Sanja Zivanovic

Longitudinal assessment of lung function in extremely prematurely born children

To assess longitudinally small airway function in children born extremely prematurely and whether there was a correlation between airway function in infancy and at 11‐14 years.

P09 Pulmonary artery pressures in school age children born very prematurely

Aim Bronchopulmonary dysplasia, which occurs most frequently in extremely prematurely born infants, can be complicated by pulmonary hypertension due to dysregulation of angiogenesis and increased muscularisation of the pulmonary arteries. (1) Our aim study was to assess, whether at school age, pulmonary artery pressures differed between children born very prematurely and those born at term. Methods Transthoracic echocardiography was performed at 11–14 years in children born extremely prematurely (<29 weeks of gestation) who had been entered into the United Kingdom Oscillation Study and in term born children. Measurements were performed according to the American Society of Echocardiography guidelines. Tricuspid regurgitation (TR) was assessed in the apical four-chamber view and parasternal right ventricular inflow. A minimum of three sequential complexes were recorded. Continuous-wave Doppler of the peak regurgitant jet velocity was used to estimate the right-ventricular-to-right-atrial (RV-RA) systolic pressure gradient with the use of the modified Bernoulli equation. The mean RV-RA gradient was calculated by tracing the TR time-velocity integral. (2) Pulmonary hypertension was defined as a peak TR jet velocity ≥ 2.5 m per second. The difference in the echocardiographic results between term and preterm children were examined using mixed models, which allowed for clustering due to multiple births. The p-values reported are based on unadjusted models. Results Echocardiographic results were analysed from 191 preterm and 45 term born children. The preterm compared to the term born children had higher mean TR peak velocity (2.21 vs. 1.89, p < 0.001), systolic RV-RA gradient (19.9 vs. 14.5, p < 0.001) and mean RV-RA gradient (14.0 vs. 11.3, p < 0.001). TR velocity was measurable in 78% of term born and 69% of preterm children; 13% of preterm children, but no term born child had a peak TR velocity of >2.5 m/s (p = 0.011). Conclusion Extremely prematurely born children have higher pulmonary artery pressures at school age than those born at term. References Mourani PM et al, Pulmonary vascular effects of inhaled nitric oxide and oxygen tension in bronchopulmonary dysplasia. Am J Respir Care Med 2004;170:1006–1013 Fikret E. et al, Accuracy of Doppler-Echocardiographic Mean Pulmonary Artery Pressure for Diagnosis of Pulmonary Hypertension, www.plosone.org, Dec2010, Volume 5, Issue 12

Effect of dexamethasone exposure on the neonatal unit on the school age lung function of children born very prematurely

The objective of this study was to determine the impact of postnatal dexamethasone treatment on the neonatal unit on the school age lung function of very prematurely born children. Children born prior to 29 weeks of gestational age had been entered into a randomised trial of two methods of neonatal ventilation (United Kingdom Oscillation Study). They had comprehensive lung function measurements at 11 to 14 years of age. One hundred and seventy-nine children born at a mean gestational age of 26.9 (range 23–28) weeks were assessed at 11 to 14 years; 50 had received postnatal dexamethasone. Forced expiratory flow at 75% (FEF75), 50%, 25% and 25–75% of the expired vital capacity, forced expiratory volume in one second, peak expiratory flow and forced vital capacity and lung volumes including total lung capacity and residual volume were assessed. Lung function outcomes were compared between children who had and had not been exposed to dexamethasone after adjustment for neonatal factors using linear mixed effects regression. After adjustment for confounders all the mean spirometry results were between 0.38 and 0.87 standard deviations lower in those exposed to dexamethasone compared to the unexposed. For example, the mean FEF75 z-score was 0.53 lower (95% CI 0.21 to 0.85). The mean lung function was lower as the number of courses of dexamethasone increased. In conclusion, postnatal dexamethasone exposure was associated with lower mean lung function at school age in children born extremely prematurely. Our results suggest the larger the cumulative dose the greater the adverse effect on lung function at follow-up.

