Altered breathing mechanics and ventilatory response during exercise in children born extremely preterm.
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.
Faculty of Medicine and Dentistry, Departments of Pediatrics, University of Alberta, Edmonton, Alberta, Canada Faculty of Medicine and Dentistry, Women & Children's Health Research Institute, University of Alberta, Edmonton, Alberta, Canada.
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http://orcid.org/0000-0001-7994-9910
JE
MacLean
Faculty of Medicine and Dentistry, Departments of Pediatrics, University of Alberta, Edmonton, Alberta, Canada.
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K
DeHaan
Faculty of Medicine and Dentistry, Departments of Medicine, University of Alberta, Edmonton, Alberta, Canada.
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D
Fuhr
Faculty of Medicine and Dentistry, Departments of Pediatrics, University of Alberta, Edmonton, Alberta, Canada Faculty of Medicine and Dentistry, Women & Children's Health Research Institute, University of Alberta, Edmonton, Alberta, Canada.
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Hariharan
Faculty of Medicine and Dentistry, Departments of Pediatrics, University of Alberta, Edmonton, Alberta, Canada Faculty of Medicine and Dentistry, Women & Children's Health Research Institute, University of Alberta, Edmonton, Alberta, Canada.
B
B
Kamstra
Department of Pediatrics, University of Calgary, Calgary, Alberta, Canada.
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Hendson
Faculty of Medicine and Dentistry, Departments of Pediatrics, University of Alberta, Edmonton, Alberta, Canada Faculty of Medicine and Dentistry, Women & Children's Health Research Institute, University of Alberta, Edmonton, Alberta, Canada.
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Adatia
Faculty of Medicine and Dentistry, Departments of Pediatrics, University of Alberta, Edmonton, Alberta, Canada.
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C
Majaesic
Department of Human Physiology, University of Oregon, Eugene, Oregon, USA.
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Lovering
Faculty of Medicine and Dentistry, Biomedical Engineering, University of Alberta, Edmonton, Alberta, Canada.
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RB
Thompson
Faculty of Social Work, University of Calgary, Calgary, Alberta, Canada.
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Nicholas
Department of Pediatrics, University of Ottawa, Ottawa, Ontario, Canada.
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B
Thebaud
Faculty of Medicine and Dentistry, Women & Children's Health Research Institute, University of Alberta, Edmonton, Alberta, Canada.
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Stickland
D001997:Bronchopulmonary Dysplasia / Q000503:physiopathology*; D002170:Canada; D002648:Child; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006801:Humans; D062071:Infant, Extremely Premature / Q000502:physiology*; D008297:Male; D012129:Respiratory Function Tests; D015656:Respiratory Mechanics / Q000502:physiology*
Exercise; Lung Physiology; Paediatric Lung Disaese