Effect of High-Flow Oxygen Therapy vs Conventional Oxygen Therapy on Invasive Mechanical Ventilation and Clinical Recovery in Patients With Severe COVID-19: A Randomized Clinical Trial.

IMPORTANCE: The effect of high-flow oxygen therapy vs conventional oxygen therapy has not been established in the setting of severe COVID-19. OBJECTIVE: To determine the effect of high-flow oxygen therapy through a nasal cannula compared with conventional oxygen therapy on need for endotracheal intubation and clinical recovery in severe COVID-19. DESIGN, SETTING, AND PARTICIPANTS: Randomized, open-label clinical trial conducted in emergency and intensive care units in 3 hospitals in Colombia. A total of 220 adults with respiratory distress and a ratio of partial pressure of arterial oxygen to fraction of inspired oxygen of less than 200 due to COVID-19 were randomized from August 2020 to January 2021, with last follow-up on February 10, 2021. INTERVENTIONS: Patients were randomly assigned to receive high-flow oxygen through a nasal cannula (n = 109) or conventional oxygen therapy (n = 111). MAIN OUTCOMES AND MEASURES: The co-primary outcomes were need for intubation and time to clinical recovery until day 28 as assessed by a 7-category ordinal scale (range, 1-7, with higher scores indicating a worse condition). Effects of treatments were calculated with a Cox proportional hazards model adjusted for hypoxemia severity, age, and comorbidities. RESULTS: Among 220 randomized patients, 199 were included in the analysis (median age, 60 years; n = 65 women [32.7%]). Intubation occurred in 34 (34.3%) randomized to high-flow oxygen therapy and in 51 (51.0%) randomized to conventional oxygen therapy (hazard ratio, 0.62; 95% CI, 0.39-0.96; P = .03). The median time to clinical recovery within 28 days was 11 (IQR, 9-14) days in patients randomized to high-flow oxygen therapy vs 14 (IQR, 11-19) days in those randomized to conventional oxygen therapy (hazard ratio, 1.39; 95% CI, 1.00-1.92; P = .047). Suspected bacterial pneumonia occurred in 13 patients (13.1%) randomized to high-flow oxygen and in 17 (17.0%) of those randomized to conventional oxygen therapy, while bacteremia was detected in 7 (7.1%) vs 11 (11.0%), respectively. CONCLUSIONS AND RELEVANCE: Among patients with severe COVID-19, use of high-flow oxygen through a nasal cannula significantly decreased need for mechanical ventilation support and time to clinical recovery compared with conventional low-flow oxygen therapy. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT04609462.

Spatial and temporal population dynamics of male and female Aedes albopictus at a local scale in Medellín, Colombia.

BACKGROUND: Diseases transmitted by invasive Aedes aegypti and Aedes albopictus mosquitoes are public health issues in the tropics and subtropics. Understanding the ecology of mosquito vectors is essential for the development of effective disease mitigation programs and will allow for accurate predictions of vector occurrence and abundance. Studies that examine mosquito population dynamics are typically focused on female presence or total adult captures without discriminating the temporal and spatial distribution of both sexes. METHODS: We collected immature and adult mosquitoes bimonthly for 2 years (2018-2019) in the Medellín Botanical Garden. Collection sites differed in proximity to buildings and nearby vegetation, and were classified by their overhead vegetation cover. We used linear mixed models (LMMs) and Spatial Analysis by Distance Indices (SADIE) to assess the spatial distribution of Ae. aegypti and Ae. albopictus. Using our Ae. albopictus captures exclusively, we assessed (1) the spatial and temporal distribution of males and females using SADIE and a generalized linear mixed model (GLMM), (2) the relationship between climatic variables/vegetation coverage and adult captures using GLMMs and LMMs, and (3) the correlation of male and female size in relation to climatic variables and vegetation coverage using LMMs. RESULTS: Spatial analysis showed that Ae. aegypti and Ae. albopictus were distributed at different locations within the surveilled area. However, Ae. albopictus was the predominant species in the park during the study period. Adult Ae. albopictus captures were positively correlated with precipitation and relative humidity, and inversely correlated with temperature and wind speed. Moreover, we observed a spatial misalignment of Ae. albopictus males and females-the majority of males were located in the high vegetation coverage sites, while females were more evenly distributed. We observed significant associations of the size of our adult Ae. albopictus captures with precipitation, temperature, and wind speed for both sexes and found that overhead vegetation cover influenced male size, but observed no effect on female size. CONCLUSIONS: Our work elucidates the differential dynamics of Ae. albopictus males and females, which is pivotal to develop accurate surveillance and the successful establishment of vector control programs based on the disruption of insect reproduction.

