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.

Adherence to protective mechanical ventilation in COVID-19 versus non-COVID-19-associated acute respiratory distress syndrome: Comparison between two prospective cohorts.

OBJECTIVE: To compare adherence to protective mechanical ventilation (MV) parameters in patients with acute respiratory distress syndrome (ARDS) caused by COVID-19 with patients with ARDS from other etiologies. DESIGN: Multiple prospective cohort study. SETTING: Two Brazilian cohorts of ARDS patients were evaluated. One with COVID-19 patients admitted to two Brazilian intensive care units (ICUs) in 2020 and 2021 (C-ARDS, n=282), the other with ARDS-patients from other etiologies admitted to 37 Brazilian ICUs in 2016 (NC-ARDS, n=120). PATIENTS: ARDS patients under MV. INTERVENTIONS: None. MAIN VARIABLES OF INTEREST: Adherence to protective MV (tidal volume ≤8mL/kg PBW; plateau pressure ≤30cmH2O; and driving pressure ≤15cmH2O), adherence to each individual component of the protective MV, and the association between protective MV and mortality. RESULTS: Adherence to protective MV was higher in C-ARDS than in NC-ARDS patients (65.8% vs. 50.0%, p=0.005), mainly due to a higher adherence to driving pressure ≤15cmH2O (75.0% vs. 62.4%, p=0.02). Multivariable logistic regression showed that the C-ARDS cohort was independently associated with adherence to protective MV. Among the components of the protective MV, only limiting driving pressure was independently associated with lower ICU mortality. CONCLUSIONS: Higher adherence to protective MV in patients with C-ARDS was secondary to higher adherence to limiting driving pressure. Additionally, lower driving pressure was independently associated with lower ICU mortality, which suggests that limiting exposure to driving pressure may improve survival in these patients.

Physical activity in daily life assessed by an accelerometer in kidney transplant recipients and hemodialysis patients.

BACKGROUND: Sedentary lifestyle is a problem among hemodialysis (HD) patients, potentially attenuated after kidney transplantation. However, the effect of kidney transplantation on physical activity has not been thoroughly investigated. OBJECTIVE: This study sought to evaluate the physical activity in daily life in kidney transplant recipients (KTRs) compared with HD patients and to explore its relationship with clinical variables. METHODS: A cross-sectional study enrolled KTRs who received transplants at least 6 months before the study (N = 23; 48.3 ± 10.3 years) and patients undergoing HD for at least 6 months (N = 20; 47.3 ± 12.6 years). Time spent in different activities (walking, standing, sitting, and lying down) and number of steps taken, measured by a multiaxial accelerometer used for 12 h/d on 2 consecutive days for KTRs and on 4 consecutive days for HD patients, were evaluated. RESULTS: KTRs engaged in more active time per day (sum of walking and standing time) than HD patients (311 ± 87 vs 196 ± 54 min/d; P = .001), with longer walking (106 ± 53 vs 70 ± 27 min/d; P = .008) and standing time (205 ± 55 vs 126 ± 42 min/d; P < .001). Sixty-five percent of KTRs were classified as active (>7500 steps/d) compared with only 20% of the HD group (P < .05). The multivariate analysis showed that time posttransplantation was significantly associated with walking time and active time. CONCLUSIONS: By using an accelerometer, a precise method, this study showed that KTRs are significantly more active in daily life than HD patients, and that daily physical activity increases with time since transplantation.

Dielectric behavior of epoxy/BaTiO3 composites using nanostructured ceramic fibers obtained by electrospinning.

Composite materials made of epoxy resin and barium titanate (BT) electrospun nanostructured fibers were prepared. BT fibers were synthesized from a sol based on barium acetate, titanium isopropoxide, and poly(vinyl pyrrolidone). The fibers were heat-treated at different temperatures and characterized by X-ray diffraction, scanning electron microscopy (SEM), and Raman spectroscopy. Mats of BT fibers heat-treated at 800 °C were embedded in epoxy resin into suitable molds. The composites were characterized by SEM, and dielectric measurements were performed by means of dielectric spectroscopy. The dielectric permittivity and dielectric modulus of epoxy resin/BT-fiber composites were measured for two types of samples: with the electrodes parallel and perpendicular to the BT fiber layers. Interestingly, composite samples with electrodes perpendicular to the fiber layers and a BT content as low as 2 vol % led to dielectric permittivities three times higher than that of pure epoxy resin.