PERFUSION REPORTS
Before bypass a small amount of fluid was noticed on the floor beneath the oxygenator, although this was believed to be condensation. On bypass a small amount of blood was noticed to be leaking from the oxygenator fiber block. The volume was minimal, approximately one drop every 5mins, the surgeon was informed and it was agreed to continue the case without further action unless the leak volume increased.
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The case proceeded without any intervention. Following the procedure the oxygenator was flushed and retained for analysis by the supplier.
The subsequent report from Medtronic stated the following:
'At Medtronic’s Quality Laboratory, inspection showed a blood path through the mandrel-to-heat exchanger bond. No fiber leak was observed. The leak in this case was coming from a mechanical joint and clearly not a ‘water to blood’ leak across the heat exchanger. This was a leak path to the outside of the device due to a bonding issue that has since been corrected in production, you can see from the diagram where the leak path to the outside of the device is located and from where the Affinity in question was leaking.
Medtronic has identified that mandrel-heat exchanger bond leaks are most likely related to a UV adhesive void in the bond joint. In response to these leaks, an internal corrective action was initiated and resulted in improved manufacturing process. The mandrel is actually a mechanical joint between two pieces of plastic bonded together. It is the mating joint where the heat exchanger is attached to the oxygenator bundle, last step in the assembly process. The diagram shows where the joint (i.e. mandrel) is located. The joint is designed so that it is always under positive pressure and leaks from the inside out, thereby being a fluid leak from the blood side of the oxygenator to atmosphere.'
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