Introduction Noninvasive measurement of respiratory impedance by oscillometry can
be used in young children aged 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. The aim of the present study was to develop reference
equations for oscillometry outcomes in South African children and adolescents. Methods
Healthy 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. Results A 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. Conclusion We 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.
