Ventilatory and sensory responses in adult survivors of preterm birth and bronchopulmonary dysplasia with reduced exercise capacity

Rationale: 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.

Objectives: 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.

Measurements and Main Results: During exercise at 90% of peak V O₂ (V _O2peak), inspiratory reserve volume decreased to z0.5 L in all groups, but this occurred at significantly lower absolute workloads and V E in ex-preterm subjects with and without BPD compared with full-term control subjects. Severe dyspnea was present and similar at comparable V 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 V _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.