Pulmonary function in children who were on long-term mechanical ventilation due to neonatal respiratory disease

Context

Children with a history of neonatal respiratory disease that required mechanical ventilation, who develop subsequent bronchopulmonary dysplasia, often have abnormal pulmonary function. The extent to which the neonatal respiratory disease alone is involved is not clear.

Objective

To evaluate the association between neonatal respiratory disease without bronchopulmonary dysplasia on discharge and pulmonary function later in childhood.

Design

Case–control study.

Setting

Ambulatory follow-up of former intensive care patients at a university medical centre.

Participants

Eighteen children aged 11–15 years with a history of neonatal respiratory disease were randomly recruited, regardless of gestational age or cause of disease. Inclusion criteria: mechanical ventilation for >14 days; high inspired oxygen fraction for >2 days (FiO₂ > 0.4). Exclusion criteria: presence of bronchopulmonary dysplasia or other acute or chronic pulmonary disease at the time of this investigation. Eighteen controls matched for age, sex and height were recruited from children of the hospital staff. All were healthy at birth and had no pulmonary disease at the time of this investigation. All parents gave informed consent.

Pulmonary function tests

Vital capacity (VC); forced expiratory volume in the first second (FEV₁) with and without challenge by the bronchoconstrictor methacholine; diffusing capacity (D_LCO); airway resistance (Rt) with and without methacholine challenge; and thoracic gas volume (TGV).

Main outcome measures

Variables of pulmonary function in the cases. Differences between the cases and controls were compared using the paired-sample t-test.

Results

Both FEV₁ and Rt differed significantly (P < 0.01) between children who had had respiratory disease as neonates (cases) and controls. There were no significant differences in VC, D_LCO and TGV (Table).

Differences in VC and FEV₁ between cases and controls after methacholine challenge were not significant; however, this analysis is of limited value because only eight or nine matched pairs underwent these tests.

Conclusion

A mild degree of airway obstruction is apparent in children 11 to 15 years after neonatal respiratory disease, even in the absence of bronchopulmonary dysplasia or other pulmonary disease.

Table. Pulmonary function tests: mean ± standard deviation