A Retrospective Analysis of Inhaled Nitric Oxide and Outcomes in Mechanically Ventilated Patients with COVID-19 ARDS

Background: Inhaled nitric oxide (iNO) is a selective pulmonary vasodilator used as rescue therapy in acute respiratory distress syndrome (ARDS) for transient improvement in oxygenation. Although multiple studies demonstrate improvements in oxygenation parameters, iNO has not consistently shown a mortality benefit or reduced ventilation duration. Methods: A retrospective cohort study was conducted of mechanically ventilated adults with SARS-CoV-2 (COVID-19) admitted to a medical intensive care unit who received iNO. Demographic characteristics, comorbidities, illness severity scores, timing of iNO initiation, and clinical outcomes were analyzed, with comparisons made between survivors and non-survivors. Results: A total of 94 patients were included. The mean age was 52.0 years (Standard Deviation (SD) 14.1), 70.2% were male, and the mean body mass index was 36.5 kg/m² (SD 10.0). Hypertension (58.5%) and diabetes (36.2%) were the most common comorbidities. The mean Sequential Organ Failure Assessment (SOFA) score was 4.22 (SD 2.79), and the mean Acute Physiology and Chronic Health Evaluation II (APACHE II) score was 11.69 (SD 6.98). Overall, in-hospital mortality was 85.1% (80/94). The median time from intubation to iNO initiation was 7.6 days (mean 7.7 days). Survivors received iNO significantly earlier than non-survivors (mean 4.14 vs. 8.3 days after intubation, p = 0.024) and had a longer hospital length of stay (mean 37 vs. 23 days, p < 0.01). Duration of iNO therapy did not differ between groups (p = 0.12). Conclusions: In this cohort of critically ill patients with COVID-19 and severe respiratory failure, overall mortality was extremely high. Earlier initiation of inhaled nitric oxide was associated with improved survival, whereas duration of therapy was not. These findings suggest that the timing of iNO administration may be associated with clinical outcomes and warrant further prospective investigation to confirm this association.