Consideraciones anestésicas en el paciente con enfermedad por virus dengue / Anesthetic considerations in the patient with dengue virus disease

El dengue continúa siendo un problema de salud pública en América. Suele presentarse como una enfermedad febril leve, sin embargo, los pacientes con enfermedad grave pueden presentar síndromes hemorrágicos y choque por dengue. Diferentes circunstancias pueden surgir en el curso evolutivo de los pacientes con dengue impactando en la posibilidad de que sea necesario realizar en ellos una intervención quirúrgica, ante lo cual es necesario plantear las consideraciones anestésicas que deben ser tenidas en cuenta para el correcto abordaje. El presente texto tiene como objetivo establecer consideraciones clínicas útiles para el manejo anestésico en el paciente con enfermedad por dengue para reducir el riesgo de complicaciones peri-operatorias y muerte.

Dengue fever continues to be a public health problem in America. It usually presents as a mild febrile illness, however, patients with severe disease may have hemorrhagic syndromes and dengue shock. Different circumstances can arise in the evolutionary course of patients with dengue impacting on the possibility that it is necessary to perform a surgical intervention, before which it is necessary to raise the anesthetic considerations that must be taken into account for the correct approach. The present text aims to establish useful clinical considerations for anesthetic management in the patient with dengue disease to reduce the risk of peri-operative complications and death.

Vector Transmission Alone Fails to Explain the Potato Yellow Vein Virus Epidemic among Potato Crops in Colombia.

The potato yellow vein disease, caused by the potato yellow vein virus (PYVV), is a limiting potato disease in northern South America. The virus can be transmitted either by the greenhouse whitefly (GWF), Trialeurodes vaporariorum (Westwood) (Hemiptera: Aleyrodidae), or through vegetative propagules, such as infected tubers. Recently, GWF populations have been spotlighted as one of the main drivers of PYVV re-emergence, and consequently, PYVV management has been predominantly directed toward vector control, which is heavily based on insecticide use. However, the drivers of the PYVV outbreaks as well as the contribution of GWF populations on the spread of PYVV among potato crops are still not completely understood. This study aims to assess the role of the GWF as a driver of the PYVV epidemic in the potato-producing areas in Colombia, one of the countries more severely affected by the PYVV epidemic, and whose geography allows the study of the spatial association between the vector and the disease epidemic across a wide altitude range. The geographical clusters where the PYVV epidemic is concentrated, as well as those of farms affected by the GWF were identified using a novel spatial epidemiology approach. The influence of altitude range on the association between PYVV and T. vaporarioum was also assessed. We found a relatively poor spatial association between PYVV epidemic and the presence of the GWF, especially at altitudes above 3,000 m above mean sea level. Furthermore, GWF populations could only explain a small fraction of the extent of the PYVV epidemic in Colombia. Movement of infected seed tubers might be the main mechanism of dispersion, and could be a key driver for the PYVV infection among potato crops. Agricultural policies focused on improving quality of seed tubers and their appropriate distribution could be the most efficient control intervention against PYVV dispersion.

