Oxygenators are used – for example during operations – for exchanging blood gas in the extracorporeal circulation and for temperature regulation of the arterial blood. These devices are made partly of highly transparent polycarbonate. The oxygenators are rinsed and cleaned with water and alcohol after use and immediately before they are used in the operating room. At some time, complaints started to arrive from the hospitals about a product series, and they quickly increased.
The complaints related to surface cracks on an aspiration port. The risk emanating from this is firstly a mechanical weakening of the material, which is more or less obvious to see, and secondly – far less obvious – microbes accumulating in the cracks, which are protected in the crack from direct contact with the cleaning agents. In this way, they can come into contact with the blood.
Analysis with the polarisation microscope shows that the material used to manufacture the oxygenator housing is subjected to heavy stresses. This can be seen from the vivid, sharply defined colour patterns in the picture. The photo also shows contamination in the area of an aspiration port.
Through an efficiently functioning damage management system, the complaints were correlated with the effects resulting from a change of raw material supplier. Based on the results, it was found that, after changing the material, the production parameters had not been adjusted to the different material viscosity. The damage analysis thus led directly to suitable remedial measures.