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


OBJECTIVE
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.


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.
Narang
Indra
I
Division of Respiratory Medicine, Hospital for Sick Children, Toronto, Canada. indra.narang@sickkids.ca
Bush
Andrew
A
Rosenthal
Mark
M
D001724:Birth Weight; D001783:Blood Flow Velocity / Q000502:physiology; D002302:Cardiac Output / Q000502:physiology; D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007385:Intermittent Positive-Pressure Ventilation; D008168:Lung / Q000098:blood supply*; D008297:Male; D013058:Mass Spectrometry; D010100:Oxygen / Q000097:blood; D010102:Oxygen Inhalation Therapy; D011659:Pulmonary Gas Exchange / Q000502:physiology*; D012016:Reference Values; D012127:Respiratory Distress Syndrome, Newborn / Q000503:physiopathology*; D055815:Young Adult
D010100:Oxygen