title: Pulmonary Gas Exchange and Exercise Capacity in Adults Born Preterm.
abstract: BACKGROUND
  Preterm birth, and its often-required medical interventions, can result in respiratory and gas exchange deficits into childhood. However, the long-term sequelae into adulthood are not well understood.
  
  
  OBJECTIVE
  To determine exercise capacity and pulmonary gas exchange efficiency during exercise in adult survivors of preterm birth.
  
  
  METHODS
  Preterm (n = 14), very low birth weight (<1,500 g) adults (20-23 yr) and term-born, age-matched control subjects (n = 16) performed incremental exercise on a cycle ergometer to volitional exhaustion while breathing one of two oxygen concentrations: normoxia (fraction of inspired oxygen, 0.21) or hypoxia (fraction of inspired oxygen, 0.12).
  
  
  RESULTS
  Ventilation, mixed expired gases, arterial blood gases, power output, and oxygen consumption were measured during rest and exercise. We calculated the alveolar-to-arterial oxygen difference to determine pulmonary gas exchange efficiency. Preterm subjects had lower power output at volitional exhaustion than did control subjects in normoxia (150 ± 10 vs. 180 ± 10 W; P = 0.01), despite similar normoxic oxygen consumption. However, during hypoxic exercise, there was no difference in power output at volitional exhaustion between the two groups (116 ± 10 vs. 135 ± 10 W; P = 0.11). Preterm subjects also exhibited a more acidotic, acid-base balance throughout exercise compared with control subjects. In contrast to other studies, adults born preterm, as a group developed a wider alveolar-to-arterial oxygen difference and lower PaO2 than did control subjects during normoxic but not hypoxic exercise.
  
  
  CONCLUSIONS
  This study demonstrates that pulmonary gas exchange efficiency is lower in some adult survivors of preterm birth during exercise compared with control subjects. The gas exchange inefficiency, when present, is accompanied by low arterial blood oxygen tension. Preterm subjects also exhibit reduced power output. Overall, our findings suggest potential long-term consequences of extreme preterm birth and very low birth weight on cardiopulmonary function.
authors.affiliation: 1 Department of Pediatrics, Critical Care Division and the John Rankin Laboratory of Pulmonary Medicine.
authors.forename: Emily T
authors.initials: ET
authors.lastname: Farrell
authors.affiliation: 1 Department of Pediatrics, Critical Care Division and the John Rankin Laboratory of Pulmonary Medicine.|2 Department of Health and Human Physiology, University of Iowa, Iowa City, Iowa.
authors.forename: Melissa L
authors.initials: ML
authors.lastname: Bates
authors.affiliation: 1 Department of Pediatrics, Critical Care Division and the John Rankin Laboratory of Pulmonary Medicine.
authors.forename: David F
authors.initials: DF
authors.lastname: Pegelow
authors.affiliation: 3 Department of Population Health Sciences.|4 Department of Biostatistics and Medical Informatics.
authors.forename: Mari
authors.initials: M
authors.lastname: Palta
authors.affiliation: 4 Department of Biostatistics and Medical Informatics.
authors.forename: Jens C
authors.initials: JC
authors.lastname: Eickhoff
authors.affiliation: 5 Department of Pulmonary Function, and.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: O'Brien
authors.affiliation: 1 Department of Pediatrics, Critical Care Division and the John Rankin Laboratory of Pulmonary Medicine.|6 Departments of Biomedical Engineering and Kinesiology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin; and.
authors.forename: Marlowe W
authors.initials: MW
authors.lastname: Eldridge
mesh_terms: D000328:Adult; D000375:Aging; D001784:Blood Gas Analysis; D016022:Case-Control Studies; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology; D007231:Infant, Newborn; D019102:Infant, Very Low Birth Weight / Q000254:growth & development*; D008297:Male; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption; D047928:Premature Birth; D011659:Pulmonary Gas Exchange / Q000502:physiology*; D055815:Young Adult
chemical_list: D010100:Oxygen
keywords: alveolar–arterial oxygen difference; prematurity; pulmonary gas exchange