eli5: Why do Heart-Lungs bypass machine can’t keep someone alive for more than days?


eli5: Why do Heart-Lungs bypass machine can’t keep someone alive for more than days?

In: 155

Being on a heart-lung bypass machine is very invasive and stressful on the body. Lots of things can go wrong, and the longer on are on it the greater the risk of severe injury or death

The main risks associated with it are bleeding out in part due to being on blood thinners.

Blood clots which can lead to strokes and death

Air embolism meaning that air bubbles get into your bloodstream

Inflammation throughout your body

Brain injury, lung injury, Kidney injury or kidney failure, Multi-organ failure, and Pancreatitis due to lower heart and lung function, blood clots, and inflammation.

Ideally a person should only be on such a machine for a few hours during surgery, but sometimes longer is required due to waiting on organs for transplant etc. But the longer you are on the machine the lower your chances of survival.

While standard ECMO is 5 days, they have gone as long as 25-30 days.
The big issue is that the heparin they use to prevent clotting can also cause brain bleeds, etc.

Blood clots outside of the body, so we have to use very powerful anti-clotting meds (heparin). Besides the obvious bleeding issues, it causes side effects in long term use. But the main thing you worry about is a massive brain bleed or bleeding in another part of the body because of the heparin.

Exposure to all of the foreign surfaces from the heart lung machine also chews up the clotting factors the longer you are on bypass.

As others mentioned, patients can be on ECMO for months, but it’s an incredibly invasive procedure. Blood clots can form and clog up the machine causing catastrophic failure, they can form in the brain and other organs which is why they’re on heparin which can cause the opposite problem. If the cannulas become dislodged you can bisect arteries and veins. Had one patient they were trying to place on ECMO, the aorta was bisected in the process and they bled out in minutes

Anytime you introduce something foreign to the body you are risking infection. Secondary infections/pneumonias are common and cause more damage to the already weak and damaged body

Have had patients, particularly COVID patients where the machine simply couldn’t compensate enough for the failing lunge/heart and organ transplants take a long time to get. Organs enduring low oxygenation/blood pressures for weeks leading to organ failure and brain injuries

To save the body you put it through extremes that can fuck it up in new ways. Frankly saving a life at any cost is not always worth it