In this study, the hypothesis was tested that a low-resistant, high-compliant
oxygenator provides better pulse conductance and less
hemolysis than a high-resistant, low-compliant
oxygenator during pulsatile
cardiopulmonary bypass. Forty adults undergoing
coronary artery bypass surgery were randomly divided into two groups using either an
oxygenator with a relatively low hydraulic resistance (Quadrox BE-HMO 2000, Maquet Cardiopulmonary AG, Hirrlingen, Germany) or with a relatively high hydraulic resistance (Capiox SX18, Terumo Cardiovascular Systems, Tokyo, Japan). The phase shift between the flow signals measured at the inlet and outlet of the
oxygenator was used to assess compliance. Pulse conductance in terms of pressure attenuation was calculated by dividing the outlet pulse pressure of the
oxygenator by the inlet pulse pressure. A normalized index was used to assess
hemolysis. The phase shifts in time of the flow pulses were 36 +/- 6 ms in the low-resistant (high-compliant)
oxygenator, and 14 +/- 2 ms in the high-resistant (low-compliant)
oxygenator group (P < 0.001). The low-resistant, high-compliant
oxygenator provided 27% better pulse conductance compared with the high-resistant, low-compliant
oxygenator (0.84 +/- 0.02 and 0.66 +/- 0.01, respectively, P < 0.001). Inlet pulse pressures were significantly higher (29%) in the high-resistant, low-compliant (Capiox) group than in the low-resistant, high-compliant (Quadrox) group (838 +/- 38 mm Hg and 648 +/- 25 mm Hg respectively, P < 0.001), but no significant difference in
hemolysis was found. A low-resistant, high-compliant
oxygenator provides better pulse conduction than a high-resistant, low-compliant
oxygenator. However, the study data could not confirm the association of high pressures with increased
hemolysis.