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Pressure Sensor Air Accumulation Detection

IP.com Disclosure Number: IPCOM000089036D
Original Publication Date: 1977-Sep-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 3 page(s) / 47K

Publishing Venue

IBM

Related People

Mulzet, AP: AUTHOR

Abstract

Sterile, disposable processing sets are used to carry blood in vivo in a continuous flow from a donor to a processing bag contained in a rotating centrifuge. The blood is separated into components in the centrifuge, and some of the components are returned to the donor, again using the same processing set. Both the donor line and the recipient line have filters to screen out the blood clots in the flowing blood. The filters are normally housed in large diameter, thin wall, transparent plastic chambers. These chambers are designed to entrap any air bubbles carried in the blood flow.

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Pressure Sensor Air Accumulation Detection

Sterile, disposable processing sets are used to carry blood in vivo in a continuous flow from a donor to a processing bag contained in a rotating centrifuge. The blood is separated into components in the centrifuge, and some of the components are returned to the donor, again using the same processing set. Both the donor line and the recipient line have filters to screen out the blood clots in the flowing blood. The filters are normally housed in large diameter, thin wall, transparent plastic chambers. These chambers are designed to entrap any air bubbles carried in the blood flow.

In order to ensure a safe and reliable procedure, it is necessary to detect 1. when a certain amount of air has accumulated in the filter chamber, 2. when the pressure in the donor line drops below a predetermined value, and 3. when the pressure in the recipient line exceeds a predetermined value.

Each of these detections must be done without compromising the sterility of the procedure, without impacting the cost of the processing set, and without operator inconvenience.

In the present arrangement, both the air accumulation and the pressures are sensed at the air accumulation chambers. A channel structure 1 is provided which contains sensors to do the detection, and suitably designed, disposable air accumulation chambers 3 and 5 are simply pushed into the channel by the operator. All the sensing is then done completely automatically.

Air accumulation detection is done by the use of ultrasonic transducers. Identical, low cost ultrasonic transducers 7, 9, 11, 13 are built into opposite sides of the channels, facing each other. One of each pair is driven at 5 volts by an oscillator at the transducer's resonant frequency. The transducers facing the driven transducers sense the transmitted signal. The level of the signal received will exceed a first voltage if there is blood in the chamber, but will drop below a second voltage if the chamber is empty. A fixed threshold intermediate the first and second voltages is established and, if the output of the transducer drops below this threshold, the system stops the flow of blood and signals the operator. The operator must then use the air release in order to allow the chamber to refill with blood so that the system...