ECMO Ethics: The Cardiologist's Conundrum

Extracorporeal membrane oxygenation (ECMO), is a relatively novel form of bypass treatment, primarily seen in Cardiac Intensive Care Units (CICU) for post-operative patients or the like.  Unfortunately, there are some severe side-effects that are associated with ECMO, which intrinsically sow ethical dilemmas into the already delicate fabric of treatment and care of CICU patients.  

Here's an example of the physiological breakdown of ECMO:  A baby is born prematurely.  As a result, their diaphragm did not have enough time to fully develop in time to breathe on their own.  Left untreated, this will lead to system failure, by lack of oxygen perfusion in the body, suffocating the newborn.  So what are the treatment options?  Most likely, some sort of synthetic diaphragm will be surgically placed on the newborn, and they'll grow up and be healthy.  Great!  Not so much.  Baby still needs to perfuse their little body with oxygen during the surgery and during recovery.   

Blood is drawn from a main vein the baby, typically the internal jugular vein.  The blood is fed through a tube into a rotating drum.  The RPM's on the drum create a negative pressure, sucking the blood out of the jugular.  In the drum, there are hundreds of specialized tubes that will act as artificial alveoli.  The blood is oxygenated in the drum and returned through another tube leading to a main artery, typically the common carotid artery.  

So what's the big problem?  Well, it seems that in many cases, being put on ECMO causes hemolysis, or bursting of the red blood cells (RBC).  The RBC's contain hemoglobin, the protein structure that carries the oxygen.  It turns out that hemoglobin circulating, free from the RBC is toxic in the body (Plasma-Free Hemoglobin), and causes a myriad of issues, especially in the kidney.  This leads to having to place patients on forms of dialysis, or more severely, mortality (Kim et al., 2018).  

If you’re the cardiologist, what do you do?  If you place the child on ECMO, there is a solid probability they’ll develop kidney failure, be placed on dialysis, and may die.  If you don’t do anything, they’ll die. 

What ought to be done?  No ECMO = Certain Death, ECMO = Possibility of Survival.  Previous literature has stated that the RPM values or the degree of negative pressure are what is causing the hemolysis.  Unfortunately, that does not seem to be the whole story.  A research team at Children’s Hospital Colorado is currently looking at these causes, and so far, it appears that the issues are much more complicated, and more research needs to be done.

References
Kim, JS, Hyslop, R, Powers, PE, Stanfield, N, Deakyne, S, Ellis, CW, Gist, KM. (In-Press/2018).  Evaluating the outcomes and risk factors related to hemolysis during extracorporeal membrane oxygenation (ECMO) support with a centrifugal pump. Journal of the American College of Cardiology.