|Previous: BLOOD PRESSURE MONITOR/METER||Next: BLOOD VELOCITY METER|
|Typical Number in Hospital: 20||Cost Bands: 2,3||References: 3|
The pumping of blood is required during haemodialysis and during open heart surgery. Roller pumps, which produce a peristaltic flow of blood, are the most common. These have the advantage that the pump mechanism does not come into contact with blood. The mode of operation is for a soft tube carrying the blood to be pressed into a special groove (shoe) and two or more rollers on a rotating spindle occlude the tube in turn pushing the blood forward. The design of the shoe and the rollers must be such that the tube is always occluded at at least one point to prevent leakback.
In haemodialysis the pump may be incorporated into the machine or may be a separate device which controls the flow of blood from the body and drives it through the dialyser.
Blood damage (haemolysis) is reduced if the following precautions are taken:
1. The tubing compressed by the rollers should be relatively soft but not too soft. Very soft tubing allows considerable movement between the tube walls and the roller.
2. Use the largest diameter of tube possible.
3. If the rollers are set so that they only just occlude the tube this reduces haemolysis and tube wear.
4. Use lubricants (e.g. silicone jelly).
Content and Design Copyright 2000 Dr. Malcolm C Brown. See Title Page for more details