in 500 perforating veins of patients with varicose veins (C(2)E(P)A(SP)P(R)). METHODS: Color flow duplex ultrasonography scanning was performed with the patient standing. Perforating veins were mapped medially in the thigh and medially, laterally, and posteriorly in the calf. Reflux was defined as reverse flow that lasted longer than 0.5 seconds. Diameters were measured on B-mode transverse projections at the crossing of the fascia. Competent versus incompetent vein diameters were compared by means of Student t test, one-way analysis of variance, and Bonferroni t test. RESULTS: Diameters of competent and incompetent perforators averaged 2.5 +/- 0.9 mm (n = 17) and 4.7 +/- 1.9 mm (n = 17) at the medial thigh (P <.0002), 2.2 +/- 0.8 mm (n = 179) and 3.7 +/- 1.0 mm (n = 210) at the medial calf (P <.0001), 2.2 +/- 0.6 mm (n = 13) and 3.5 +/- 0.8 mm (n = 37) at the posterior calf (P <. 0001), and 2.1 +/- 0.8 mm (n = 9) and 3.3 +/- 0.7 mm (n = 18) at the lateral calf (P <.003), respectively. Perforating vein diameters of 3.5 mm or larger in the calf and thigh were associated with reflux in more than 90% of the cases. CONCLUSION: An enlargement in the diameter of the perforating veins of 1 to 1.5 mm in the calf or 2 mm in the thigh of patients with varicose veins could be the difference between normal flow and reflux. Further studies are needed to confirm if elimination of reflux in patients with primary varicosity will transform incompetent perforators to competent ones.