What Does a Perfusionist Do?

We know surgeons perform surgery. But behind every operation is a full team of specialists working in quiet coordination. In our What Do They Do? series, we spotlight some of the lesser-known, but absolutely essential, members of that team. Today, we’re taking a closer look at perfusionists.

Giving Your Heart and Lungs a Break

Your heart and lungs work together to circulate oxygen-rich blood to the rest of your body. So what happens when one or both of those organs need surgical repair? How do you keep breathing, keep living, while your heart is paused?

That’s where a perfusionist comes in.

Perfusionists operate the cardiopulmonary bypass machine, or heart-lung machine, a specialized device that temporarily takes over the function of both the heart and lungs during surgery. It draws blood out of the body, adds oxygen, removes carbon dioxide, and pumps the oxygenated blood back in—allowing the surgeon to repair the organ while the patient’s vital functions remain stable.

It’s a behind-the-scenes job that makes some of the most complex procedures possible.

Terms to Know: Perfusion refers to the passage of fluid (usually blood) through tissues or organs to deliver oxygen and nutrients.

The heart-lung machine is used during surgeries that interrupt the body’s normal blood flow, including:

Heart transplants
Lung transplants
Open-heart surgeries
Surgeries involving the aorta (the large blood vessel that carries blood from the heart to the rest of the body)

Providing Extended Support

Perfusionists also manage ECMO (extracorporeal membrane oxygenation), a form of life support used when the heart or lungs are failing. ECMO works similarly to the heart-lung machine but is used over longer periods, often as a bridge to transplant or recovery.

Managing ECMO is a delicate process. Patients can be on support for days or weeks, and perfusionists must carefully balance oxygenation, blood flow, and other metrics to keep the body functioning while the heart or lungs heal—or until a donor organ becomes available.

Performance Under Pressure

Like anesthesiologists, perfusionists are responsible for managing complex machinery and responding to the body's needs in real time. Their work demands deep expertise, calm focus, and near-constant monitoring.

In the OR, they don’t just run the machine—they monitor blood gases, temperature, electrolytes, and medications. They adjust flow rates and oxygen levels. And they do all of it while the clock ticks and the stakes stay high. There’s little room for error, and no moment to zone out.

Quietly Keeping You Alive

You may not hear about them often, but perfusionists are central to many of the most life-saving surgeries performed today. They are the quiet force in the room, running the machine that lets your heart rest so it can heal, and making sure your brain and body stay perfused every second of the way.

So if you or someone you love has ever had heart or lung surgery, chances are a perfusionist was there too, helping make the whole thing possible.