The Evolution of Cardiac ECMO at One Hospital by Gary Grist RN CCP Retired- August 2012

 

Open heart surgery using cardiopulmonary bypass (CPB) began in 1953. It was used to repair congenital heart defects, mostly in children, because patients with congenital heart disease rarely lived into adulthood. In the 1960’s that changed when coronary artery bypass graft (CABG) surgery was invented to treat acquired heart disease in adults. Researchers and manufacturers focused their attention on adult devices, supplies and techniques. There were 10 times more surgeries in adults than children, so that’s where the market focused. Pediatric cardiac surgery took a back seat, having to use modified adult devices and techniques.

The open heart program at my old hospital is one of the oldest, continuously operating pediatric programs in the country. Several pediatric surgeons did some cardiac surgery in the 1950’s and early 60’s. It was all pro bono work back then. In 1961, the first formally qualified pediatric cardiac surgeon began a regular schedule of open heart surgeries. He was soon joined by a second surgeon and for more than two decades they performed most of the pediatric cardiac surgery in the city. Both these surgeons trained with the world renowned Dr. Robert Gross in Boston and also did a Fellowship at Great Ormond Street Hospital in England. Another Boston trained surgeon came in the early 1990s when the first surgeon retired.

As late as the early 1980’s, even routine pediatric heart surgery was still very risky. Depending on the procedure, one of the first things that a surgeon would do at the beginning of heart surgery was to place a peritoneal dialysis catheter, knowing that the child most likely would go into renal failure after surgery. And, if the child failed to wean from CPB, that was the finale! There were no second chances. Several of the anesthesiologists and nurses at the hospital would baptize the infants on their foreheads as a final act of compassion during the last attempt to wean them from CPB, knowing that the child wasn’t going to survive. One of the anesthesiologists always carried a small bottle of Holy water in his shirt pocket whenever he did a heart case for just this purpose.

In the late 1980s, researchers and manufacturers finally focused their attention on pediatric heart surgery. Many new products and techniques were developed; pediatric membrane oxygenators and biocompatible circuits were less damaging to the blood and less disruptive of the infant’s physiology. Ultrafiltrators were used to control edema during CPB and to perform modified ultrafiltration after CPB to reduce bleeding and treat pulmonary hypertension. Point of care testing for ionized calcium (by itself a major advance) greatly reduced the mortality of complex surgeries like Fontan completions and aortic switch operations.

During this late 1980’s time frame neonatal ECMO for respiratory diseases came into common use as well. Being a type of heart/lung pump, the ECMO pump had the potential to support patients with failing hearts. However, the general consensus nationally among pediatric heart surgeons was that ECMO was contraindicated in most post-cardiotomy cases. The technical difficulties of supporting a post-cardiotomy patient on ECMO were too daunting; massive bleeding from the sternotomy, the need to reverse multiple organ failure, the need for very high blood flow (twice as high as for respiratory patients), the frequent development of intracranial hemorrhages and brain infarctions, and the need to keep the heart decompressed to allow it to heal. In addition, even if the patient could be successfully supported on ECMO, there was no real proof that the heart would heal. The most successful post-cardiotomy ECMO cases were patients who had simple pulmonary hypertension rather than cardiac dysfunction.

In the ten years between 1987 (when the hospital’s neonatal ECMO program started) and 1996, 18 cardiac patients were put on ECMO (less than 2 per year), about half of those being operative ‘failure to wean from CPB’ patients or ‘failure to resuscitate’ in the immediate post-op period. The rest were non-operative patients. These were specially selected patients, thought to have the best chance of survival on ECMO (none were univentricular patients). The overall survival rate for operative and non-operative cardiac ECMO patients was a respectable 33%. However, surgeons still generally felt that post-cardiotomy ECMO for most patients was an ineffective and futile effort that only prolonged the inevitable fatal outcome.

