Conventional vs high frequency ventilation for hyaline membrane disease: Childhood lung function

Purpose: The high frequency ventilation (HFV) trial for hyaline membrane disease (HMD) showed no significant differences in short-term outcome compared with conventional mechanical ventilation (CMV). I hypothesized that lung function testing would also reveal no difference between children ventilated by either method. Methods: Children aged 8-9 years, without developmental delay, who had participated in the Winnipeg cohort of this multicentre trial in 1986-87 were asked to return for lung function tests in a body plethysmograph before and after bronchodilator. The patient population was analysed according to mode of ventilation, and according to a diagnosis of bronchopulmonary dysplasia (BPD) or HMD only. Their results were compared with those of matched controls (CNT). Results: There were 18 (7 male) controls, 17 children with BPD (9 male), and 15 who had HMD only (9 male). Eleven children received HFV and 20 received CMV (1 crossed over). Lung function tests (%predicted) were as follows CNT HMD BPD CMV HFV FVC 97 95 98 97 95 FEV₁ 90 83 87 85 85 FEF₅₀ 86 67* 71* 67* 73* TLC 97 103 107* 105* 107* RV 102 140* 141* 135* 150* RV/TLC 0.23 0.29* 0.29* 0.28* 0.30* D_LCO 109 116 99*^† 106 110 *p <.05 compared with controls; ^†p<.05 compared with HMD patients (protected t test). Seven children (23%) had significant improvement (>10% in FEV₁ or >25% in FEF_25-75) in spirometry post-bronchodilator (2 BPD, 3 HFV). Conclusions: These results show that childhood lung function in prematurely born infants with HMD or BPD is not different in those who received HFV vs CMV. Pulmonary function tests showed a mild obstructive pattern compared with healthy controls, confirming earlier reports in children who had been born prematurely.