High-dose inhaled nitric oxide for severe pneumonia caused by multidrug-resistant bacteria: a randomized controlled...

Severe pneumonia caused by multidrug-resistant (MDR) bacteria is associated with high mortality. Inhaled nitric oxide (NO) has antimicrobial activity, but clinical evidence in MDR severe pneumonia remains limited. This trial will evaluate the efficacy and safety of adjunctive high-dose inhaled NO in patients with severe pneumonia associated with MDR bacteria.

This prospective, single-center, double-blind randomized controlled trial will be conducted at Jiangdu People's Hospital Affiliated with Yangzhou University from January 2026 to June 2027. Patients with suspected or confirmed severe pneumonia caused by MDR bacteria will be randomized 1:1 to standard treatment plus inhaled NO (200 ppm, twice daily for 30 min/session for 5 days) or standard treatment plus sham inhalation (0 ppm NO). The primary outcome is the change in Clinical Pulmonary Infection Score (CPIS) from baseline to day 7. Secondary outcomes include mortality, 28-day ventilator-free days, vasopressor-free days, antibiotic-free days, ICU-free days, and hospital-free days, CPIS and Sequential Organ Failure Assessment scores, microbiological eradication, citrullinated histone H3 and cell-free DNA concentrations, and ratio of arterial partial pressure of oxygen to fraction of inspired oxygen (PaO₂/FiO₂) ratios. Safety outcomes include methemoglobin and NO₂ thresholds, serum creatinine, airway hyperreactivity, and acute kidney injury. Primary and secondary outcomes will be analyzed in confirmed MDR participants; safety will be assessed in participants receiving at least one study-gas administration.

This protocol tests a mechanistically plausible adjunctive therapy for MDR severe pneumonia. It will explore whether high-dose NO affects neutrophil extracellular trap activity.