BLOOD LEVEL DETECTOR

Typical Number in Hospital:

Cost Bands:

References: 3

During haemodialysis, blood passes from the patient through the artificial kidney (dialyser) and is returned to the body via a bubble trap. This is a broad chamber in which bubbles rise, thus preventing air being pumped back into the patient via the venous return tube which leaves the chamber at the bottom. As the quantity of air at the top of the trap builds up, so the blood level falls.

A blood level detector may be a photoelectric detector on the trap to show when blood has fallen below an acceptable level. The technique is not completely foolproof because of frothing, and so a second photoelectric detector on the narrow outlet tube is sometimes used. If air is detected, or the blood level falls too low, an alarm sounds and the dialysis may be interrupted until the condition is corrected. On some modern machines air may be detected in the blood by an ultrasonic detector combined with a clamp for extra safety.

The blood level detector may be an integral part of the dialysis machine, or it may be a separate device.