Ann Thorac Surg 1997;63:959
© 1997 The Society of Thoracic Surgeons
Invited Commentary
Invited Commentary
Thomas M. Egan, MD
See also page 954.
Doctor Nagahiro and his colleagues have attempted to address one of the serious shortcomings of isolated perfused lung preparations in small animals by incorporating a membrane oxygenator into the circuit to add carbon dioxide and remove oxygen so that the gas exchange characteristics of the lung block can be better assessed. They correctly point out that gas exchange is difficult to evaluate in an isolated perfused setting because of the limitations posed by the volume of the "one-pass" venous blood or the cumbersome nature of paracorporeal models. Isolated perfused preparations have other limitations, including nonpulsatile flow, the potential for venous obstruction, and the addition of a blood interface with a foreign material, which may predispose to clot formation or the activation of complement. Nevertheless, Nagahiro and colleagues demonstrated that their model was relatively stable using freshly retrieved lungs perfused for 5 hours. However, attempts to perfuse lungs with a more physiologic flow rate led to the development of pulmonary edema, a serious limitation to this and other isolated perfused preparations.
Nagahiro and colleagues chose to study the effect of the addition of EPC-K1 to conventional low-potassium dextran glucose solution after 24 hours of hypothermic storage. EPC-K1 is a derivative of L-ascorbic acid and has the potential to scavenge hydroxy radicals and to inhibit phospholipase a2, both of which may be beneficial in ameliorating reperfusion injury. lungs were perfused for only 2 hours in the experimental groups. after 2 hours of reperfusion, oxygenation was found to be better in the lung blocks that had been flushed with the perfusate with the epc-k1 added. given that the model was relatively stable up to 5 hours, continuing the experiment beyond 120 minutes might have shed more light on the merits of epc-k1. was the improvement in gas exchange really a manifestation of reduced reperfusion injury? or did the additive simply delay the onset of pulmonary edema and graft dysfunction? there is no question that severe pulmonary edema developed in the lungs stored for 18 hours without the additive, as evidenced by a very high wet--dry weight ratio at the end of the experiment. we are left to ponder what would have happened to the lungs that received the additive if the experiment had been prolonged.
This report is one of an increasing number of reports that support the addition of free radical scavengers to pulmonary preservation solutions. Clinical trials will be required to establish the utility of these additives.
Related Article
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EPC-K1 Is Effective in Lung Preservation in an Ex Vivo Rabbit Lung Perfusion Model
- Itaru Nagahiro, Motoi Aoe, Motohiro Yamashita, Hiroshi Date, Akio Andou, and Nobuyoshi Shimizu
Ann. Thorac. Surg. 1997 63: 954-959.
[Abstract]
[Full Text]
