Gas transfer and pulmonary blood flow at rest and during exercise in adults 21 years after preterm birth

Am J Respir Crit Care Med. 2009 Aug 15;180(4):339-45. doi: 10.1164/rccm.200809-1523OC. Epub 2009 Jun 4.


Rationale: After preterm birth, limited data exist in adulthood regarding alveolar-capillary growth and exercise capacity. Gas transfer at rest through exercise is a noninvasive measure of alveolar-capillary development.

Objectives: To determine exercise capacity and gas transfer at rest and during exercise in ex-preterm adults.

Methods: Ex-preterm subjects (n = 60; median gestation, 31.5 wk) recruited at birth underwent exercise testing at 21 years of age and were contemporaneously compared with 50 healthy control subjects.

Measurements and main results: Subjects exercised on a cycle ergometer, and measurements of heart rate (HR), FRC, effective pulmonary blood flow (Qpeff), stroke volume (SV), DL(CO), Vo(2), arteriovenous oxygen difference (AVO), transit time (TT), respiratory rate (Rf), Vco(2), Ve, Vt, and respiratory quotient (RQ) were made using a respiratory mass spectrometer. In the index study group and control subjects, the median DL(CO) (mmol/min/kPa/m(2)) at rest was 4.33 (95% confidence interval [CI], 4.18-4.62) and 4.75 (95% CI, 4.50-5.10), respectively (P = 0.01), and the median Qpeff (L/min/m(2)) at rest was 3.26 (95% CI, 3.16-3.49) and 3.59 (95% CI, 3.43-3.81), respectively (P = 0.04). Qpeff and DL(CO) values normalized during exercise but were reduced and lower than controls after a recovery period. No significant differences were found in exercise capacity between the groups.

Conclusions: The data suggest a long-term effect of premature delivery on resting cardiac output and gas transfer, not due to abnormal cardiac or pulmonary function and with no evidence of exercise limitation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Birth Weight
  • Blood Flow Velocity / physiology
  • Cardiac Output / physiology
  • Exercise Test*
  • Female
  • Follow-Up Studies
  • Gestational Age
  • Humans
  • Infant, Newborn
  • Intermittent Positive-Pressure Ventilation
  • Lung / blood supply*
  • Male
  • Mass Spectrometry
  • Oxygen / blood
  • Oxygen Inhalation Therapy
  • Pulmonary Gas Exchange / physiology*
  • Reference Values
  • Respiratory Distress Syndrome, Newborn / physiopathology*
  • Young Adult


  • Oxygen