Background Zinc is a trace element that plays a role in stimulating innate and acquired immunity. The role of zinc in critically ill patients with COVID-19 remains unclear. This study aims to evaluate the efficacy and safety of zinc sulfate as adjunctive therapy in critically ill patients with COVID-19. Methods Patients aged ≥ 18 years with COVID-19 who were admitted to the intensive care unit (ICU) in two tertiary hospitals in Saudi Arabia were retrospectively assessed for zinc use from March 1, 2020 until March 31, 2021. After propensity score matching (1:1 ratio) based on the selected criteria, we assessed the association of zinc used as adjunctive therapy with the 30-day mortality. Secondary outcomes included the in-hospital mortality, ventilator free days, ICU length of stay (LOS), hospital LOS, and complication (s) during ICU stay. Results A total of 164 patients were included, 82 patients received zinc. Patients who received zinc sulfate as adjunctive therapy have a lower 30-day mortality (HR 0.52, CI 0.29, 0.92; p = 0.03). On the other hand, the in-hospital mortality was not statistically significant between the two groups (HR 0.64, CI 0.37–1.10; p = 0.11). Zinc sulfate use was associated with a lower odds of acute kidney injury development during ICU stay (OR 0.46 CI 0.19–1.06; p = 0.07); however, it did not reach statistical significance. Conclusion The use of zinc sulfate as an additional treatment in critically ill COVID-19 patients may improve survival. Furthermore, zinc supplementation may have a protective effect on the kidneys.

Background Inhaled nitric oxide (iNO) is used as rescue therapy in patients with refractory hypoxemia due to severe COVID-19 acute respiratory distress syndrome (ARDS) despite the recommendation against the use of this treatment. To date, the effect of iNO on the clinical outcomes of critically ill COVID-19 patients with moderate-to-severe ARDS remains arguable. Therefore, this study aimed to evaluate the use of iNO in critically ill COVID-19 patients with moderate-to-severe ARDS. Methods This multicenter, retrospective cohort study included critically ill adult patients with confirmed COVID-19 treated from March 01, 2020, until July 31, 2021. Eligible patients with moderate-to-severe ARDS were subsequently categorized into two groups based on inhaled nitric oxide (iNO) use throughout their ICU stay. The primary endpoint was the improvement in oxygenation parameters 24 h after iNO use. Other outcomes were considered secondary. Propensity score matching (1:2) was used based on the predefined criteria. Results A total of 1598 patients were screened, and 815 were included based on the eligibility criteria. Among them, 210 patients were matched based on predefined criteria. Oxygenation parameters (PaO2, FiO2 requirement, P/F ratio, oxygenation index) were significantly improved 24 h after iNO administration within a median of six days of ICU admission. However, the risk of 30-day and in-hospital mortality were found to be similar between the two groups (HR: 1.18; 95% CI: 0.77, 1.82; p = 0.45 and HR: 1.40; 95% CI: 0.94, 2.11; p= 0.10, respectively). On the other hand, ventilator-free days (VFDs) were significantly fewer, and  ICU and hospital LOS were significantly longer in the iNO group. In addition, patients who received iNO had higher odds of acute kidney injury (AKI) (OR (95% CI): 2.35 (1.30, 4.26), p value = 0.005) and hospital/ventilator-acquired pneumonia (OR (95% CI): 3.2 (1.76, 5.83), p value = 0.001). Conclusion In critically ill COVID-19 patients with moderate-to-severe ARDS, iNO rescue therapy is associated with improved oxygenation parameters but no mortality benefits. Moreover, iNO use is associated with higher odds of AKI, pneumonia, longer LOS, and fewer VFDs.