Controversies: synthetic or natural surfactant treatment for respiratory distress syndrome? The case for synthetic surfactant.

The choice of surfactant for prophylactic or "rescue" treatment of RDS is dependent on a number of different considerations: a) Randomised controlled trials have shown that natural and synthetic surfactants increase survival whether used prophylactically or as rescue. No statistically significant difference in mortality has been shown when the two types of surfactant have been compared in randomised trials. b) Possible adverse effects of surfactant treatment include: (i) Intraventricular haemorrhage (IVH). Two randomised trials of natural surfactant have shown a significant increase in IVH with natural surfactant treatment. In meta-analyses, IVH has not been significantly reduced despite decreased mortality. Acute changes in cerebral haemodynamics and EEG have been demonstrated following natural surfactant administration. These changes are less marked or absent with synthetic surfactant. (ii) The antigenicity of animal surfactant has not been shown to have clinical consequences. (iii) Prions are infectious particle (resistant to some sterilising techniques) which are responsible for slow encephalopathies, some of which have crossed species barriers. Contamination of bovine surfactant with prion particles from nervous tissue has been a theoretical concern. Synthetic surfactant has no risk of prion contamination. (iv) One natural surfactant has been shown to contain platelet activating factor (PAF). Synthetic surfactants can be made with greater chemical purity. c) Natural surfactants improve oxygenation faster than do synthetic surfactants. A rapid effect is not necessarily better with respect to later outcomes. d) Synthetic surfactant preparations are generally cheaper per dose than natural surfactant preparations. Synthetic surfactant treatment increases survival with less concern about adverse effects and generally lower cost per dose than natural surfactant.