Introduction Spacer devices optimize delivery of aerosol therapies and maximize therapeutic efficacy. We assessed the impact of spacer device on the prevalence and magnitude of bronchodilator response (BDR) in children with asthma. Methods Children with physician confirmed asthma and parentally reported symptoms in the last 12 months were recruited for this study. Each participant completed two separate visits (5-10 days apart) with spirometry performed at baseline and following cumulative doses of salbutamol (200, 400, 800, and 200 mu g) delivered by either a small volume disposable spacer or a large volume multi-use spacer. Spacer type was alternated for each participant during each visit. The primary outcome was the effect of spacer type on bronchodilator responsiveness. The secondary outcome was to assess the relationships between spacer device, salbutamol dose and the proportion of children with a clinically relevant BDR. Results Thirty-two children (mean age 11.8 years) completed both visits. Change in lung function following bronchodilators was increased using the large volume spacer, for relative but not absolute increase in FEV1 [mean difference (95% confidence intervals): 1.28% (0.02, 2.54; P = 0.047) and 0.013 L (-0.01, 0.04; P = 0.288)], respectively. There was no observed difference in FVC by spacer type. Overall, 59% (n = 19) of children exhibited a clinically relevant BDR at 400 mu g of salbutamol for any spacer and was independent of spacer type. Conclusion Spacer device was not associated with clinically important differences in lung function following bronchodilator inhalation in children with asthma. At a recommended dose of 400 mu g, some children with asthma may have their bronchodilator responsiveness misclassified.

Rationale: Prenatal omega-3 fatty acids improve alveolarization, diminish inflammation, and improve pulmonary growth, but it is unclear whether these outcomes translate into improved postnatal lung function. Objective: We assessed the effect of prenatal supplementation with docosahexaenoic acid (DHA) on offspring lung function through 60 months of age. Methods: We included a cohort of 772 Mexican preschoolers whose mothers participated in a clinical trial (NCT00646360) of supplementation with DHA or a placebo from week 18-22 of gestation through delivery. Measurements: The children were followed after birth and anthropometric measurements and forced oscillation tests were performed at 36, 48, and 60 months of age. The effect of DHA was tested using a longitudinal mixed effect models. Results: Overall, mean (Standard Deviation) of the measurements of respiratory system resistance and respiratory system reactance at 6, 8, and 10 Hz during follow up period were 11.3 (2.4), 11.1 (2.4), 10.3 (2.2) and -5.2 (1.6), -4.8 (1.7), -4.6 (1.6), respectively. There were no significant differences in pulmonary function by treatment group. DHA did not affect the average lung function or the trajectories through 60 months. Conclusions: Prenatal DHA supplementation did not influence pulmonary function in this cohort of Mexican preschoolers.

ABSTRACT Background and objective Selecting ‘healthy’ preschool‐aged children for reference ranges may not be straightforward. Relaxing inclusion criteria for normative data does not affect spirometry z‐scores. We therefore investigated the effect of similarly relaxing inclusion criteria in preschoolers on reference ranges for respiratory impedance (Zrs) using a modified forced oscillation technique (FOT). Methods The International Study of Asthma and Allergies in Childhood questionnaire classified 585 children into a healthy and five mutually exclusive groups. Zrs was measured between 4 and 26 Hz and resistance (R) and compliance (C) obtained by model fitting. Prediction models were determined using mixed effect models and z‐scores compared between healthy children and the five groups. Results Zrs data were obtained for 494 participants (4.30 ± 0.7 years) on 587 occasions. Comparison of the Zrs z‐scores between the healthy children and the health groups found significant differences in children with asthma, current wheeze and respiratory symptoms, but not in children born preterm or with early‐life wheeze. Adding these two groups to the healthy dataset had no significant effect on the distribution of z‐scores and increased the size of the dataset by 22.3%. Conclusion Our data suggest that preschool‐aged children born preterm or with early‐life wheeze can be included in FOT reference equations, while those with asthma, current wheeze and respiratory symptoms within 4 weeks of testing should be excluded. This more inclusive approach results in more robust FOT reference ranges.

