Maureen Verheggen

Respiratory impedance and bronchodilator responsiveness in healthy children aged 2-13 years

The forced oscillation technique (FOT) can be used in children as young as 2 years of age and in those unable to perform routine spirometry. There is limited information on changes in FOT outcomes in healthy children beyond the preschool years and the level of bronchodilator responsiveness (BDR) in healthy children. We aimed to create reference ranges for respiratory impedance outcomes collated from multiple centers. Outcomes included respiratory system resistance (Rrs) and reactance (Xrs), resonant frequency (Fres), frequency dependence of Rrs (Fdep), and the area under the reactance curve (AX). We also aimed to define the physiological effects of bronchodilators in a large population of healthy children using the FOT.

Home oxygen for children with acute bronchiolitis

A prospective randomised controlled pilot study was performed comparing home oxygen therapy with traditional inpatient hospitalisation for children with acute bronchiolitis. Children aged 3–24 months with acute bronchiolitis, still requiring oxygen supplementation 24 h after admission to hospital, were randomly assigned to receive oxygen supplementation at home with support from “hospital in the home” (HiTH) or to continue oxygen supplementation in hospital. 44 children (26 male, mean age 9.2 months) were recruited (HiTH n  =  22) between 1 August and 30 November 2007. Only one child from each group was readmitted to hospital and there were no serious complications. Children in the HiTH group spent almost 2 days less in a hospital bed than those managed as traditional inpatients: HiTH 55.2 h (interquartile range (IQR) 40.3–88.9) versus in hospital 96.9 h (IQR 71.2–147.2) p = 0.001. Home oxygen therapy appears to be a feasible alternative to traditional hospital oxygen therapy in selected children with acute bronchiolitis.

Pre-flight testing of preterm infants with neonatal lung disease: a retrospective review.

Background: The low oxygen environment during air travel may result in hypoxia in patients with respiratory disease. However, little information exists on the oxygen requirements of infants with respiratory disease planning to fly. A study was undertaken to identify the clinical factors predictive of an in-flight oxygen requirement from a retrospective review of hypoxia challenge tests (inhalation of 14–15% oxygen for 20 minutes) in infants referred for fitness to fly assessment. Methods: Data from 47 infants (median corrected age 1.4 months) with a history of neonatal lung disease but not receiving supplemental oxygen at the time of hypoxia testing are reported. The neonatal and current clinical information of the infants were analysed in terms of their ability to predict the hypoxia test results. Results: Thirty eight infants (81%) desaturated below 85% and warranted prescription of supplemental in-flight oxygen. Baseline oxygen saturation was >95% in all infants. Age at the time of the hypoxia test, either postmenstrual or corrected, significantly predicted the outcome of the hypoxia test (odds ratio 0.82; 95% confidence intervals 0.62 to 0.95; p = 0.005). Children passing the hypoxia test were significantly older than those requiring in-flight oxygen (median corrected age (10–90th centiles) 12.7 (3.0–43.4) v 0 (−0.9–10.9) months; p<0.0001). Conclusions: A high proportion of ex-preterm infants not currently requiring supplemental oxygen referred for fitness-to-fly assessment and less than 12 months corrected age are at a high risk of requiring in-flight oxygen. Referral of this patient group for fitness to fly assessment including a hypoxia test may be indicated.

Response to: Bacterial co-infection and the interpretation of immunological data from BAL fluid specimens in severe RSV bronchiolitis (Thorax 2006;61:1098)

Commercial aircrafts cruise between 9150 and 13000 m above sea level, with a cabin pressure equivalent to 1530–2440 m at which passengers breathe the equivalent of 15–17% of fractional inspired oxygen (FiO2) at sea level. British Thoracic Society recommendations for passengers with chronic respiratory disorders planning air travel1 suggest that infants and young children unable to perform spirometry, with a history of neonatal respiratory disease consult a paediatrician and a hypoxia test be considered. The recommended hypoxia test method in young children is to place the child in a body plethysmograph while seated on the parent’s lap and introduce nitrogen until FiO2 equals 15%. This method relies on equipment not readily available outside the tertiary hospital setting. We have reported a review of hypoxia testing in …

Respiratory function and symptoms in young preterm children in the contemporary era

To determine the relationships between respiratory symptoms, lung function, and neonatal events in young preterm children.Summary Objective To determine the relationships between respiratory symptoms, lung function, and neonatal events in young preterm children. Methods Preterm children (<32 w gestation), classified as bronchopulmonary dysplasia (BPD) or non-BPD, and healthy term controls were studied. Lung function was measured by forced oscillation technique (respiratory resistance [Rrs] and reactance [Xrs]) and spirometry. Respiratory symptom questionnaires were administered. Results One hundred and fifty children (74 BPD, 44 non-BPD, 32 controls) 4–8 years were studied. Lung function (median Z-score [10,90th centile]) was significantly impaired in preterm children compared to controls for FVC (0.00 [−1.18, 1.76], 0.69 [−0.17,1.86]), FEV1 (−0.44 [−1.94, 1.11], 0.49 [−0.83, 2.51]), Xrs (−1.26 [−3.31, 0.11], −0.11 [−0.97, 0.73]), and Rrs (0.55 [−0.48, 1.82], 0.28 [−0.99, 0.96]). Only Xrs differed between the BPD and non-BPD (−1.51 [−3.59, −0.41], −0.89 [−2.64, 0.52]). The prevalence of recent respiratory symptoms (range: 32–36%) did not differ between BPD and non-BPD children. Supplemental O2 in hospital was positively associated with worsening Xrs and FEV1. Conclusion Preterm children have worse lung function than healthy controls. Only respiratory reactance differentiated between preterm children with and without BPD and was influenced by days of O2 in hospital. Pediatr Pulmonol. 2016; 9999:1–9.

