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Few studies exist investigating lung function trajectories of those born preterm, however growing evidence suggests some individuals experience increasing airway obstruction throughout life. Here we use the studies identified in a recent systematic review to provide the first meta-analysis investigating the impact of preterm birth on airway obstruction measured by the FEV1/FVC ratio.Cohorts were included for analysis if they reported FEV1/FVC in survivors of preterm birth (55 cohorts were eligible, 35 of which defined groups with bronchopulmonary dysplasia (BPD). Compared to control populations born at term, lower values of FEV1/FVC were seen in all individuals born preterm (SMD −0.56), with greater differences seen in those with BPD (SMD −0.87) than those without BPD (SMD −0.45). Meta-regression identified age as a significant predictor of FEV1/FVC in those with BPD with the FEV1/FVC ratio moving −0.04 SDs away from the term control population for every year of increased age.Survivors of preterm birth have significantly increased airway obstruction compared to those born at term with larger differences in those with BPD. Increased age is associated with a decline in FEV1/FVC values suggesting increased airway obstruction over the life course.

IntroductionNon-invasive measurement of respiratory impedance by oscillometry can be used in young children from 3 years and those unable to perform forced respiratory manoeuvres. It can discriminate between healthy children and those with respiratory disease. However, its clinical application is limited by the lack of reference data for African paediatric populations.AimTo develop reference equations for oscillometry outcomes in South African children and adolescents.MethodsHealthy subjects, enrolled in the Drakenstein Child Health Study, HIV uninfected adolescents in the Cape Town Adolescent Antiretroviral Cohort and healthy children attending surgical outpatient clinics at Red Cross War Memorial Children's Hospital were measured with conventional spectral (6–32 Hz) and intra-breath (10 Hz) oscillometry. Stepwise linear regression was used to assess the relationship between respiratory variables and anthropometric predictors (height, sex, ancestry) to generate reference equations.ResultsA total of 692 subjects, 48.4% female, median age of 5.2 years (range: 3–17 years) were included. The median interquartile range (IQR) for weight for age z-score and height for age z-score was −0.42 (−1.11; 0.35) and −0.65 (−1.43; 0.35), respectively. Stepwise regression demonstrated that all the variables were significantly dependent on height only. Comparison to previous reference data indicated slightly higher resistance and lower compliance values in the smallest children.ConclusionWe established the first respiratory oscillometry reference equations for African children and adolescents, which will facilitate use in early identification and management of respiratory disease. Our results suggest differences in oscillometry measures by ancestry but also highlight the lack of standardisation in methodology.

User verification of device accuracy using test loads should encompass the expected range of Zrs to be tested; this letter clarifies the definition of Zrs ranges of the population being tested. Manufacturers should report accuracy of both Rrs and Xrs.https://bit.ly/2ZrnOCD

To the Editor : The mannitol challenge is an indirect challenge that increases airway surface liquid osmolality resulting in bronchoconstriction [1, 2]. Mannitol challenge tests are used clinically to diagnose asthma and, in particular, exercise-induced broncoconstriction (EIB) in adults and children above 6 years of age [3]. To date, mannitol has not been used as a challenge agent in children under 6 years of age and the feasibility and safety of its use in this age group is unknown. The assessment of bronchial responsiveness in young children is difficult and limited by the cooperation of the child. The standardisation of lung function tests suitable for use in young children, such as the interrupter technique or the forced oscillation technique (FOT), provide an opportunity to assist in the assessment of bronchial responsiveness in young children and a variety of challenge tests using FOT have been reported in young children [4]. The aim of this preliminary study was to assess the feasibility and safety of the mannitol challenge test in young children using the FOT as the objective outcome measure. 20 children aged 3–7 years were recruited; 10 of these children were healthy and 10 children had a history of parentally reported exercise-induced symptoms (EIS) in the past year. The mannitol challenge test (Aridol; Pharmaxis, Frenchs Forest, Australia) was performed as previously published [2], with the exceptions that the respiratory resistance at 8 Hz ( R rs8) from the FOT was used as the primary outcome and the definition of a positive response was altered, as detailed below. Prior to …