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Ann Thorac Surg 1995;60:336-337
© 1995 The Society of Thoracic Surgeons
DR RALPH E. DELIUS (London, England):
Doctor Walters, I enjoyed your presentation very much. I am curious if you have taken these data and defined any indications for extracorporeal membrane oxygenation (ECMO). As you know, the indications for ECMO in cardiac patients are not as well defined as they are in respiratory patients, and in many centers, there is a tendency to keep on supporting the patients until there is really nothing left to save anymore.
DR WALTERS:
Doctor Delius, this study was a retrospective analysis, and therefore I cannot honestly say that there were strict criteria for the institution of ECMO during the 9
-year period. We have not yet developed strict criteria. When we have a patient who has severe right, left, or biventricular failure or a patient with a pulmonary hypertensive crisis who is unresponsive to medical therapy, we try to institute ECMO therapy before any major end-organ damage has occurred. It is purely an individual clinical judgment at our institution at this time.
DR THOMAS L. SPRAY (Philadelphia, PA):
That was a very nice series. You noted that some of the patients had problems with a higher creatinine level and that that was a relative predictor of nonsurvival. I wonder whether there was any evidence that those patients were placed on ECMO later in the course of their low cardiac output syndrome and that was why you happened to see a higher creatinine value at 48 hours after initiation of ECMO. The mean time to initiation of ECMO postoperatively was fairly long in your series, more than 30 hours, which suggests that these patients had gone a fairly long time after operation before most of them were put on ECMO.
My second question has to do with the neurologic problems you noted. Were the neurologic events in any way related to the side of the neck cannulation? Do you think there is any difference whether those patients are cannulated from the neck or the chest, and do you reanastomose the vessels in the neck in these patients after they are weaned from ECMO support?
DR WALTERS:
Doctor Spray, in this analysis, I did not specifically look for a correlation between longer time to the institution of ECMO and patients who had an elevated creatinine level.
The subject of future investigation at our institution is to look not only at the actuarial survival of ECMO patients but also at the long-term neurologic outcome. As you know, that is a very difficult thing to do because many of these patients have Down's syndrome and other reasons besides ECMO for neurologic abnormalities. To date, we have detected no definite correlation between neck cannulation and neurologic events.
DR J. TERRANCE DAVIS (Columbus, OH):
I enjoyed your report very much. My colleagues and I struggled also with the indications on how long to wait: when is it time to go ahead with ECMO and when is it time to try more medical therapy. One indication may be the overall percentage of time that you go to ECMO. Do you have any sense over this same 9-year period how many open heart procedures were done? Can you tell us what percentage of your patients end up getting ECMO support?
DR WALTERS:
Doctor Davis, our overall incidence of the use of ECMO in about 2,500 open procedures over 9 years is 3%, and in the last year, it was 1.4%. In the literature, the incidence ranges from 1.5% to approximately 8% at other institutions that report their frequency of ECMO usage.
DR PEDRO J. del NIDO (Pittsburgh, PA):
This is a very nice study. When we looked at our series, my colleagues and I did not find cardiopulmonary bypass time to be a risk factor. After some consideration, we thought that perhaps the reason was our hesitancy to go to ECMO or at least our relatively low threshold to go to ECMO in these children. Therefore we did not make multiple attempts to wean them from bypass before instituting ECMO.
Can you give us an insight as to what criteria you now use to decide when a child is not going to come off bypass and you are going to try to support him or her on ECMO?
DR WALTERS:
Doctor del Nido, the patients who need ECMO support in the operating room have some form of left ventricular failure or biventricular failure. When we are unable to discontinue cardiopulmonary bypass despite the administration of multiple pharmacologic agents such as dopamine hydrochloride, dobutamine hydrochloride, epinephrine, and afterload reducers, we put the patient back on bypass for a prolonged time to rest the heart, and then we try again to wean him or her. However, I emphasize that when we calculated our cardiopulmonary bypass times, for the purposes of the analysis of survivors versus nonsurvivors, we calculated the cardiopulmonary bypass time to the first time of termination. We did not include the periods during which we ``rested'' the heart on cardiopulmonary bypass.
DR del NIDO:
How did you determine whether residual defects were a reason for instituting ECMO either immediately postoperatively or in the first 24 to 48 hours?
DR WALTERS:
During the latter part of the study period, we used transesophageal echocardiography in the operating room whenever we suspected that we were going to have to institute ECMO. Our express purpose in doing this was to look for residual lesions. In patients in the intensive care unit who had had an interval of relative clinical stability, we used either transesophageal echocardiography or transthoracic echocardiography. Early in the series, though, transesophageal echocardiography was not available.
DR JOHN E. MAYER, JR (Boston, MA):
Can you tell us how many patients had a residual defect?
DR WALTERS:
None of the patients in this series had a residual defect.
DR JOHN W. BROWN (Indianapolis, IN):
That was a very nice series with good survival. Could you outline your indications for institution of ECMO in the subset placed on ECMO several hours to days after cardiac repair. All of us struggle with this subset, and there will probably be a number of institutional variations.
In our series, our group 2A patients have twice the survival of our group 2B patients, which is the opposite of what you report. At our institution, if a baby is having difficulty in the operating room and the intraoperative echocardiogram shows no additional correctable problems, we tell the perfusionist to set up an ECMO circuit, and we rest the baby for 2 or 3 days on ECMO. It is interesting that our institutions have the opposite results in the 2A and 2B groups.
Is nitric oxide used in your institution? If so, does it have any effect on the incidence of your use of ECMO postoperatively?
DR WALTERS:
Doctor Brown, we have not yet used nitric oxide on our service. I can tell you, though, that the number of patients we have lately had to put on ECMO for pulmonary artery hypertensive crises is much reduced. We seem to be treating those patients better medically now than we did in the first 5 years of the series.
Related Article
Ann. Thorac. Surg. 1995 60: 329-336.
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