Pulmonary Artery Pressures in School-Age Children Born Prematurely

Objectives To test the hypothesis that pulmonary artery pressures were higher in school aged children born extremely premature than those born at term. We also wanted to assess whether pulmonary artery pressures differed between children born prematurely with or without bronchopulmonary dysplasia (BPD) or between those randomized in the neonatal period to different ventilation modes. Study design Transthoracic echocardiography was performed on 193 children born extremely premature (106 had BPD) and 110 children born at term when they were 11–14 years of age. Ninety‐nine children born extremely premature had been supported by high‐frequency oscillation and 94 by conventional ventilation. Tricuspid regurgitation was assessed in the apical 4‐chamber and modified parasternal long‐axis views. Continuous‐wave Doppler of the peak regurgitant jet velocity was used to estimate the right‐ventricular‐to‐right‐atrial systolic pressure gradient. Results Tricuspid regurgitation was measurable in 71% (137/193) of the children born preterm and 75% (83/110) of the children born at term (P .23). The children born prematurely compared with the children born at term had a greater peak tricuspid regurgitation velocity (2.21 vs 1.95 m/s, P < .001) and the children born prematurely who had BPD vs those without BPD had a greater peak tricuspid regurgitation velocity (P = .023). There were no significant differences in pulmonary artery pressures according to neonatal ventilation mode. Conclusions Pulmonary artery pressures were estimated to be greater in 11‐ to 14‐year‐old children born extremely prematurely compared with those born at term and in those born prematurely who developed BPD compared with those who did not but did not differ significantly by neonatal ventilation mode.

G155 Small For Gestational Age at Birth and Lung Function at School Age in Very Prematurely Born Children

Background Very prematurely born infants who were small for gestation age (SGA) at birth, despite routine use of antenatal corticosteroids and postnatal surfactant, had increased respiratory morbidity in infancy – increased rates of BPD and hospital readmissions for respiratory disorders (1). Aim To test the hypothesis that amongst children born very prematurely, those who were SGA would have greater lung function abnormalities at school age. Methods Lung function was assessed at 12 to 13 years of age in 204 children born <29 weeks of gestational age; 50 were SGA (<10th centile for weight). They had been entered into the United Kingdom Oscillation Study and randomised within one hour after birth to receive high frequency oscillation or conventional ventilation. There were no significant differences in short term outcomes (2), hence the results of the children in the two arms were pooled for this study. Forced expiratory volume in one second (FEV1), forced vital capacity (FVC), FEV1:FVC, residual volume (RV), diffusion factor for carbon monoxide (DLCO), functional residual capacity (FRCpleth) and maximum expiratory flow at 24, 50, 75% of vital capacity (MEF25,50,75) were assessed. The results were expressed as z-scores. The response to a cold air challenge (CACh) was considered positive if FEV1 fell by >10% of baseline. Results At the time of assessment, compared to the non SGA children, the SGA children had lower weight (p < 0.001) and height (p = 0.002). The SGA children had lower mean z-scores for FEV1 (p < 0.001), FEV1/FVC (P = 0.009), DLCO (p = 0.013), MEF25 (p = 0.005), MEF50 (p = 0.002) and MEF75 (p < 0.001) and a higher mean FRCpleth z-score (p = 0.010). There was no significant difference regarding the proportion of SGA and non SGA children responding to a CACh (p = 0.091). Conclusion These results suggest that amongst very prematurely born children, being SGA at birth is associated with greater restrictive and obstructive (particularly of small airways) lung function abnormalities at school age. References Peacock J, Marston L, Marlow N, et al Neonatal and infant outcome in boys and girls born very prematurely. Ped Res 2012; 71:305–310. Johnson AH, Peacock JL, Greenough A, et al High frequency oscillatory ventilation for the prevention of chronic lung disease of prematurity. New Engl J Med 2002; 347:633–642.