Determining the time to maximal bronchodilator response in asthmatic children

Background. The interval between bronchodilator administration and post-bronchodilator lung function testing is critical for accurate interpretation of the bronchodilator response. The time course of this response in children is not well documented. We aimed to document the time taken to achieve maximal lung function following salbutamol inhalation. Methods. Eighteen asthmatic children between 7 and 18 years of age with a history of bronchodilator responsiveness were recruited. Spirometry was performed before and at 0, 10, 15, 20, 40, 60, and 90 minutes after salbutamol inhalation 600 μ g (Ventolin; GlaxoSmithKline) via a spacer (Volumatic; GlaxoSmithKline). Results. Spirometric indices significantly increased after salbutamol inhalation (p < 0.001). The group median time to maximal response in forced expiratory volume in 1 second (FEV1) was 17.5 (10–60: 10th–90th centiles) minutes after salbutamol. The magnitude of group response in FEV1 was significantly higher at 15 and 20 minutes than at 0 and 10 minutes post-salbutamol inhalation (repeat measures analysis of variance [ANOVA] on ranks; p < 0.05). Conclusion. We conclude that a minimal interval of 20 minutes, before re-testing spirometry, is required to document the maximal response to bronchodilators in the majority of asthmatic children.

Characterization of Maximal Respiratory Pressures in Healthy Children

Background: Measurements of maximal voluntary inspiratory (P<smlcap>i</smlcap>_max) and expiratory (P<smlcap>e</smlcap>_max) pressures are used in the management of respiratory muscle disease. There is little data on the appropriate reference range, success rates, or repeatability of P<smlcap>i</smlcap>_max and P<smlcap>e</smlcap>_max in children or on methodological factors affecting test outcomes. Objectives: To determine P<smlcap>i</smlcap>_max and P<smlcap>e</smlcap>_max in healthy children and examine which published reference equations are best suited to a contemporary population. Secondary objectives were to assess within-test repeatability and the influence of lung volumes on P<smlcap>i</smlcap>_max and P<smlcap>e</smlcap>_max. Methods: Healthy children were prospectively recruited from the community on a volunteer basis and underwent spirometry, static lung volumes, and P<smlcap>i</smlcap>_max and P<smlcap>e</smlcap>_max testing. Results: Acceptable and repeatable (to within 20%) P<smlcap>i</smlcap>_max and P<smlcap>e</smlcap>_max were obtained in 156 children, with 105 (67%) children performing both P<smlcap>i</smlcap>_max and P<smlcap>e</smlcap>_max measurements to within 10% repeatability. The reference equations of Wilson et al. [Thorax 1984;39:535–538] best matched our healthy Caucasian children. There was an inverse relationship between P<smlcap>i</smlcap>_max and the percent of total lung capacity (TLC) at which the measurement was obtained (beta coefficient –0.96; 95% CI –1.52 to –0.39; p = 0.001), whereas at lung volumes of >80% TLC P<smlcap>e</smlcap>_max was independent of lung volume (p = 0.26). Conclusion: We demonstrated that the Wilson et al. [Thorax 1984;39:535–538] reference ranges are most suited for contemporary Caucasian Australasian children. However, robust multiethnic reference equations for maximal respiratory pressures are required. This study suggests that 10% within-test repeatability criteria are feasible in clinical practice, and that the use of lung volume measurements will improve the quality of maximal respiratory pressure measurements.

Evaluating hypoxia during air travel in healthy infants

Up to a third of ex-preterm infants flying near term exhibit pulse oxygen saturation (SpO2) of less than 85% during air travel. A hypoxia challenge test (HCT) is recommended to evaluate the requirement for in-flight supplemental O2. The validity of the HCT in healthy, term infants has not been reported. This study aimed to characterise the in-flight hypoxia response and the accuracy of the HCT to predict this response in healthy, term infants in the first year of life. Infants (n=24: (15 male)) underwent a HCT prior to commercial air travel during which parents monitored SpO2. Thirty-two flights were undertaken with six infants completing multiple flights. The median in-flight SpO2 nadir was 87% and significantly lower than the HCT SpO2 nadir (92%: p<0.001). Infants on seven flights recorded SpO2<85% with one infant recording a HCT with a SpO2 less than 85%. There was marked variability in the in-flight SpO2 in the six infants who undertook multiple flights, and for three of these infants, the SpO2 nadir was both above and below 85%. We report that in healthy term infants an in-flight SpO2 below 85% is common and can vary considerably between flights and that the HCT poorly predicts the risk of in-flight hypoxia (SpO2<85%). As it is common for healthy term infants to have SpO2 less than 85% during air travel further research is needed to clarify whether this is an appropriate cut-off in this age group.

Contents Vol. 84, 2012

J. Hammer, Basel F.J.F. Herth, Heidelberg J. Johnston, Vancouver, B.C. C. Kroegel, Jena F. Kummer, Vienna P.N. Mathur, Indianapolis, Ind. M. Miravitlles, Barcelona J. Müller-Quernheim, Freiburg L.P. Nicod, Lausanne M. Noppen, Brussels D. Olivieri, Parma C. Page, London W. Randerath, Solingen S. Siddiqui, Leicester T. Terashima, Ichikawa O.S. Usmani, London S. van Eeden, Vancouver, B.C. K. Yasufuku, Toronto, Ont. Official Journal of