FACTORS LIMITING EXERCISE PERFORMANCE IN LONG-TERM SURVIVORS OF BRONCHOPULMONARY DYSPLASIA

The long-term impairment of pulmonary function during exercise was ass essed in 12 children, aged 6 to 12 yr, who developed BPD after prematu rity (gestational age 30 +/- 2 wk [mean +/- SD] and birth weight 1,400 +/- 335 g) and 16 age-, sex-, and physical activity-matched healthy c hildren born at term, who served as controls. The children performed p ulmonary function tests at rest and a maximal stepwise exercise on a t readmill. Oxygen consumption (VO2), carbon dioxide output (VCO2), and minute ventilation (VE) were monitored during the run. Baseline mean s pirometric values (% of predicted) were in the normal range for both g roups but were lower in BPD children with respect to control children (p < 0.05). At rest, arterial oxygen saturation (Sa(O2)) was greater t han or equal to 98% in all BPD children, but at peak exercise, 4 of th em had a Sa(O2) fall greater than or equal to 4%. The postexercise FEV (1) fall, with respect to the baseline, was 8 +/- 6% in BPD and 2 +/- 1% in control children (p < 0.01). Maximum VO2 and VE were significant ly lower in BPD children with respect to the control group (25.2 +/- 1 0.3 versus 37.1 +/- 10.4 ml/min/kg and 20.8 +/- 9.4 versus 30.7 +/- 7. 9 L/min, respectively, both p < 0.01). Also, at submaximal levels of e xercise dynamic, VO2 and VE responses were significantly lower in the BPD group (ANOVA, p < 0.001), with a ventilatory pattern characterized by lower tidal volumes. Anaerobic threshold was 20.6 +/- 9 in BPD and 28.8 +/- 8.6 ml O-2/min/kg in healthy children (p < 0.05). Running ti me was 6.1 +/- 1.3 min in BPD and 7.9 +/- 2.6 min in control children (p < 0.05). No difference was found in maximal heart rate. We conclude that asymptomatic school-aged survivors of BPD show evidence of strik ing disturbances in ventilatory response to exercise and reduced aerob ic capacity compared with healthy children, even if pulmonary function at rest is only slightly impaired.