Detection of Ptaquilosides in different phenologic stages of Bracken fern (Pteridium aquilinum) and analysis of mik samples in farms with hematuria in Tolima, Colombia / Detección de ptaquilósido en diferentes estados fenológicos de "helecho macho" (Pteridium aquilinum) y análisis de muestras de leche en granjas con hematuria en Tolima, Colombia / Detecção da ptaquilosida em diferentes estágios fenológicos da samambaia (Pteridiumaquilinum) e análise de amostras de leite em fazendas com hematúria em Tolima, Colômbia

Bracken fern or "Helecho Macho" (Pteridium aquilinum) is one of the most common weeds in the meadows of the mountain ranges of Colombia. Consumption of this palatable plant by bovines causes a disease known as bovine enzootic hematuria and esophageal neoplasia. The toxic effect of the plant in bovines is caused by the ptaquiloside, main carcinogenic toxin of this plant. In this study, eight samples of Bracken fern in different phenologic stages and 16 milk samples collected in two towns of Tolima, Líbano and Murillo, were analized. In both cases, Highperformance liquid cromatography (HPLC) coupled with Mass Spectrometry (MS) was used. In all Bracken fern samples analized, detectable levels of ptaquilosides were observed, ranging from 23 to 1194 µg/g, with a 342 µg/g mean. No detectable levels of ptaquilosides were found in the milk samples. The results show a great variation in the content of ptaquilosides depending on the phenologic stage and collection site of the plant. It is posible that the reported instability of the ptaquiloside and the processing given to the milk samples could have caused the lack of detection of the compound in milk

El "helecho macho" (Pteridium aquilinum) es una de las malezas más comunes en praderas de la región de cordillera en Colombia. El consumo de esta planta palatable por parte de los bovinos causa una enfermedad conocida como hematuria enzoótica bovina y neoplasias de esófago. El efecto tóxico de la planta en los bovinos es causado por el ptaquilósido, principal toxina carcinogénica de esta planta. En el presente estudio se analizaron ocho muestras en diferentes estados fenológicos del helecho obtenidas en dos municipios del departamento del Tolima (Líbano y Murillo) y 16 muestras de leche de la misma zona. En ambos casos se utilizó como técnica analítica cromatografía líquida de alta eficiencia (HPLC) acoplada a espectrometría de masas (MS). En todas las muestras analizadas se observaron niveles detectables de ptaquilósido, con un rango de 23 a 1.194 µg/g y un promedio de 342 µg/g. No se encontraron niveles detectables de ptaquilósido en ninguna de las muestras de leche. Los resultados del estudio muestran la gran variación en el contenido de ptaquilósido dependiendo del estado fenológico de la planta y del sitio de colecta. Es posible que la reportada inestabilidad del ptaquilósido y el tipo de procesamiento dado a las muestras de leche haya ocasionado la no detección del compuesto en las mismas.

A samambaia (Pteridium aquilinum) é uma das ervas daninhas mais comuns nas pastagens na região de cordilheira na Colômbia. O consumo desta planta palatável para os bovinos, causa uma doença conhecida como hematúria enzoótica bovina e neoplasias de esôfago. O efeito tóxico da planta nos bovinos é causado pelo ptaquilosídeo, principal toxina carcinogênica desta planta. No presente estudo foram analisadas oito amostras em diferentes estágios fenológicos da samambaia e 16 amostras de leite obtidas em dois municípios do departamento de Tolima (Líbano e Murillo). Em ambos os casos foi utilizada como técnica analítica a cromatografia líquida de alta eficiência (HPLC) acoplada a espectrometria de massas (MS). Em todas as amostras analisadas foram observados níveis detectáveis de ptaquilosídeo, com um rango de 23 a 1.194 µg/g e uma média de 342 µg/g. Não foram encontrados níveis detectáveis de ptaquilosídeo em nenhuma das amostras de leite. Os resultados do estudo mostram a grande variação no conteúdo de ptaquilosídeo dependendo do estágio fenológico da planta e do local da coleta. É possível que a reportada instabilidade do ptaquilosídeo e o tipo de processamento dado às amostras de leite seja a causa da falta de detecção do composto nas amostras de leite analisadas.

Can venous-to-arterial carbon dioxide differences reflect microcirculatory alterations in patients with septic shock?

