Objective To explore the clinical diagnostic value of fractional exhaled nitric oxide (FeNO) in patients with ventilator-associated pneumonia (VAP).

Methods The patients needing invasive mechanical ventilation were selected in the Intensive Care Unit (ICU) in Fuxing Hospital, Capital Medical University. The demographic characteristics, FeNO, white blood cell (WBC), procalcitonin (PCT) values on day 1, 3, 5, 7 after ICU admission, and prognostic factors were analyzed. The early diagnostic value of FeNO for VAP was prospectively observed. Patients were divided into pneumonia group, extrapulmonary inflammation group, and non-inflammation group according to the reasons for ICU admission. And patients with mechanical ventilation lasted more than 3 days were divided into VAP group and non-VAP group according to episode of VAP within 14 days after ICU admission.

Results FeNO value in pneumonia group was significantly higher than that in extrapulmonary inflammation group and non-inflammation group (P < 0.05). Compared to the patients in non-VAP group, the FeNO value in VAP group significantly increased, and the FeNO on day 3 and day 5 had a good clinical predictive value for the VAP (day 3:AUC was 0.87, P < 0.001, cut-off value was 6.5 ppb, with 76.9% of sensitivity, 81.4% of specificity; day 5:AUC was 0.75, P=0.001, cut-off was 5.5 ppb, with 73.1% of sensitivity, 67.4% of specificity). The patients in the VAP group had shorter length of non-mechanical ventilation (P < 0.05) and longer length of ICU stays (P < 0.05) with 28 days.

Conclusions FeNO value increased significantly in patients with pneumonia, and increased FeNO had a good clinical predictive value for VAP, and can be used as a biomarker for VAP in clinical practice.