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Altered breathing mechanics and ventilatory response during exercise in children born extremely preterm
  1. J E MacLean1,2,
  2. K DeHaan1,
  3. D Fuhr3,
  4. S Hariharan1,2,
  5. B Kamstra1,2,
  6. L Hendson4,
  7. I Adatia1,2,
  8. C Majaesic1,
  9. A T Lovering5,
  10. R B Thompson6,
  11. D Nicholas7,
  12. B Thebaud8,
  13. M K Stickland2
  1. 1Faculty of Medicine and Dentistry, Departments of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
  2. 2Faculty of Medicine and Dentistry, Women & Children's Health Research Institute, University of Alberta, Edmonton, Alberta, Canada
  3. 3Faculty of Medicine and Dentistry, Departments of Medicine, University of Alberta, Edmonton, Alberta, Canada
  4. 4Department of Pediatrics, University of Calgary, Calgary, Alberta, Canada
  5. 5Department of Human Physiology, University of Oregon, Eugene, Oregon, USA
  6. 6Faculty of Medicine and Dentistry, Biomedical Engineering, University of Alberta, Edmonton, Alberta, Canada
  7. 7Faculty of Social Work, University of Calgary, Calgary, Alberta, Canada
  8. 8Department of Pediatrics, University of Ottawa, Ottawa, Ontario, Canada
  1. Correspondence to Dr Joanna E MacLean, Division of Respiratory Medicine, Department of Pediatrics, University of Alberta, 4-590 Edmonton Clinic Health Academy, 11405 87th Avenue, Edmonton, Alberta, Canada, T6G 1C9; joanna.maclean{at}


Background Extreme preterm birth confers risk of long-term impairments in lung function and exercise capacity. There are limited data on the factors contributing to exercise limitation following extreme preterm birth. This study examined respiratory mechanics and ventilatory response during exercise in a large cohort of children born extremely preterm (EP).

Methods This cohort study included children 8–12 years of age who were born EP (≤28 weeks gestation) between 1997 and 2004 and treated in a large regionalised neonatal intensive care unit in western Canada. EP children were divided into no/mild bronchopulmonary dysplasia (BPD) (ie, supplementary oxygen or ventilation ceased before 36 weeks gestational age; n=53) and moderate/severe BPD (ie, continued supplementary oxygen or ventilation at 36 weeks gestational age; n=50). Age-matched control children (n=65) were born at full term. All children attempted lung function and cardiopulmonary exercise testing measurements.

Results Compared with control children, EP children had lower airway flows and diffusion capacity but preserved total lung capacity. Children with moderate/severe BPD had evidence of gas trapping relative to other groups. The mean difference in exercise capacity (as measured by oxygen uptake (VO2)% predicted) in children with moderate/severe BPD was −18±5% and −14±5.0% below children with no/mild BPD and control children, respectively. Children with moderate/severe BPD demonstrated a potentiated ventilatory response and greater prevalence of expiratory flow limitation during exercise compared with other groups. Resting lung function did not correlate with exercise capacity.

Conclusions Expiratory flow limitation and an exaggerated ventilatory response contribute to respiratory limitation to exercise in children born EP with moderate/severe BPD.

  • Exercise
  • Lung Physiology
  • Paediatric Lung Disaese

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:

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  • Contributors JEM, BK, LH, IA, CM, ATL, RBT, DN, BT and MKS contributed to the designed the study. JEM, KD, DF, SH, BK and IA contributed to data acquisition. JEM and KD contributed to data analysis. JEM, KD, DF, LH, IA, ATL and MKS contributed to interpretation of the work. All authors contributed to revision of the manuscript, provided final approval of the manuscript and are accountable for all aspects of this work.

  • Funding Alberta Health Services (AHS) Emerging Research Team Grant.

  • Competing interests None declared.

  • Ethics approval University of Alberta Human Research Ethics Board.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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