PURPOSE: Septic shock has been associated with microvascular alterations and these in turn with the development of organ dysfunction. Despite advances in video microscopic techniques, evaluation of microcirculation at the bedside is still limited. Venous-to-arterial carbon dioxide difference (Pv-aCO2) may be increased even when venous O2 saturation (SvO2) and cardiac output look normal, which could suggests microvascular derangements. We sought to evaluate whether Pv-aCO2 can reflect the adequacy of microvascular perfusion during the early stages of resuscitation of septic shock. METHODS: Prospective observational study including 75 patients with septic shock in a 60-bed mixed ICU. Arterial and mixed-venous blood gases and hemodynamic variables were obtained at catheter insertion (T0) and 6 h after (T6). Using a sidestream dark-field device, we simultaneously acquired sublingual microcirculatory images for blinded semiquantitative analysis. Pv-aCO2 was defined as the difference between mixed-venous and arterial CO2 partial pressures. RESULTS: Progressively lower percentages of small perfused vessels (PPV), lower functional capillary density, and higher heterogeneity of microvascular blood flow were observed at higher Pv-aCO2 values at both T0 and T6. Pv-aCO2 was significantly correlated to PPV (T0: coefficient -5.35, 95 % CI -6.41 to -4.29, p < 0.001; T6: coefficient, -3.49, 95 % CI -4.43 to -2.55, p < 0.001) and changes in Pv-aCO2 between T0 and T6 were significantly related to changes in PPV (R (2) = 0.42, p < 0.001). Absolute values and changes in Pv-aCO2 were not related to global hemodynamic variables. Good agreement between venous-to-arterial CO2 and PPV was maintained even after corrections for the Haldane effect. CONCLUSIONS: During early phases of resuscitation of septic shock, Pv-aCO2 could reflect the adequacy of microvascular blood flow.

Generating Within-Plant Spatial Distributions of an Insect Herbivore Based on Aggregation Patterns and Per-Node Infestation Probabilities.

Most predator-prey models extrapolate functional responses from small-scale experiments assuming spatially uniform within-plant predator-prey interactions. However, some predators focus their search in certain plant regions, and herbivores tend to select leaves to balance their nutrient uptake and exposure to plant defenses. Individual-based models that account for heterogeneous within-plant predator-prey interactions can be used to scale-up functional responses, but they would require the generation of explicit prey spatial distributions within-plant architecture models. The silverleaf whitefly, Bemisia tabaci biotype B (Gennadius) (Hemiptera: Aleyrodidae), is a significant pest of tomato crops worldwide that exhibits highly aggregated populations at several spatial scales, including within the plant. As part of an analytical framework to understand predator-silverleaf whitefly interactions, the objective of this research was to develop an algorithm to generate explicit spatial counts of silverleaf whitefly nymphs within tomato plants. The algorithm requires the plant size and the number of silverleaf whitefly individuals to distribute as inputs, and includes models that describe infestation probabilities per leaf nodal position and the aggregation pattern of the silverleaf whitefly within tomato plants and leaves. The output is a simulated number of silverleaf whitefly individuals for each leaf and leaflet on one or more plants. Parameter estimation was performed using nymph counts per leaflet censused from 30 artificially infested tomato plants. Validation revealed a substantial agreement between algorithm outputs and independent data that included the distribution of counts of both eggs and nymphs. This algorithm can be used in simulation models that explore the effect of local heterogeneity on whitefly-predator dynamics.

Combination of arterial lactate levels and venous-arterial CO2 to arterial-venous O 2 content difference ratio as markers of resuscitation in patients with septic shock.

