Abstract This is a preliminary, multicenter, retrospective cohort study, including 272 consecutive patients with COVID-19 admitted to hospitals in Buenos Aires Province, between May 15th and July 1st, 2020, included in an expanded access program to convalescent plasma. Our objectives were to analyze mortality and its independent risk factors, and to assess the occurrence of a favorable evolution, defined as hospital discharge, or stay at the ward, or transfer from ICU to ward. Patients were stratified into 4 subgroups: admission to the ward with pneumonia and/or oxygen requirement (WARD; n = 100); ICU admission (ICU; n = 87); ICU admission with requirement of mechanical ventilation (ICU-MV; n = 56), and ICU-MV plus septic shock (ICU-MV-SS; N = 29). Mortality at 28 days was 26.1% for the entire group, 14.0% for WARD group, 18.4% for ICU, 44.6% for ICU-MV, and 55.2% for ICU-MV-SS. Mean survival time (days) was 25.6±0.6 (WARD); 25.3±0.7 (ICU); 20.8±1.2 (ICU-MV) and 18.2 ± 1.8 (ICU-MV-SS). Independent predictors of mortality were MV, septic shock and weight. A favorable evolution occurred in 81.4% of WARD patients; in 70.9% of ICU; in 39.6% of ICU-MV and in 27.6% of ICU-MV-SS patients. Severity of illness on admission, age, weight and heart rate were independently associated with evolution. No major adverse effects were recorded. The lack of a control group precluded the estimation of efficacy. However, our 26% mortality rate was higher than that of the treatment arm of clinical trials comparing plasma with usual treatment, which might be ascribed to higher proportion of patients with MV and septic shock in our cohort.

Resumen Se trata de un estudio multicéntrico de cohorte retrospectivo, observacional, desde 15/5 a 1/7, 2020, en 272 pacientes COVID-19 internados en hospitales de la provincia de Buenos Aires, incluidos en un programa de acceso expandido de plasma de convalecientes de COVID-19. Nuestros objetivos fueron analizar letalidad y sus factores de riesgo independientes, y evaluar la evolución favorable, definida como alta hospitalaria, permanencia en sala (PISO), o alta de la UTI. Los pacientes fueron estratificados en 4 subgrupos: ingreso a PISO (n = 100) con neumonía y/o requerimiento de oxígeno; a UTI (n = 87); a UTI con requerimiento de ventilación mecánica (UTI-VM; n = 56), y a UTI-VM con shock séptico (UTI-VM-SS; n = 29). La letalidad total a los 28 días fue 26.1%, (71/272), para PISO 14.0%; UTI, 18.4%; UTI-VM, 44.6%; y UTI-VM-SS, 55.2%. El tiempo medio de supervivencia (días): 25.6 ± 0.6 (PISO); 25.3 ± 0.7 (UTI); 20.8 ± 1.2 (UTI-VM) y 18.2 ± 1.8 (UTIVMSS). Los predictores independientes de letalidad fueron VM, shock séptico y peso. Se registró una evolución favorable en 81.4% de los pacientes en PISO; 70.9% en UTI, 39.6% en UTI-VM, y en 27.6% de UTI-VM-SS. La gravedad al ingreso, edad, peso y frecuencia cardíaca fueron predictores independientes de evolución. No se registraron efectos adversos graves. Por falta de un grupo control, no fue posible evaluar la eficacia del plasma de convaleciente. La letalidad (26%) fue mayor que en otros ensayos clínicos con plasma convaleciente; esto podría deberse a mayor proporción de aquellos con VM y shock séptico en nuestra cohorte.

ABSTRACT In the present work, we provide the first approach about the life-history of Brachionus plicatilis in South America. We tested with laboratory experiments the response of the pampean strain of B. plicatilis for two of its main stressors (conductivity and temperature). We evaluated the effects of eight conductivity values from 1 to 17 mS.cm-1 and two temperatures (15 and 25 °C) to compare its abundance with those obtained in the pampean lotic and lentic environments, where this rotifer is frequent or dominant. The results demonstrated that the increase in population-growth rate and the peak of abundance occurred at the highest temperature and at medium conductivity. Minimum values were obtained at the lowest temperature and conductivities analyzed, but the final density attained was nevertheless similar to those recorded in the pampean environments at the optimum conductivity and during the spring and summer seasons. Males, mictic females, and resting eggs were observed at the minimum and maximum conductivities, revealing the strategy of this species for maintaining dominance in environments with fluctuating salinity. The experiments also indicated the possible behavior of this relevant member of the zooplankton community within a scenario of increasing temperature and salinity related to the climate changes occurring in the pampean region.