QUANTIFICATION OF EXTRACORPOREAL WHITE CELL AND PLATELET DEPOSITION IN CARDIOPULMONARY BYPASS - COMPARISON OF MEMBRANE AND BUBBLE OXYGENATORS

Cardiopulmonary bypass is known to activate both white cells and plate lets. The aim of this study was to investigate whether the use of bubb le and membrane oxygenators results in different degrees of deposition in the filter and oxygenator of the bypass circuit. Dual-isotope imag ing techniques were employed, with white cells labelled with Tc-99(m) and platelets with In-111, and with subsequent imaging of the filters and oxygenators on a gamma camera fitted with a medium-energy, paralle l-hole collimator, relative to a known standard. The percentage white cell oxygenator deposition ranged from 0.011 to 4.91% in the bubble gr oup (n = 20) and was not different from the membrane group (0.001 to 4 .22%). Similarly, no difference in platelet deposition was found, with 0.605-45.17% deposited in the bubble oxygenators and 0.001-15.26% dep osited in the membrane oxygenators. Filter deposition of both types of cell was substantially lower in both membrane and bubble groups with no difference between groups. The striking feature of the data is the non-normal distribution of the deposition in both types of oxygenator. This study demonstrated that both white cell and platelet deposition in the cardiopulmonary bypass circuit can be quantified using radiolab elled cells. No differences in oxygenator or filter deposition were fo und in patients randomly allocated to membrane or bubble oxygenation.