Good day, so I was curious about this after watching a heart transplant surgery. Normally speaking, the cardiovascular system can be considered as a closed loop system where fluids that leak out don’t introduce air bubbles into the blood stream. However, when transplanting an organ, say a heart, from a donor to a recipient, there are multiple instances where there might be a risk of introducing air bubbles to the blood stream either when being connected to an artificial blood pump or sewing the new organ in.
My question is, how is it that they manage to remove air bubbles from a patients blood stream after completing a heart transplant?
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The patients are placed on cardiopulmonary bypass, which is essentially disconnecting the vasculature from the heart and lungs and connecting it up to a machine that oxygenates blood and returns it to the body while we work on the heart. The introduction of air bubbles can happen either during connection to or disconnection from the CPB system, but we minimize that essentially by filling the tubing with saline so there’s as little air as possible in the circuit and the bypass machine itself has several filters that are supposed to minimize air bubbles. There is also constant communication between the surgeons and the perfusionist, which ensures that the blood flow is occurring correctly and in the right direction, the heart is not beating when it’s not supposed to be, etc. But there is always a small amount of air that enters the system and it can cause inflammation and intravascular thrombosis. < 20 mL of air is usually considered to be minimally harmful, and the risks of these air emboli are considered to be less than the benefit of the transplant/CABG/etc., which is why we proceed with these cases.
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