Hypoxia Challenge test (HCT) is the gold standard to predict the need for supplemental O2 during air travel. HCT has been validated in adults and older children but may not be suitable for infants born preterm. Aim: To investigate the agreement between HCT and inflight hypoxia in preterm infants Method: Preterm (<35 wk GA) aged 1-12m attended for HCT prior to air travel. Inflight, infants had SpO2 recorded and used supplemental O2 if SpO2 <85%. Post flight, oximeter data was analysed for SpO2 nadir. The agreement between HCT and inflight hypoxia was assessed with intra-class correlations and the influence of age on this agreement analysed using univariate logistic regression. Results: 30 preterm infants of GA(median(range)) 29.1w ( 23.6-34.6) with a corrected age of 22.5w (-1.7 - 50.9) were studied. 28 preterm infants with matching HCT completed 50 flights. HCT failed to predict inflight O2 need in 36% of flights in preterm infants. In 28% of flights, the infant passed the HCT, but failed inflight and required supplemental O2, and in 8% of flights the infant failed the HCT but did not require O2 inflight. Inflight response in 5 of 16 preterm infants with multiple flights was inconsistent with O2 being required on some but not all flights. Corrected age at time of test did not influence inflight response in the preterm infants (OR 0.986; CI= 0.942, 1.032; p = 0.537). Conclusion: In preterm infants, the HCT does not accurately predict inflight hypoxia. A false pass may put infants at risk of inflight desaturations when flying without supplemental O2 whereas a false fail leads to unneccesary use of supplemental O2. Further studies are needed to understand the physiological response to air travel in preterm infants.

The environmental factors which may affect children's respiratory health are complex, and the influence and significance of factors such as traffic, industry and presence of vegetation is still being determined. We undertook a cross-sectional study of 360 school children aged 5-12 years who lived on the outskirts of a heavy industrial area in Western Australia to investigate the effect of a range of environmental factors on respiratory health using the forced oscillation technique (FOT), a non-invasive method that allows for the assessment of the resistive and reactive properties of the respiratory system. Based on home address, proximity calculations were used to estimate children's exposure to air pollution from traffic and industry and to characterise surrounding green space. Indoor factors were determined using a housing questionnaire. Of the outdoor measures, the length of major roads within a 50m buffer was associated with increased airway resistance (Rrs8). There were no associations between distance to industry and FOT measures. For the indoor environment the presence of wood heating and gas heating in the first year of life was associated with better lung function. The significance of both indoor and outdoor sources of air pollution and effect modifiers such as green space and heating require further investigation.

Selecting “healthy” preschool aged children for reference ranges is not clear. Relaxing the strict exclusion criteria has been shown to have no significant effect on spirometry Z-scores when compared to healthy children (Lum, S et al. ERJ 2015;45: 1576-1581). We investigated the effect of health status in pre-schoolers on reference ranges for respiratory impedance (Zrs) using a modified forced oscillation technique (FOT). 585 children (4.3 ±. 68 years) were classified into health groups from the ISAAC questionnaire. Zrs was measured with FOT between 4-26 Hz and mean resistance (R) and compliance (C) were obtained by model fitting. Prediction models were determined by mixed effect modelling and Z-scores compared between healthy children and the health groups. Data were obtained in 88% of children. Compared to healthy children (n=295), R and C Z-scores were significantly increased in asthmatics (n=70) [0.25 ±1.03 (mean±SD) vs -0.01 ±0.99 hPa.s/L, p=0.05] and [-0.20(-1.08;0.43) vs 0.08(-0.51;0.74)hPa.s/L, p=0.03]. Presence of a respiratory tract infection within 4 weeks of testing (n=67) significantly increased R (-0.35±1.11 vs -0.01±0.99, p=0.01). R and C in those preterm (n=35), with early life wheeze (n=49) or who wheezed in the last 12 months (n=71) but not asthmatic were no different to healthy children [(p=0.50, p=0.24), (p=0.91, p=0.91), (p=0.21, p=0.12)]. Our data suggest that children with asthma or a current respiratory infection should not be included in reference equations but the usually strict inclusion criteria, excluding children born pre-term or with a history of wheeze can be relaxed for FOT. This more inclusive approach results in larger, more robust reference ranges.

