Air Detector with Trap

Introduction

The infusion therapy and diagnostics are more and more applied in the clinical practice. The most important and common requirement is the patient protection against the air embolism, i.e. against the thrombosis of human vital blood vessels by air bubbles contained in the infused biological fluids.

Known infusion systems with low (0.5 ml/h to 1.0 ml/s) infusion rates include special elements (burettes) that separate air bubbles from the infused fluid in the fluid delivery line. Infusion pumps, if any, include also systems of detecting the air bubbles that produce the corresponding alarms. Every manufacturer of infusion apparatuses and systems develops its own air bubble detecting and signaling devices that increase the infusion system cost.

The main disadvantage of these devices is the impossibility to use them for a higher rate infusion. The infusion with the rates 1 through 50 ml/s are necessary in such diagnostics procedures as the angiography and cardiography of the blood vessels including the brain vessels, the coronography, etc., in which the contrast fluids are infused directly into the arteries under the large pressure. The burettes and sensors used in the low-rate infusion systems are insufficient under such infusion rates.

In 1982 the author developed and patented [1] a high-rate device used in the injectors for the angiography, including those for the cardio-synchronized angiography [2], [3]. The main disadvantage of this device is that it automatically and momentarily interrupts the procedure if any bubble is detected in the injection channel. After manual removing the bubble, the entire procedure must be repeated from the very beginning. Such repetition is highly undesirable because the contrast fluids are rather toxic.

The intended device

An universal autonomous device devoted to detect and remove air bubbles in high-rate infusion systems is intended. The main advantage of the intended device is that the bubble is removed automatically, with no interruption of the procedure. The device works under any infusion rates, it is based on the combination of a mechanical air trap and optoelectronic indicator of bubbles. If there is an air bubble in the injection channel but the trap fails, then the indicator indicates the bubble and forms the command for automatic and momentary interruption of the injection.

The optoelectronic indicator is protected against a false run based on the control of the rate of the bubble movement between the two optocouplers of the indicator and comparing of this rate with the predefined injection rate. The air trap has a special chamber that enables removing air bubbles from the injection channel even if the injection rate is rather high.

The price of the intended device in the mass production can be $400 - 500.

References

1. G. Tverskoy, A. Luskin An apparatus for intervessel injection medications. USSR author's certificate No 992066, 1982
2. Prof. M. Litkin, G. Tverskoy, M. Okun. Results of experiments with a cardiosynchronized injector. "Vestnik khirurgii", Academy of Medical Sciences, No. 10, 1987, USSR.
3. G. Tverskoy Devices for the patient's protection under infusion procedures. "Trudy Granit Institute", No. 6, 1988, USSR.