A New Miniature Fiber Oxygenator for Small Animal Cardiopulmonary Bypass

There is increasing concern about brain damage as an aftereffect of cardiac surgery, especially in the aging patient population1. The severity of this damage varies from frank stroke to minor neurological deficit or neurocognitive decline. Investigation into the mechanisms of damage cannot be conducted in patients, but only in animals. Potentially neuroprotective strategies must also be tested and well tolerated in appropriate animal models. A suspected cause of damage is the use of cardiopulmonary bypass (CPB), and many attempts have been made to develop a suitable animal CPB model2. A small animal model, for example the rat rather than the dog or pig, has the advantages of cost reduction and the fact that rat behavior is well characterized. A relevant rat CPB model has recently been reported3. To mimic the clinical situation, a suitably scaled and disposable oxygenator must be used. Commercial models are expensive and grossly oversized, typically requiring two extra donor animals solely to prime the circuit. They are extremely difficult to clean (for reuse), which is crucial as it is becoming clear that immune system activation solely by the CPB circuit is less than previously assumed4. Reuse of oxygenators for experimental CPB might result in considerable immune activation by protein residues. We decided to develop an appropriately sized reusable fiber oxygenator for CPB in small animals.