BACKGROUND: The lower airway concentration of fractional exhaled nitric oxide (FENO) is unknown in children with chronic lung disease of infancy who have tracheostomy for long-term mechanical ventilation. We aimed to evaluate an online method of measuring FENO in a cohort of ventilator-dependent children with a tracheostomy and to explore the relationship between the peak FENO concentration (FENO peak) and the degree of respiratory support using the respiratory severity score.
METHODS: We conducted a prospective cross-sectional study in 31 subjects who were receiving long-term respiratory support through a tracheostomy. We measured the FENO peak and FENO plateau concentration from the tip of the tracheostomy tube using a nitric oxide analyzer in subjects during a quiet state while being mechanically ventilated. We obtained 2 consecutive 2-min duration measurements from each subject. The FENO peak, exhaled NO output (equal to the FENO peak × minute ventilation), and pulmonary NO excretion (exhaled NO output/weight) were calculated and correlated with the respiratory severity score.
RESULTS: The median FENO peak was 2.69 ppb, and the median FENO plateau was 1.57 ppb. The coefficients of repeatability between the 2 consecutive measurements for FENO peak and FENO plateau were 0.74 and 0.59, respectively. The intraclass coefficient between subjects within the cohort was 0.988 (95% CI 0.975-0.994, P < .001) for FENO peak and 0.991 (95% CI 0.982-0.996, P < .001) for FENO plateau. We found that the FENO peak was directly correlated with minute ventilation, but we did not find a direct relationship between the FENO peak concentration, exhaled NO output, or pulmonary NO excretion and respiratory severity score.
CONCLUSIONS: FENO peak and plateau concentration can be measured online easily with a high degree of reliability and repeatability in infants and young children with a tracheostomy. FENO peak concentration from the lower airway is low and influenced by minute ventilation in children receiving mechanical ventilation.
Breath Tests; Cross-Sectional Studies; Exhalation; Female; Humans; Infant; Infant, Newborn; Lung; Lung Diseases; Male; Nitric Oxide; Prospective Studies; Reproducibility of Results; Respiratory Function Tests; Tracheostomy
chronic lung disease of infancy; fractional exhaled nitric oxide; tracheostomy
Murthy VR, Escobar H, Norberg M, et al. A Novel Method of Measuring Fractional Exhaled Nitric Oxide in Tracheostomized Ventilator-Dependent Children. Respir Care. 2017;62(5):595-601. doi:10.4187/respcare.04858