AIR EMBOLUS DETECTOR

Typical Number in Hospital:

Cost Bands:

References: 9

Whenever fluids are infused into the blood stream it is important to prevent the passage of air into the body. Air bubbles are undesirable and a large quantity of air reaching the heart can interfere with its pumping action.

All devices which could cause air to pass into the body should employ warning and fail-safe circuits to prevent this happening. The problem is most important in the use of infusion pumps where a disconnection or exhaustion of the fluid reservoir could lead to the pumping of air. Also when blood is removed from the body for oxygenation or dialysis it is essential that blood is returned to the body free from air bubbles.

There are two main types of air embolus detector which may be separate devices or incorporated into the parent instrument. These employ optical transmission, providing a warning when there is a sudden change in transmission. Alternatively, an ultrasonic device may be employed and this may also be monitoring the flow velocity within the tube if it is carrying blood. Doppler ultrasonic flow-meters calculate the blood velocity from the back-scattered ultrasound from the blood corpuscles. Air bubbles produce echoes which are several orders of magnitude greater in intensity than is received from the blood. The appearance of these very large echoes is used to identify the presence of air in the tube. Very small bubbles can be detected by this method.