Ultrasonics detect bubbles in IV lines
Nobody knows for sure exactly how many air bubbles in an IV line signals danger, but everyone agrees they are a very bad idea for patients
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The good news is that modular devices, which fit most types of intravenous tubing, can immediately detect these bubbles. LifeGuard air bubble detectors, for example, are small plastic units with an ultrasonic transmitter and receiver on each side of the tubing. The tube is pressed in to make contact on both sides and bubbles are detected by a disruption in the signal path.
The devices, made by Zevex, Salt Lake City, USA, incorporate all necessary electronics in the bases of the units and dry couple to PVC, silicone and many other types of tubing. They can either be supplied in three standard sizes, with channel sizes of 0.1, 0.13 or 0.2 inch (2.5, 3.3 or 5mm) for 0.125, 0.155 or 0.25 inch (3.2, 3.9 or 6.4mm) tubing. Alternatively, they can be rapid prototyped to provide channel sizes of 0.08 to 0.4 inches (2 to 10mm) for tubes from 0.1 to 0.45 inches (2.5 to 11.4mm) across. Air detection thresholds for the standard sizes are 10, 20 and 40 micro litres. Prices are around £100 per sensor.
