Clinical outcomes of severe COVID-19 patients receiving early VV-ECMO and the impact of pre-ECMO ventilator use.

Acute respiratory distress syndrome (ARDS) in COVID-19 patients is associated with poor clinical outcomes and high mortality rates, despite the use of mechanical ventilation. Veno-Venous Extracorporeal membrane Oxygenation (VV-ECMO) in these patients is a viable salvage therapy. We describe clinical outcomes and survival rates in 52 COVID-19 patients with ARDS treated with early VV-ECMO at a large, high-volume center ECMO program. Outcomes included arterial blood gases, respiratory parameters, inflammatory markers, adverse events, and survival rates. Patients' mean age was 47.8 ± 12.1 years, 33% were female, and 75% were Hispanic. At the end of study period, 56% (n = 29) of the patients survived and were discharged and 44% (n = 23) of the patients expired. Survival rate was 75.0% (9 out of 12) in patients placed on ECMO prior to mechanical ventilation. Longer duration on mechanical ventilation prior to ECMO intervention was associated with a 31% (aOR = 1.31, 95% CI, 1.00-1.70) increased odds of mortality after adjusting for age, gender, BMI, number of comorbid conditions, and post-ECMO ventilator days. Early and effective ECMO intervention in critical ill COVID-19 patients might be a valuable strategy in critical care settings to increase their odds of survival.

Conditional control of gene function by an invertible gene trap in zebrafish.

Conditional mutations are essential for determining the stage- and tissue-specific functions of genes. Here we achieve conditional mutagenesis in zebrafish using FT1, a gene-trap cassette that can be stably inverted by both Cre and Flp recombinases. We demonstrate that intronic insertions in the gene-trapping orientation severely disrupt the expression of the host gene, whereas intronic insertions in the neutral orientation do not significantly affect host gene expression. Cre- and Flp-mediated recombination switches the orientation of the gene-trap cassette, permitting conditional rescue in one orientation and conditional knockout in the other. To illustrate the utility of this system we analyzed the functional consequence of intronic FT1 insertion in supv3l1, a gene encoding a mitochondrial RNA helicase. Global supv311 mutants have impaired mitochondrial function, embryonic lethality, and agenesis of the liver. Conditional rescue of supv311 expression in hepatocytes specifically corrected the liver defects. To test whether the liver function of supv311 is required for viability we used Flp-mediated recombination in the germline to generate a neutral allele at the locus. Subsequently, tissue-specific expression of Cre conditionally inactivated the targeted locus. Hepatocyte-specific inactivation of supv311 caused liver degeneration, growth retardation, and juvenile lethality, a phenotype that was less severe than the global disruption of supv311. Thus, supv311 is required in multiple tissues for organismal viability. Our mutagenesis approach is very efficient and could be used to generate conditional alleles throughout the zebrafish genome. Furthermore, because FT1 is based on the promiscuous Tol2 transposon, it should be applicable to many organisms.