Respiratory distress syndrome (RDS) is a significant cause of illness in preterm infants. RDS is caused by a deficiency or a dysfunction of the chemicals that line the lung, called pulmonary surfactant. Numerous preparations that contain surfactants of either animal origin or synthetic design have been developed and tested to treat or prevent RDS. In general, these surfactant preparations have decreased lung rupture (pneumothorax), decreased the risk of dying, and increased the number of survivors without lung damage. From previous research, the surfactants that are obtained from animal lungs seem to have a better effect than the synthetic surfactants. This might be due to the surfactant proteins contained in animal surfactant that are absent in the previously available synthetic surfactants.
Recently developed synthetic surfactant preparations include whole surfactant proteins or parts of the proteins (called peptides) that act like naturally occurring surfactant protein. These preparations have been recently tested in comparison to the protein free synthetic surfactant preparations.
A recent trial of protein containing synthetic surfactant compared to protein free synthetic surfactant suggests that these protein containing synthetic surfactants help prevent respiratory distress syndrome and may or may not lead to a decrease in lung injury (chronic lung disease). Other clinical outcomes were similar. Further studies will help refine recommendations concerning use of protein containing synthetic surfactants.
In the one trial comparing protein containing synthetic surfactants compared to protein free synthetic surfactant for the prevention of RDS, no statistically different clinical differences in death and chronic lung disease were noted. Clinical outcomes between the two groups were generally similar although the group receiving protein containing synthetic surfactants did have decreased incidence of respiratory distress syndrome. Further well designed studies comparing protein containing synthetic surfactant to the more widely used animal derived surfactant extracts are indicated.
Respiratory distress syndrome (RDS) is a significant cause of morbidity and mortality in preterm infants. RDS is caused by a deficiency, dysfunction, or inactivation of pulmonary surfactant. Numerous surfactants of either animal extract or synthetic design have been shown to improve outcomes. New surfactant preparations that include peptides or whole proteins that mimic endogenous surfactant protein have recently been developed and tested.
To assess the effect of administration of synthetic surfactant containing surfactant protein mimics compared to protein free synthetic surfactant on the risk of mortality, chronic lung disease, and other morbidities associated with prematurity in preterm infants at risk for or having RDS.
Standard search methods of the Cochrane Neonatal Review Group were used. The search included MEDLINE (1966 - March 2009) and the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library) in all languages.
Randomized and quasi-randomized controlled clinical trials were considered for this review. Studies that enrolled preterm infants or low birth weight infants at risk for or having RDS who were treated with either a synthetic surfactant containing surfactant protein mimics or a protein free synthetic surfactant were included for this review. Studies of treatment or prevention of respiratory distress syndrome were included.
Data regarding mortality, chronic lung disease and multiple secondary outcome measures were abstracted by the review authors. Statistical analysis was performed using Review Manager software. Categorical data were analyzed using relative risk, risk difference, and number needed to treat. 95% confidence intervals reported. A fixed effects model was used for the meta-analysis. Heterogeneity was assessed using the I2 statistic.
One study was identified that compared protein containing synthetic surfactants (PCSS) to protein free synthetic surfactants. Infants who received protein containing synthetic surfactant compared to protein free synthetic surfactant did not demonstrate significantly different risks of prespecified primary outcomes: mortality at 36 weeks postmenstrual age (PMA) [RR 0.89 (95% CI 0.71, 1.11)], chronic lung disease at 36 weeks PMA [RR 0.89 (95% CI 0.78, 1.03)], or the combined outcome of mortality or chronic lung disease at 36 weeks PMA [RR 0.88 (95% CI 0.77, 1.01)]. Among the secondary outcomes, a decrease in the incidence of respiratory distress syndrome at 24 hours of age was demonstrated in the group that received PCSS [RR 0.83 (95% CI 0.72, 0.95).