Fig. 1.

Flow chart of the review. The studies excluded from the systematic review were two full text duplicates [24, 25] reporting the same data with major methodological flaws (lack of randomization, unclear analysis, lack of allocation concealment and blinding, unclear sample size calculation, unclear outcome definition and incomplete outcome analysis/reporting) and one abstract which did not respect the eligibility criteria [22]. Two studies [42, 43] included in the systematic review were excluded from the meta-analysis because they investigated the use of non-internationally available porcine surfactants