CARDIOPULMONARY BYPASS APPARATUS

Typical Number in Hospital: 2

Cost Bands: 5,6

References: 4

This is the heart/lung machine which can take over the function of the heart and lungs for short periods to allow surgery to the heart itself, such as replacement of coronary artery, repair or replacement of defective heart valves, and the closing and correcting of atrial and ventricular septal defects.

The machine consists of a number of pumps, an oxygenator, a heat exchanger to control blood temperature, filters and a bubble trap. The procedure of cardiopulmonary bypass consists of inserting cannulae into the vena cava or the right atrium to take blood to the machine. The blood then flows into an oxygenator which also removes carbon dioxide and a pump then returns blood through a filter and bubble trap into a cannula connected to the aortic arch or to the femoral artery.

Clamps are placed on the aorta to isolate the heart and lungs. The heart usually arrests spontaneously. A small cannula is also required in the apex of the heart to drain blood returned from the bronchial arteries. The heat exchanger reduces the body temperature to approximately 28[d]C during the operation but the blood is rewarmed towards the end. Afterwards the heart may restart spontaneously or electrical defibrillation may be required.

The pumps are usually roller pumps and the oxygenator may be a bubble type or a membrane type. Further details may be found under the specific entries.

Such devices may be found in the cardiac surgery department and they are normally prepared and operated by specialized technicians (perfusionists) in conjunction with the anaesthetist.