Thorax 60:652-658 doi:10.1136/thx.2004.034421
  • Paediatric lung disease

A new method for objective identification and measurement of airway lumen in paediatric flexible videobronchoscopy

  1. I B Masters1,2,
  2. M M Eastburn3,
  3. R Wootton4,
  4. R S Ware5,
  5. P W Francis1,2,
  6. P V Zimmerman6,
  7. A B Chang1,2
  1. 1Department of Respiratory Medicine, Royal Children’s Hospital, Herston 4029, Brisbane, Australia
  2. 2School of Medicine, Discipline of Paediatric and Child Health, University of Queensland, Herston 4029, Brisbane, Australia
  3. 3University of Queensland, Department of Information Technology and Electrical Engineering, St Lucia 4072, Brisbane, Australia
  4. 4University of Queensland Centre for Online Health, Royal Children’s Hospital, Herston 4029, Brisbane, Australia
  5. 5School of Population Health, The University of Queensland, Herston 4006, Brisbane, Australia
  6. 6Department of Thoracic Medicine, The Prince Charles Hospital, Chermside 4032, Brisbane, Australia
  1. Correspondence to:
    Dr I B Masters
    Department of Respiratory Medicine, Royal Children’s Hospital, Herston 4029, Brisbane, Australia;
  • Received 6 September 2004
  • Accepted 17 March 2005


Background: Accurate measurements of airway and lesion dimensions are important to the developmental progress of paediatric bronchoscopy. The malacia disorders are an important cause of respiratory morbidity in children, but no methods are currently available to measure these lesions or the airway lumen accurately. A new measurement technique is described here.

Methods: The magnification power of a paediatric videobronchoscope was defined and a simple and user friendly computer based program (Image J) was used to develop an objective technique (colour histogram mode technique, CHMT) for measurement of the airway lumen.

Results: In vivo intra-observer and inter-observer repeatability coefficients for repeated area measurements from 28 images using the Bland-Altman method were 0.9 mm2 and 1.6 mm2, respectively. The average intraclass correlation coefficient for repeated measurements of area was 0.93. In vitro validation measurements using a 2 mm diameter tube resolved radii measurements to within 0.1 mm (coefficient of variability 8%). An “acceptable result” was defined in 92% of 734 images completed with the CHMT alone and 8% with its modification. The success rate for two of three images being within 10% of each other’s area was 100%. Measurements of cricoid cross sectional areas from 116 patients compared with expected airway areas for age derived from endotracheal tube sizes were comparable.

Conclusions: The CHMT method of identifying and measuring airway dimensions is objective, accurate, and versatile and, as such, is important to the future development of flexible videobronchoscopy.