Ventilation inhomogeneity and NO and CO diffusing capacity in ex-premature school children

• Published in: Respiratory medicine Vol. 140; pp. 94 - 100
• Main Authors: Sørensen, Jesper Kiehn, Buchvald, Frederik, Berg, Anna Korsgaard, Robinson, Paul D., Nielsen, Kim Gjerum
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-07-2018; Elsevier Limited
• Subjects: Adolescent; Age; Airway management; Birth weight; Birth Weight - physiology; Bronchodilator Agents - therapeutic use; Bronchodilators; Bronchopulmonary dysplasia; Bronchopulmonary Dysplasia - drug therapy; Bronchopulmonary Dysplasia - physiopathology; Carbon Monoxide; Case-Control Studies; Child; Children; Chronic respiratory disease; Correlation analysis; Dysplasia; Electrocardiography; Female; Follow-Up Studies; Gestational Age; Humans; Impairment; Infant, Newborn; Infant, Premature - physiology; Inhomogeneity; Long-term outcome; Longitudinal studies; Lung function; Lungs; Male; Mechanical ventilation; Nitric Oxide; Plethysmography; Premature birth; Premature Birth - physiopathology; Prematurity; Pulmonary Diffusing Capacity - drug effects; Pulmonary Diffusing Capacity - physiology; Questionnaires; Respiratory tract; Software; Spirometry - methods; Ventilation; Ventilators; Bronchopulmonary dysplasia; Lung function; Prematurity; Long-term outcome; Chronic respiratory disease
• ISSN: 0954-6111; 1532-3064
• DOI: 10.1016/j.rmed.2018.06.006

Ex-premature school children show mild-to-moderate airway obstruction and decreased CO diffusing capacity. Multiple breath nitrogen washout (N2MBW) and NO diffusing capacity (DLNO) measurements may provide new insight into long-term pulmonary and vascular impairment in bronchopulmonary dysplasia (BPD).
We examined a randomly selected group of 70 ex-premature children (gestational age <28 weeks or birth weight <1500 g; 42 with and 28 without BPD) and 38 term-born healthy controls of 8–13 years of age. Subjects performed N2MBW (lung clearance index, LCI; Sacin, and Scond), DLNO (membrane related diffusing capacity, Dm and pulmonary capillary volume, Vc), Fractional exhaled NO, CO diffusing capacity, conventional spirometry (FEV1, FVC, FEF25-75) and plethysmography (RV, TLC). Respiratory symptoms were assessed by questionnaire.
Compared to healthy controls, the BPD group had higher z-scores for lung clearance index (P = 0.003), Sacin (P = 0.005), lower CO diffusing capacity (P = 0.025), DLNO (P = 0.022), DLNO/VA z-scores (P = 0.025) and a significant larger proportion had respiratory complaints. Amongst ex-premature children, the BPD group did not differ from the non-BPD group except for a decreased Dm (P = 0.023). Ex-premature with BPD showed predominantly airway obstruction (FEV1/FVC; P < 0.0001), signs of hyperinflation (RV/TLC-ratio; P = 0.028), and 25% had a positive bronchodilator response (>12% in FEV1).
Ex-premature school children exhibited relatively mild but significant long-term respiratory symptoms and pulmonary peripheral impairment judged by N2MBW and DLNO measurements along with well-known airway obstruction. Larger longitudinal studies are needed to assess the clinical use of these advanced methods of assessing ventilation inhomogeneity and DLNO.
•Significant impairment of peripheral airways and alveolar membrane in ex-prematures.•Higher MBW indices including LCI and Sacin in ex-prematures compared to healthy.•Lower DLNO and DLNO/DLCO ratio suggesting alveolar membrane impairment.•Subjective respiratory complaints in ex-premature children 8–13 years later.•Significant bronchodilator responsiveness in 25% of ex-prematures.