Lung function after neonatal respiratory distress syndrome.

Functional residual capacity (FRC), dynamic lung compliance (CLdyn) and lung resistance (RL) were measured in a group of 51 healthy children aged 18 months to 6 years (group A) and in a group of 69 survivors of the respiratory distress syndrome (RDS) of the same age (group B). Forty-four per cent of the latter had clinical and radiological abnormalities. In the healthy children significant correlations were found between FRC and height (p less than 0.01), CLdyn and height (P less than 0.01) and CLdyn and FRC (p less than 0.01) but a poor correlation existed between RL and height (p greater than 0.05). There was no significant difference between groups A and B in the slopes of the regression lines for FRC, CLdyn and RL against height, but the intercept for the regression lines relating to CLdyn and RL was lower in group B than in group A. Group B was divided into two subgroups according to the length of exposure to artificial ventilation with an FIO2 in excess of 60 %. A lower value for CLdyn was found in the sub-group with the longer exposure (greater than 120 hours) to a high FIO2, suggesting that this is an additional factor in causing lung damage.