A comparison of two oxygen transfer strategies: Bentley Univox and the Bard HF 5000

The purpose of this study was to evaluate the oxygen transfer performance of two membrane oxygenators: Bentley Univox and the Bard HF 5000. This evaluation was based on the comparison between: (1) the oxygen transfer slope; (2) the gas phase-arterial oxygen gradients; (3) the degree of blood shunting; (4) the maximum oxygen transfer; and (5) the diffusing capacity calculated for each membrane. The data were examined at both absolute values and relative to each device's membrane surface area. In absolute terms, the HF 5000 performed better than the Univox in each category. However, when surface area was taken into account, the Univox was clearly more efficient with regard to oxygen transfer. We conclude from this evaluation that the Univox does not offer a satisfactory oxygen transfer 'buffer' for larger, more metabolically active patients (297 ml/min for the Univox and 447 ml/min for the HF 5000). The trade-offs that were made between design and performance features, with the Univox, were unacceptable.