COVID-19 versus Non-COVID-19 Acute Respiratory Distress Syndrome: Comparison of Demographics, Physiologic Parameters, Inflammatory Biomarkers, and Clinical Outcomes

Rationale: There is an urgent need for improved understanding of the mechanisms and clinical characteristics of acute respiratory distress syndrome (ARDS) due to coronavirus disease (COVID-19).Objectives: To compare key demographic and physiologic parameters, biomarkers, and clinical outcomes of COVID-19 ARDS and ARDS secondary to direct lung injury from other etiologies of pneumonia.Methods: We enrolled 27 patients with COVID-19 ARDS in a prospective, observational cohort study and compared them with a historical, pre-COVID-19 cohort of patients with viral ARDS (n = 14), bacterial ARDS (n = 21), and ARDS due to culture-negative pneumonia (n = 30). We recorded clinical demographics; measured respiratory mechanical parameters; collected serial peripheral blood specimens for measurement of plasma interleukin (IL)-6, IL-8, and IL-10; and followed patients prospectively for patient-centered outcomes. We conducted between-group comparisons with nonparametric tests and analyzed time-to-event outcomes with Kaplan-Meier and Cox proportional hazards models.Results: Patients with COVID-19 ARDS had higher body mass index and were more likely to be Black, or residents of skilled nursing facilities, compared with those with non-COVID-19 ARDS (P < 0.05). Patients with COVID-19 had lower delivered minute ventilation compared with bacterial and culture-negative ARDS (post hoc P < 0.01) but not compared with viral ARDS. We found no differences in static compliance, hypoxemic indices, or carbon dioxide clearance between groups. Patients with COVID-19 had lower IL-6 levels compared with bacterial and culture-negative ARDS at early time points after intubation but no differences in IL-6 levels compared with viral ARDS. Patients with COVID-19 had longer duration of mechanical ventilation but similar 60-day mortality in both unadjusted and adjusted analyses.Conclusions: COVID-19 ARDS bears several similarities to viral ARDS but demonstrates lower minute ventilation and lower systemic levels of IL-6 compared with bacterial and culture-negative ARDS. COVID-19 ARDS was associated with longer dependence on mechanical ventilation compared with non-COVID-19 ARDS. Such detectable differences of COVID-19 do not merit deviation from evidence-based management of ARDS but suggest priorities for clinical research to better characterize and treat this new clinical entity.

Abnormal CD40 ligand (CD154) expression in human immunodeficiency virus-infected children

The CD40 ligand (CD154), expressed primarily on activated CD4-positive T cells, is a costimulatory molecule involved in B-cell proliferation, germinal center formation, and immunoglobulin class switching. Since B-cell abnormalities including hypergammaglobulinemia and abnormal antibody-specific immune responses are prominent and occur early during the course of pediatric human immunodeficiency virus (HIV) infection, we measured the baseline levels and the induced levels of expression of CD154 on CD3(+) CD8(-) (T helper cells) in HIV-infected children and uninfected children born to HIV-positive mothers. The percentage of CD154(+) T helper cells activated in vitro and the level of CD154 expressed per T helper cell (mean fluorescent channel [MFC]) were significantly lower in the HIV-infected children than in the uninfected control group (77% +/- 3% versus 89% +/- 1%, respectively [P < 0.002], and 261 +/- 174 versus 415 +/- 130 MFC, respectively [P < 0.03]). The levels of CD154 expressed on resting T helper cells in the HIV-infected group were not significantly different from the levels observed in the control group. In the HIV-infected children, the level of CD154 on activated T helper cells correlated with the level of immunodeficiency, as assessed by the CD4 T-cell levels (correlation coefficient [r] = 0.707, P = 0.003), but did not correlate with the viral load or with any of the serum immunoglobulin concentrations measured in this group of HIV-infected children. The baseline level of CD154 expressed on T helper cells did, however, correlate with the concentration of immunoglobulin A in serum. We conclude that HIV-infected children have impaired regulation of CD154 expression which may contribute to the immune dysregulation commonly observed.