Ventilatory and sensory responses in adult survivors of preterm birth and bronchopulmonary dysplasia with reduced exercise capacity.
BACKGROUND
Adults born very to extremely preterm, with or without bronchopulmonary dysplasia (BPD), have obstructive lung disease, but it is unknown whether this results in respiratory limitations, such as mechanical constraints to Vt expansion during exercise leading to intolerable dyspnea and reduced exercise tolerance, as it does in patients with chronic obstructive pulmonary disease.


OBJECTIVE
To test the hypothesis that adult survivors of preterm birth (≤32 wk gestational age) with (n = 20) and without BPD (n = 15) with reduced exercise capacity demonstrate clinically important respiratory limitations at near-maximal exercise compared with full-term control subjects (n = 20).


METHODS
Detailed ventilatory and sensory measurements were made before and during exercise on all patients in the three study groups.


RESULTS
During exercise at 90% of peak [Formula: see text]o2 ([Formula: see text]o2peak), inspiratory reserve volume decreased to ∼0.5 L in all groups, but this occurred at significantly lower absolute workloads and [Formula: see text]e in ex-preterm subjects with and without BPD compared with full-term control subjects. Severe dyspnea was present and similar at comparable [Formula: see text]e between all groups, but leg discomfort at comparable workloads was greater in ex-preterm subjects with and without BPD compared with control subjects. At 50 to 90% of [Formula: see text]o2peak, exercise-induced expiratory flow limitation was significantly greater in ex-preterm subjects with BPD compared with ex-preterm subjects without BPD and control subjects. The degree of expiratory flow limitation in ex-preterm subjects with and without BPD was significantly related to neonatal O2 therapy duration.


CONCLUSIONS
Severe dyspnea and leg discomfort associated with critical constraints on Vt expansion may lead to reduced exercise tolerance in adults born very or extremely preterm, whether or not their birth was complicated by BPD and despite differences in expiratory flow limitation. In this regard, adults born very or extremely preterm have respiratory limitations to exercise similar to patients with chronic obstructive pulmonary disease.
1 Department of Human Physiology, University of Oregon, Eugene, Oregon.
Andrew T
AT
Lovering
Jonathan E
JE
Elliott
Steven S
SS
Laurie
Kara M
KM
Beasley
Caitlyn E
CE
Gust
Tyler S
TS
Mangum
Igor M
IM
Gladstone
Joseph W
JW
Duke
D000293:Adolescent; D000328:Adult; D001997:Bronchopulmonary Dysplasia / Q000503:physiopathology*; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology*; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D011247:Pregnancy; D047928:Premature Birth / Q000503:physiopathology*; D012189:Retrospective Studies; D017741:Survivors / Q000706:statistics & numerical data*; D055815:Young Adult
dynamic hyperinflation; ex-preterms; exercise capacity; lung function; mechanical constraints to exercise