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Original article
New reference ranges for interpreting forced expiratory manoeuvres in infants and implications for clinical interpretation: a multicentre collaboration
  1. Sooky Lum1,
  2. Vassiliki Bountziouka1,
  3. Angela Wade2,
  4. Ah-Fong Hoo1,3,
  5. Jane Kirkby1,3,
  6. Antonio Moreno-Galdo4,
  7. Ines de Mir4,
  8. Olaia Sardon-Prado5,6,
  9. Paula Corcuera-Elosegui5,
  10. Joerg Mattes7,8,
  11. Luis Miguel Borrego9,10,
  12. Gwyneth Davies1,3,
  13. Janet Stocks1
  1. 1Respiratory, Critical Care & Anaesthesia section in IIIP Programme, UCL, Institute of Child Health, London, UK
  2. 2Department of Clinical Epidemiology, Nutrition and Biostatistics Section, UCL, Institute of Child Health, UK
  3. 3Respiratory Medicine, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
  4. 4Paediatric Pulmonology Unit, Hospital Vall d'Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain
  5. 5Division of Paediatric Respiratory Medicine, Donostia University Hospital, San Sebastian, Spain
  6. 6Department of Paediatrics, University of the Basque Country, San Sebastian, Spain
  7. 7School of Medicine and Public Health, University of Newcastle, Newcastle, Australia
  8. 8Department of Paediatric Respiratory & Sleep Medicine, John Hunter Children's Hospital, Newcastle, Australia
  9. 9Centro de Alergia, CUF Descobertas Hospital, Lisbon, Portugal
  10. 10CEDOC, NOVA Medical School, Lisbon, Portugal
  1. Correspondence to Dr Sooky Lum, Respiratory, Critical Care & Anaesthesia Section in IIIP Programme, UCL, Institute of Child Health, 30 Guilford Street, London WC1N 1EH, UK; s.lum{at}


The raised volume rapid thoracoabdominal compression (RVRTC) technique is commonly used to obtain full forced expiratory manoeuvres from infants, but reference equations derived from ‘in-house’ equipment have been shown to be inappropriate for current commercially available devices.

Aim To explore the impact of equipment differences on RVRTC outcomes, derive robust equipment-specific RVRTC reference ranges and investigate their potential clinical impact on data interpretation.

Method RVRTC data from healthy subjects using Jaeger BabyBody or the ‘Respiratory Analysis Software Program, RASP’ systems were collated from four centres internationally. Data were excluded if gestational age <37 weeks or birth weight <2.5 kg. Reference equations for RVRTC outcomes were constructed using the LMS (lambda–mu–sigma) method, and compared with published equations using data from newborn screened infants with cystic fibrosis (CF).

Results RVRTC data from 429 healthy infants (50.3% boys; 88% white infants) on 639 occasions aged 4–118 weeks were available. When plotted against length, flows were significantly higher with RASP than Jaeger, requiring construction of separate equipment-specific regression equations. When comparing results derived from the new equations with those from widely used published equations based on different equipments, discrepancies in forced expiratory volumes and flows of up to 2.5 z-scores were observed, the magnitude of which increased with age. According to published equations, 25% of infants with CF fell below the 95% limits of normal for FEV0.5, compared with only 10% when using the new equations.

Conclusions Use of equipment-specific prediction equations for RVRTC outcomes will enhance interpretation of infant lung function results; particularly during longitudinal follow-up.

  • Respiratory Measurement
  • Paediatric Lung Disaese

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