Substrate mobilization: a new hypothesis for the aetiology of the idiopathic respiratory distress syndrome.

This hypothesis for the aetiology of the idiopathic respiratory distress syndrome of the newborn (IRDS) proposes that, although the aetiology is multifactorial, the factor of prime importance is the mobilization of substrate for surfactant synthesis. All factors known to influence the incidence, treatment, and prognosis of the IRDS can be shown to be associated with the mobilization of substrate and thereafter its continued availability for the synthesis of adequate surfactant. Thus factors which promote an antenatal increase in the breakdown of energy stores will be associated with a reduced incidence of the IRDS. On the other hand, despite adequate mobilization, factors associated with a lack of substrate secondary to poor transport of substrate, a reduction in pulmonary circulation or an alteration in fetal or neonatal metabolism which involves an increased utilization of substrate to provide energy, will be associated with an increased incidence of the IRDS.