Extracorporeal membrane oxygenation in infants with congenital diaphragmatic hernia: a systematic review of the evidence

AIM: The aim of this study was to evaluate the evidence supporting the use of extracorporeal membrane oxygenation (ECMO) in infants with congenital diaphragmatic hernia (CDH) and severe respiratory failure. METHODS: Medline, Embase, ISI Current Contents and Biosis databases were searched using a defined strategy. Case reports and opinion articles were excluded. We performed: 1) a systematic review of non randomised studies comparing mortality when ECMO was not available with a period when ECMO was available. Mortality was classified as "early" (before hospital discharge) and "late" (after discharge). Patients were classified as "ECMO" and "non-ECMO" candidates according to criteria reported by the authors; 2) a meta-analysis of randomised controlled trials (RCTs) comparing ECMO and conventional mechanical ventilation (CMV). Differences in mortality are reported as relative risk (RR) and 95 % confidence intervals. RESULTS: A) SYSTEMATIC REVIEW: 658 studies and 21 (2043 patients) fulfilled the entry criteria. Both early (RR 0.60 [0.51-0.70]; p < 0.001) and late mortality (RR 0.63 [0.53-0.73]; p < 0.001) were significantly lower when ECMO was available than when ECMO was unavailable. This difference in mortality was observed in "ECMO candidates" (RR 0.46 [0.32-0.68]; p < 0.001) but not in "non-ECMO candidates" (RR 0.80 [0.58-1.10]; p = 0.17). B) META-ANALYSIS: 3 trials comparing ECMO and conventional ventilation were identified which included 39 infants with CDH. The early mortality was significantly lower with ECMO compared to CMV (RR 0.73 [95 % CI 0.55-0.99]; p < 0.04), however, late mortality was similar in the two groups (RR 0.83 [0.66-1.05]; p = 0.12). CONCLUSIONS: Non randomised studies suggest a reduction in mortality with ECMO. However, differences in the indications for ECMO and improvements in other treatment modalities may contribute to this reduction. The meta-analysis of RCTs indicates a reduction in early mortality with ECMO but no long-term benefit. A large RCT in infants with CDH and severe respiratory failure is warranted.