Exercise in children with BPD: Venyilation and cardiac output

Purpose: Previous reports demonstrated slightly lower maximal aerobic capacity (peak VO₂) in children with (BPD) bronchopulmonary dysplasia and hyaline membrane disease (HMD)-children whose pulmonary function tests reveal an obstructive pattern. To elaborate cardiopulmonary adaptations to exercise in this population, a group of children who had previously been enrolled in the high frequency ventilation trial in 1986-87 was studied 9 yr later. Methods: All subjects performed incremental exercise testing to exhaustion, and some later performed exercise at 50% of maximum work rate with sampling of arterialized capillary blood in order to measure cardiac output (indirect [CO₂] Fick) and dead space. Lean body mass (LBM) was computed based on triceps and subscapular skinfold thicknesses. Children who were born prematurely were compared to a group of healthy matched control children (CNT). There were 17 CNT (7 male), 17 children with BPD (9 male), and 15 who had HMD only (9 male). Submaximal exercise with blood sampling was done by 9 BPD, 6 HMD, and 9 controls. Results: are shown in the table. The first 4 columns show maximal exercise results, last 2 columns show sub-maximal test data. V̇O₂ W HR AT V̇_E MVV SV V_D CNT 46 90 196 29 .82 47 3.9 BPD 40^† 79* 196 28 .76 42 3.4 HMD 41^† 77* 195 29 .74 47 4.2 Units: VO₂ (ml/kg/min), Work (watts), HR (bpm), AT-anaerobic threshold (ml/kg/min), MVV=35(FEV₁), SV (ml), V_D (ml/kg) ^†p=.05 *p<.05, compared with controls Stepwise logistic regression of peak V̇O₂ on LBM and %predicted FEV₁ showed only LBM was a statistically significant predictor (r²=.59). Conclusion: Children who had HMD, regardless of whether or not they developed BPD, have lower maximal aerobic power than matched controls, for reasons other than compromised cardiac or ventilatory performance.