Rationale Individual assessment of airway obstruction in preschool-age children requires sensitive and specific lung function methods with low demand of cooperation. Although the forced oscillation technique (FOT) is feasible in young children, conventional measurements of respiratory impedance (Zrs) have limited diagnostic power in individuals.Objective To find descriptors of within-breath Zrs that are sensitive indicators of airway obstruction during tidal breathing in children.Methods Zrs was measured with (i) a standard multifrequency FOT (4-26 Hz) to assess the mean values of resistance and reactance for whole breaths and (ii) a 10 Hz signal to track the within-breath changes. Various Zrs measures obtained in healthy children (n=75) and those with acute wheeze (n=31) were investigated with receiver operator characteristic (ROC) analysis. The cut-off values obtained for airway obstruction were then tested in children with recurrent wheeze (n=20) before and after administration of salbutamol.Results The largest area under the ROC curve (0.95) was observed for the tidal changes of resistance between the zero-flow values (Delta R). The Delta R cut-off value of 1.42 hPa s/L detected airway obstruction with sensitivity of 92% and specificity of 89% in children with acute wheeze and distinguished children with recurrent wheeze (16/20 above the cut-off value) from healthy children (22/23 below the cut-off value). Furthermore, Delta R significantly decreased after salbutamol in wheezy children but remained unchanged in healthy children.Conclusions New lung function measure Delta R is able to detect airway obstruction with high sensitivity and specificity and is suitable for use in lung function testing in young children.

RespirologyVolume 21, Issue S2 p. 7-11 Supplement Article ANZSRS Oral Presentations First published: 23 March 2016 https://doi.org/10.1111/resp.12752_2Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Volume21, IssueS2Supplement: Thoracic Society of Australia & New Zealand and the Australian & New Zealand Society of Respiratory Science, Annual Scientific MeetingApril 2016Pages 7-11 RelatedInformation

RespirologyVolume 21, Issue S2 p. 7-11 Supplement Article ANZSRS Oral Presentations First published: 23 March 2016 https://doi.org/10.1111/resp.12752_2Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Volume21, IssueS2Supplement: Thoracic Society of Australia & New Zealand and the Australian & New Zealand Society of Respiratory Science, Annual Scientific MeetingApril 2016Pages 7-11 RelatedInformation

The diagnostic value of FEV1 for assessing functional impairment in asthma has been debated, primarily because forced expiratory manoeuvres may alter bronchial tone. The forced oscillation technique (FOT) does not affect the baseline tone, thus may be a more appropriate tool to evaluate the bronchodilator response (BDR) in children. FOT and spirometry were performed before and after administration of 400 ug salbutamol in school-aged children with stable asthma. Mean R at 6 Hz (R6) was calculated for several breaths and the end-expiratory (ReE) and end-inspiratory (ReI) values at 10 Hz were also determined. Positive BDR was defined according to the guidelines. Four children had positive BDR with both the FOT and spirometry (Group 1, Table 1), 6 had positive BDR with FOT but not with FEV1 (Group 2) and 15 did not have a BDR with either technique (Group 3). Baseline ReE was elevated in Groups 1 and 2 as compared to Group 3 (p<0.05); however, ReI was significantly lower in Group 2 than in Group 1, suggesting that these children can dilate their airways during tidal breathing.The different patterns in the volume dependence suggest that the baseline airway tone in asthmatics can be reduced by the deep inspiration associated with the FEV1 test and hence remain hidden in children who exhibit positive BDR.