Article Text


Respiratory physiology and oxygen therapy
P38 The Impact of Ethnicity on Specific Airways Resistance (sRaw) in Children
  1. J Kirkby,
  2. R Bonner,
  3. S Lum,
  4. S Sonnappa,
  5. J Stocks
  1. UCL, Institute of Child Health, London, UK


Introduction Plethysmographic Specific Airways Resistance (sRaw), which can be measured during tidal breathing without need for airway occlusion.[1] has been shown to discriminate between young healthy children and those with lung disease. Recent recommendations and reference data were, however, based on data from White children.[2] This could potentially bias interpretation if applied to children of other ethnicities. Nevertheless, since ethnic differences in lung and airway function have been shown to be proportional,[3] and since sRaw is internally adjusted for differences in resting lung volume, we hypothesised that there would be no ethnic differences in sRaw.

Aim To compare sRaw between healthy Black and healthy White children of similar age.

Methods Fifty-six healthy Black children (64% male, mean (SD) age: 8.3(1.1) years) and 148 healthy White children (50% male, mean (SD) age: 7.3(1.4) years) underwent sRaw measurements in accordance with recent recommendations.[2] Results were expressed as Z-Scores to adjust for height, sex and age.[2] Paired t-tests were used to determine the impact of ethnicity on sRaw.

Results There were no significant differences in sRaw between healthy Black children and healthy White children (p=0.22). The mean (95% CI) difference (Black-White) for specific effective airways resistance (sReff)[2] was –0.2 Z-Scores (0.5; 0.1) (figure 1).

Abstract P38 Figure 1

Comparison of sReff Z-Scores in healthy White and Black children (Black lines denotes mean±SD)

Conclusion Since ethnic differences in sRaw do not occur, published sRaw reference equations derived from White children should be equally applicable when assessing Black children with lung disease.


  1. Dab & Alexander, Pediatr Res, 1976.

  2. Kirkby, ERJ, 2010.

  3. Quanjer ERJ 2012.

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