Cardio-Pulmonary Bypass (CPB)
Cardio-Pulmonary Bypass is used during cardiac surgery, when the patient’s heart has to be stopped. Using CPB, the perfusionist is responsible for the flow of blood to the brain and to other organs while the patient’s heart is stopped. Because the lungs also cease to function, the perfusionist is also responsible for the oxygenation of the patient’s blood and removal of carbon dioxide. Cardio-Pulmonary Bypass is often abbreviated to CPB, and is also known by other names – perfusion, extra-corporeal support, and extra-corporeal membrane oxygenation. This is often abbreviated to ECMO (see below) and used for longer term support, mostly in the intensive care unit.
Intra-aortic Balloon Counter-Pulsation
The Intra-aortic balloon pump is necessary when the heart begins to fail. It is a mechanical device that increases the amount of oxygen going to the heart, while at the same time increasing the amount of blood the heart is able to circulate around the body. Increasing cardiac output increases the flow of blood to the heart itself and so circulation is further improved. When utilised in the cardiac operating room, the pump is generally managed by the perfusionist.
Mechanical Circulatory Support (using a Ventricular Assist Device)
Mechanical circulatory support utilising a Ventricular Assist Device (VAD) is designed to provide short-term or long-term support for patients whose hearts are too damaged or diseased to provide enough blood flow to the brain and other vital organs of the body. A VAD, is a mechanical pump that helps the heart to pump blood throughout the body. The pumping system and controllers are very complex and the perfusionist will be one of the team members responsible for the safe initiation and ongoing oversight of the VAD.
Blood Salvaging and Auto Transfusion
Blood Salvage or autotransfusion is a blood conservation technique involving the collection of blood from a patient’s active bleeding site and reinfusion of that blood into the same patient for the maintenance of blood volume. This is vital in minimising blood loss in the surgical setting and in limiting the need to use blood bank products on a patient. Perfusionists are key providers of this procedure in hospitals. It is not uncommon to find a perfusionist performing autotransfusion during a hip replacement or during spinal surgery.
Extracorporeal Life Support (ECLS)
Extracorporeal Life Support is most commonly known as Extra-Corporeal Membrane Oxygenation (ECMO). ECMO is a technique which provides prolonged heart (cardiac) and lung (respiratory) support to patients whose heart and lungs are unable to provide oxygenation or blood flow to sustain life. The technology for ECMO is largely derived from CPB, which provides shorter-term support relative to ECLS / ECMO. The perfusionist works with the cardiac and intensive care teams when a patient requires ECMO. The perfusionist is responsible for the circuit setup, overall maintenance and monitoring of the patient’s extra-corporeal circuit on EMCO and works closely with nurses and doctors in monitoring of the patient – maintenance and monitoring of the patient on EMCO.
Organ Procurement During Transplantation
A perfusionist is often needed in the procurement and preservation phases of heart or heart/lung transplantation. This is in addition to the perfusionist’s involvement in the cardiac surgery of the transplant itself – which, of course, involves CPB (see above).
Research & Development
Perfusionists conduct clinical and experimental research associated with all of the above procedures. They work with other clinicians, researchers, universities and industry to develop and test new devices and techniques. This work is key to patient safety and the progress of cardiac surgery as a therapeutic modality
Isolated Limb Perfusion
Limb perfusion is not very common. It is a procedure utilising perfusion techniques to deliver anticancer drugs directly to a limb – either an arm or leg. The usual flow of blood to and from the limb is bypassed using a tourniquet, and the perfusionist along with other clinicians, takes over and supports the flow of blood to the limb. The technique requires an oxygenation system and other similar aspects of whole-body CPB. Anticancer drugs are perfused directly into the limb. This allows the person to receive a high dose of drugs in the area where the cancer occurred.