Influence of different oxygenator types on changing frequency, infection incidence, and mortality in ARDS patients on veno-venous ECMO

PURPOSE: Veno-venous extracorporeal membrane oxygenation (vv-ECMO) is pivotal in the treatment of patients suffering from acute respiratory distress syndrome (ARDS). Comparative data with different oxygenator models have not yet been reported. The aim of this retrospective investigation was therefore to assess whether different oxygenator types might influence changing frequency, infection incidence, and mortality in patients on vv-ECMO.

METHODS: 42 patients undergoing vv-ECMO between 1998 and 2009 were identified. In 20 out of these patients, a polypropylene (PP) microporous hollow fiber membrane oxygenator, and in 22 patients a nonmicroporous polymethylpentene (PMP) diffusion membrane oxygenator was used. Infection incidence, changing frequency, and mortality were documented.

RESULTS: In the PMP group, an oxygenator change was necessary less often than in the PP group (p<0.001). The incidence of bacterial, viral, or fungal growth was similar in the groups, thus independent of the frequency of oxygenator change. Irrespective of the groups, the occurrence of Candida sp. tended to correlate with death (p = 0.06). In general, there was a trend towards a higher infection incidence in the subgroup with pulmonary ARDS (p = 0.07). Moreover, infection incidence was associated with a longer ICU stay (p = 0.03) and longer ECMO therapy (p = 0.03). ICU mortality was lower in the PMP group than in the PP group, although not statistically significant (p = 0.10).

CONCLUSIONS: The PMP oxygenator membranes showed benefits with regards to changing frequency, but not infection incidence, length of ICU stay, and length of ECMO therapy. There was a trend towards a lower ICU mortality in patients with PMP oxygenators.