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Updated: Oct 2, 2025

A Novel Inhalation Mask System to Deliver High Concentrations of Nitric Oxide Gas in Spontaneously Breathing Subjects
Published on: May 4, 2021
High serum nitrates levels in non-survivor COVID-19 patients
L Lorente1, F Gómez-Bernal2, M M Martín3
1Intensive Care Unit, Hospital Universitario de Canarias, La Laguna, Santa Cruz de Tenerife, Spain.
Objective:
Higher blood nitrate and nitrite levels have been found in coronavirus disease 2019 (COVID-19) patients than in healthy subjects. The present study explores the potential association between serum nitrate levels and mortality in COVID-19 patients.
Design:
A prospective observation study was carried out.
Setting:
Eight Intensive Care Units (ICUs) from 6 hospitals in the Canary Islands (Spain).
Patients:
COVID-19 patients admitted to the ICU.
Interventions:
Determination of serum nitrate levels at ICU admission.
Main Variable Of Interest:
Mortality at 30 days.
Results:
Non-surviving (n=11) compared to surviving patients (n=42) showed higher APACHE-II (p<0.001) and SOFA scores (p=0.004), and higher serum nitrate levels (p=0.001). Logistic regression analyses showed serum nitrate levels to be associated to 30-day mortality after controlling for SOFA (OR=1.021; 95%CI=1.006-1.036; p=0.01) or APACHE-II (OR=1.023; 95%CI=1.006-1.041; p=0.01). There were no differences in the area under the curve (AUC) for mortality prediction by serum nitrate levels (AUC=83%; 95%CI=73-92%; p<0.001), APACHE II (AUC=85%; 95%CI=75-96%; p<0.001) and SOFA (AUC=78%; 95%CI=63-92%; p=0.005) based on the DeLong method. The Kaplan-Meier analysis found patients with serum nitrates levels>68.4μmol/l to have a higher mortality rate (hazard ratio=138.8; 95%CI=22.3-863.9; p<0.001).
Conclusions:
The main novel finding was the association between serum nitrate levels and mortality in COVID-19 patients controlling for the SOFA or APACHE-II scores, though larger studies are needed to confirm this observation.
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