The ECMO team dreaded the use of ECMO in the post-cardiotomy patient because of all the complications. The exposure to multiple extracorporeal circuits (the cardiopulmonary bypass circuit immediately followed by the ECMO circuit and frequent ECMO circuit changes subsequently) often resulted in the manifestation of severe systemic inflammatory response syndrome; hemodynamic instability, fever, pulmonary congestion, renal failure, edema and excessive chest tube drainage. It was difficult to maintain the high blood flow needed to perfuse the organs without excessive fluid resuscitation that led to severe edema while, at the same time, keeping the myocardium decompressed.

Renal failure was such a common problem that a hemoconcentrator was frequently placed in the ECMO circuit for, at the very least, excess fluid removal or, at worst, hemodialysis. Bleeding was often so profuse that ECMO nurses had a hard time physically just keeping up with the blood loss. Patients would be exposed to scores of blood donors through multiple RBC, FFP, platelet and cryoprecipitate transfusions. On several occasions I brought our intra-operative blood salvage machine to the bedside in the ICU where it was attached to the ECMO patient’s chest tubes. It would rapidly process the shed blood and pump it back into the ECMO pump in a continuous cycle of bleeding, processing and reinfusion. Because of the need to control bleeding, heparin infusion was minimized resulting in clotting and frequent circuit change out. DIC and coagulation factor consumption was common. Glucose levels were difficult to control with the infusion of so many blood products. So, opportunistic infections propagated by high serum glucose levels were frequent. When chest cannulation was used, the cannulae were difficult to secure and, on more than one occasion, fell out during ECMO. These, and many other complications, were the normal state of affairs in post-operative cardiac ECMO patients.

Then in 1997 Dr. Gary Cooper joined the hospital. Unlike the prior heart surgeons who were very good doctors but who had other non-cardiac surgical duties, Gary’s only job was heart surgery. To support him, Gary insisted on having a full time, well trained and well-seasoned cardiac team of first assistants, OR nurses, advanced practice nurses, anesthesiologists and perfusionists. He included the ECMO team as well. Even as late as 1997, nobody really knew how to effectively use ECMO for post-cardiotomy support, not just at this hospital but in the entire nation-wide ECMO community. Even so, Gary’s attitude was that the best way to learn how to do something that nobody else knew how to do was just to do it, problem solving along the way! Waiting for other ECMO programs to solve the many problems of cardiac ECMO was not an option for him. It has been said that the difference between success and failure is primarily one of attitude. Gary’s attitude towards cardiac ECMO was not that it was a futile effort, but rather a second chance at survival for these patients. He instructed me to always have an ECMO pump available in the CV Surgery OR. And for most children (not just a selected few) who failed to wean from CPB, he would use the ECMO pump to support them until they recovered, died from a complication or the medical futility became undeniably self-evident. The ECMO program has adapted to the increased number of cardiac patients and these patients are still a great challenge. But, we are much more capable than we were prior to 1997. Many of the problems associated with cardiac patients have either been solved or we have found a way around them. Prior to 1997, keeping a cardiac patient alive on ECMO with good organ function for 7 days seemed to be the maximum limit of our abilities; the longest ECMO time for a survivor being only 145 hours. But since 1997, it isn’t unusual for a patient to be on ECMO for more than 2 weeks and still survive; the longest time for one of our survivors being 481 hours (20 days).

In the 15 years since Gary Cooper has been here (1997-2012) there have been 156 cardiac ECMO patients (about 10/yr) with a survival rate of 41%. Many of them were fail to wean from CPB or fail to resuscitate patients (including univentricular patients) who were placed on ECMO in the OR or ICU. And, most importantly, I am not aware that there has been the need for any more compassionate baptisms during CV Surgery.

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Perfusion Theory is an educational platform for the Oxygen Pressure Field Theory (OPFT). August Krogh’s theoretical concept of the oxygen pressure field is explained and then applied to clinical applications in perfusion practice.