Accuracy of Whole-Body Plethysmography Requires Biological Calibration

doi:10.1378/chest.08-1555

Chest

Volume 135, Issue 6, June 2009, Pages 1476-1480

https://doi.org/10.1378/chest.08-1555 Get rights and content

Background

Specific airway resistance (sRaw) measured by whole-body plethysmography in young children is increasingly used in research and clinical practice. The method is precise and feasible. However, there is no available method for calibration of the resistance measure, which raises concern of accuracy. Our aim was to determine the agreement of sRaw measurements in six centers and expand normative sRaw values for nonasthmatic children including these centers.

Method

Identical hardware with different software versions was used at the six centers. Measurements followed a standard operating procedure: (1) seven healthy young children were brought to each of the six centers for sRaw measurements; and (2) 105 healthy preschool children (52 boys; mean age, 5.1 years; interquartile range, 4.3 to 6.0) were recruited locally for sRaw measurements.

Results

(1) The sRaw of the seven-children study group was significantly lower at two centers compared with the other four centers, and one center had significantly higher sRaw than all the other centers (p < 0.05). Error in the factory settings of the software was subsequently discovered in one of the deviating centers. (2) Normative data (105 preschool children) were generated and were without significant difference between centers and independent of height, weight, age, and gender. We subsequently pooled these normative data (105 children) with our previous data from 121 healthy young children (overall mean sRaw, 1.27; SD, 0.25).

Conclusion

Control using biological standards revealed errors in the factory setting and highlights the need for developing methods for verification of resistance measures to assure accuracy. Normative data were subsequently generated. Importantly, other centers using such normative data should first consider proper calibration before applying reference values.

Section snippets

Materials and Methods

The study was approved by the local ethics committee as a quality assurance project and approved by the Danish Data Protection Agency. Parents gave written informed consent.

Results

All seven children completed measurements at each of the six centers. The children were between 4.9 and 6.6 years old (three boys). None of the children had a history of asthma or allergy. Three children had had atopic dermatitis, three had parental atopy, and none had smoking parents.

Lung function measurements differed significantly between centers (Fig 1). sRaw at centers 1 and 2 were significantly lower in all children compared with the other four centers, and center 6 had significantly

Between-Center Variation

sRaw offers a method for clinical monitoring and research during the critical period of growth and development early in life. The method is feasible from the age of 2 years, and the precision is high.1, 2, 3 However, the present study showed that the accuracy of sRaw measurements in young children was flawed due to errors in the factory setting in one center. It is the key message of our study that center effects were seen and could only be explained by differences in the software hidden from

Acknowledgments

We thank all the children and parents who participated in the study. We also thank S. Pedersen, B. Christensen, and T. Duus (Danish Pediatric Asthma Center, Kolding); H. Andreassen and A. K. Thomsen (Pediatric Department, Naestved Hospital); L. Johnsen, H. Niekrenz, and P. O. Schioetz (Danish Pediatric Asthma Center, Aarhus University Hospital, Skejby); K. Mathiesen, L. Klansoe, S. V. Thorsen, S. M. Jensen, and C. B. Pipper (Danish Pediatric Asthma Center, Copenhagen University Hospital,

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The major strength of this study is the close clinical surveillance of the cohort with scheduled visits to our research center from birth till adolescence as well as additional clinic visits in cases of acute lung symptoms. The spirometry and whole-body plethysmography33-36 measurements conducted repetitively at 11 scheduled time points beginning at 1 month of age26,28-31 allowed us to study lung function trajectories in children with asthma who develop exacerbations compared with children without exacerbations, even before the first asthma symptoms and exacerbations emerged. The study design where the COPSAC pediatricians were the families' primary physicians evaluating acute troublesome lung symptoms assured consistency in the diagnostic procedures and treatment of asthma.
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The authors have reported to the ACCP that no significant conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal.org/site/misc/reprints.xhtml).

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Chest

Original ResearchLung FunctionAccuracy of Whole-Body Plethysmography Requires Biological Calibration

Background

Method

Results

Conclusion

Section snippets

Materials and Methods

Results

Between-Center Variation

Acknowledgments

Chest

Lung function measurement in awake young children

Eur Respir J

Specific airway resistance, interrupter resistance, and respiratory impedance in healthy children aged 2–7 years

Pediatr Pulmonol

Observer variability of lung function measurements in 2–6-yr-old children

Eur Respir J

Evaluation of some techniques for measurements of lung function in young children

Dan Med Bull

Original Research
Lung Function
Accuracy of Whole-Body Plethysmography Requires Biological Calibration