PURPOSE: To evaluate the prognostic value of the Cv-aCO2/Da-vO2 ratio combined with lactate levels during the early phases of resuscitation in septic shock. METHODS: Prospective observational study in a 60-bed mixed ICU. One hundred and thirty-five patients with septic shock were included. The resuscitation protocol targeted mean arterial pressure, pulse pressure variations or central venous pressure, mixed venous oxygen saturation, and lactate levels. Patients were classified into four groups according to lactate levels and Cv-aCO2/Da-vO2 ratio at 6 h of resuscitation (T6): group 1, lactate ≥2.0 mmol/L and Cv-aCO2/Da-vO2 >1.0; group 2, lactate ≥2.0 mmol/L and Cv-aCO2/Da-vO2 ≤1.0; group 3, lactate <2.0 mmol/L and Cv-aCO2/Da-vO2 >1.0; and group 4, lactate <2.0 mmol/L and Cv-aCO2/Da-vO2 ≤1.0. RESULTS: Combination of hyperlactatemia and high Cv-aCO2/Da-vO2 ratio was associated with the worst SOFA scores and lower survival rates at day 28 [log rank (Mantel-Cox) = 31.39, p < 0.0001]. Normalization of both variables was associated with the best outcomes. Patients with a high Cv-aCO2/Da-vO2 ratio and lactate <2.0 mmol/L had similar outcomes to hyperlactatemic patients with low Cv-aCO2/Da-vO2 ratio. The multivariate analysis revealed that Cv-aCO2/Da-vO2 ratio at both T0 (RR 3.85; 95 % CI 1.60-9.27) and T6 (RR 3.97; 95 % CI 1.54-10.24) was an independent predictor for mortality at day 28, as well as lactate levels at T6 (RR 1.58; 95 % CI 1.13-2.22). CONCLUSION: Complementing lactate assessment with Cv-aCO2/Da-vO2 ratio during early stages of resuscitation of septic shock can better identify patients at high risk of adverse outcomes. The Cv-aCO2/Da-vO2 ratio may become a potential resuscitation goal in patients with septic shock.

Persistently high venous-to-arterial carbon dioxide differences during early resuscitation are associated with poor outcomes in septic shock.

INTRODUCTION: Venous-to-arterial carbon dioxide difference (Pv-aCO2) may reflect the adequacy of blood flow during shock states. We sought to test whether the development of Pv-aCO2 during the very early phases of resuscitation is related to multi-organ dysfunction and outcomes in a population of septic shock patients resuscitated targeting the usual oxygen-derived and hemodynamic parameters. METHODS: We conducted a prospective observational study in a 60-bed mixed ICU in a University affiliated Hospital. 85 patients with a new septic shock episode were included. A Pv-aCO2 value ≥ 6 mmHg was considered to be high. Patients were classified in four predefined groups according to the Pv-aCO2 evolution during the first 6 hours of resuscitation: (1) persistently high Pv-aCO2 (high at T0 and T6); (2) increasing Pv-aCO2 (normal at T0, high at T6); (3) decreasing Pv-aCO2 (high at T0, normal at T6); and (4) persistently normal Pv-aCO2 (normal at T0 and T6). Multiorgan dysfunction at day-3 was compared for predefined groups and a Kaplan Meier curve was constructed to show the survival probabilities at day-28 using a log-rank test to evaluate differences between groups. A Spearman-Rho was used to test the agreement between cardiac output and Pv-aCO2. Finally, we calculated the mortality risk ratios at day-28 among patients attaining normal oxygen parameters but with a concomitantly increased Pv-aCO2. RESULTS: Patients with persistently high and increasing Pv-aCO2 at T6 had significant higher SOFA scores at day-3 (p < 0.001) and higher mortality rates at day-28 (log rank test: 19.21, p < 0.001) compared with patients who evolved with normal Pv-aCO2 at T6. Interestingly, a poor agreement between cardiac output and Pv-aCO2 was observed (r2 = 0.025, p < 0.01) at different points of resuscitation. Patients who reached a central venous saturation (ScvO)2 ≥ 70% or mixed venous oxygen saturation (SvO2) ≥ 65% but with concomitantly high Pv-aCO2 at different developmental points (i.e., T0, T6 and T12) had a significant mortality risk ratio at day-28. CONCLUSION: The persistence of high Pv-aCO2 during the early resuscitation of septic shock was associated with more severe multi-organ dysfunction and worse outcomes at day-28. Although mechanisms conducting to increase Pv-aCO2 during septic shock are insufficiently understood, Pv-aCO2 could identify a high risk of death in apparently resuscitated patients.