Background: Conservative fluid management improves outcomes in mechanically ventilated adults with ARDS, but its impact across the broader spectrum of acute respiratory failure is less clear. The SARS-CoV-2 pandemic provided an opportunity to assess this relationship in patients with a relatively uniform lung injury mechanism. We examined associations between daily fluid balance and respiratory status in adults hospitalized with SARS-CoV-2 across varying degrees of respiratory impairment. Methods: Retrospective cohort study of adults hospitalized with SARS-CoV-2 within ±7 days of admission to five hospitals in an academic medical system (March 2020–July 2022). The primary outcome was a modified WHO Clinical Scale (mWHO) from 1 (Hospitalized, no respiratory support) to 5 (Death or discharge to hospice). Associations between daily net fluid balance and next-day mWHO were tested using cumulative logistic regression and adjacent-categories logistic regression, adjusting for demographics, comorbidities, hospital type, vasopressors, inotropes, renal replacement therapy, and unmeasured urine outputs. Results: Among 4,254 patients (median age 58 41–70; 52.9% male; median hospital stay 4.5 2.5–8.1 days), 2,860 (67.2%) required respiratory support, 539 (12.7%) received invasive ventilation, and 571 (13.4%) died. In critically ill adults, positive fluid balance was associated with higher odds of subsequent mechanical ventilation (OR per L 1.48, 95%CI 1.41–1.55) or death (OR 1.15, 95%CI 1.08–1.23). Among non-critically ill patients on low-flow oxygen, positive fluid balance was associated with improved respiratory status (OR 0.89, 95%CI 0.86–0.92). Conclusions: Positive fluid balance had divergent effects by illness severity, suggesting distinct physiologic or clinical mechanisms across the spectrum of SARS-CoV-2 respiratory failure.
Kerchberger et al. (Mon,) studied this question.