Lung function measurement in prematurely born preschool children with and without chronic lung disease

Abstract

Objective: Prematurely born infants often have recurrent wheeze and long-term respiratory morbidity at follow-up. Assessment of airways obstruction in preschool children is feasible using the interrupter resistance (Rint) but has rarely been examined in preterm children with and without chronic lung disease (CLD). The objective of this study was to determine lung function measured by the interrupter technique, its feasibility in the ambulatory setting and respiratory health in prematurely born preschool children with and without CLD.Study Design: Preterm children of 2 to 4 years with severe CLD (>30% oxygen at 36 weeks and discharged home receiving supplemental oxygen) (n ¼ 43, median gestational age 27 weeks and median birth weight 995 g) and without CLD (n ¼ 33, median gestational age 29 weeks and median birth weight 1366 g) attempting lung function test for the first time were enrolled. Respiratory symptoms score was calculated using a questionnaire. A single set of 10 consecutive Rint measurements was obtained using a portable device (MicroRint). Median of at least five occlusions with consistent shape of mouth pressure-time curves was taken to be a Rint measurement. To assess feasibility the children were categorized as 'satisfactory', 'failure' and 'rejected' depending on the outcome of the test. Outcome variables were respiratory symptoms score and Rint.Result: Satisfactory Rint measurement was obtained in 46 (61%) children, 9 (36%) 2-year olds, 17 (65%) 3-year olds and 20 (80%) 4-year olds. As compared with the preterm control children (n ¼ 18), CLD children (n ¼ 28) had significantly higher respiratory symptoms score (18.5 vs 6, P<0.01) and Rint expressed as absolute values (kPa l À1 ) and z-scores (1.33 vs 1.16 and 1.42 vs 1.0, P<0.01), respectively. Conclusion:Rint measurement is feasible in prematurely born children of preschool age in the ambulatory setup. Preschool children with severe CLD may be identified from preterm children without CLD by increased Rint that may be used as a screening tool and as an outcome measure for interventions.

“New” Bronchopulmonary Dysplasia

“…This airway obstruction was more prominent in former premature infants with new BPD, compared with those without BPD. 54 Oscillometry has been utilized to identify obstructive lung disease early, as this technique uses tidal breathing, which is easier to obtain in a young child compared with the forced expiratory maneuver. 44,55 Data from studies that have used this technique reveal that reactance at low frequencies was a sensitive marker for lung dysfunction, and that X5 and FEV1 correlated well in this group of patients.…”

Lung function in a cohort of 5‐year‐old children born very preterm

“…Previous studies assessing pulmonary function in very preterm children at preschool age were mainly focused on those with bronchopulmonary dysplasia (BPD), and the general population of these children has been considered only recently . Studies investigating lung function and its perinatal determinants in area‐based prospective cohorts of very preterm children are scarce …”

Reference ranges for interrupter resistance technique: the Asthma UK Initiative

“…Since equipment for its measurement is commercially available and requires only passive cooperation, Rint provides a suitable lung function test for young children. The technique is safe, quick, noninvasive, available, inexpensive, applicable in field studies, and delivers results that are clinically relevant [1][2][3][4][5][6][7][8][9][10][11][12], appear sufficiently valid [13] and which seem suitable for assessing bronchodilator responses [7,9,[14][15][16]. A European Respiratory Society (ERS)/American Thoracic Society (ATS) consensus statement was published in 2007, largely based on personal experience, in an attempt to make the procedure more uniform and facilitate comparisons between centres [17].…”