1.1 Introduction
Cardiovascular diseases are the leading cause of death globally. Different types of cardiac operations are performed every day in hospitals varying in complexity to treat several lesions such as coronary artery bypass graft, heart valve replacement and total heart replacement. Cardiopulmonary bypass (CPB) is a crucial technique employed in the majority of these operations (Punjabi and Taylor 2013). It takes over the function of the heart and lungs during the surgery to maintain the adequate circulation of oxygen and nutrients over the procedure.
1.1.1 Coronary artery bypass graft (CABG)
CABG is a common procedure that used CPB to treat the blockage of the coronary arteries. It diverts blood …show more content…
To achieve the adequate blood volume drainage via venous cannula, it is very important to select appropriate cannula radius size. Basically, high blood pressure with a small cannula diameter leads to turbulent flow of the blood according to Reynolds number (Machin and Allsager 2006). The correct position of the cannula also plays an essential role in the blood volume drainage. Practically, the adequate venous blood volume is achieved by releasing the venous line clamp and allow the pump to receive the adequate volume that play a crucial role in the elimination of the air embolism risk. Then, the venous blood is pumped via a roller pump to the blood gas exchanger in order to purify and oxygenate the incoming blood before returning to return it back to the patient. Inside the hollow fibre membrane chambers, blood is flushed through a hollow fibre membrane in order to allow blood gas exchange and purification of the deoxygenated blood. Finally, the purified blood is returned back to the patient via the arterial cannula. The schematic diagram below shows the blood flow cycle within the heart lung machine during the operation (figure