AIR EMBOLI DETECTOR

• US 3,812,482 A
• Filed: 02/26/1973
• Issued: 05/21/1974
• Est. Priority Date: 02/26/1973
• Status: Expired due to Term

• Current Assignee: Justin S. Clark
• Original Assignee: Justin S. Clark
• Inventors: Clark, Justin S.
• Primary Examiner(s): Caldwell, John W.
• Assistant Examiner(s): Myer, Daniel
• Application Number:
  US05/336,112
• Time in Patent Office: 449 Days
• Field of Search: 340/237R,237S 250/218,573,574 356/38,39,103,207,208,40,41,42 73/194E 128/214E,214F,DIG.13
• US Class Current: 340/515
• CPC Class Codes: A61M 1/3626 Gas bubble detectors
• CPC Class Codes: Y10S 128/13 Infusion monitoring

Abstract

A light emitting diode and a photodetector are disposed on opposite ends of an optical path oriented at an angle with respect to a substantially transparent blood conduit, such as clear plastic tubing. Liquid, such as blood or saline, whether opaque or clear, flowing in the tubing defracts the light emitted by the diode out of the straight optical path so that only an insignificant portion thereof reaches the detector, but gas, such as air emboli, due to lower indexes of refraction than liquids, hardly defracts the light, so that a significant portion reaches the optical detector. An output of the optical detector in excess of a setable threshhold causes an alarm and a disablement of the blood handling system. The optical system is tested with liquid in the tubing by over-driving the light emitting diode so that, despite defraction, sufficient light should reach the detector to cause it to provide an output equivalent to the output it would normally have when detecting gas in the tubing with the light emitting diode driven in a normal manner.

Claims

1. A system for detecting gas bubbles in a liquid comprising:

an opaque block having first and second bores therethrough intersecting each other at an angle;

a substantially translucent conduit for conducting a flow of liquid in which the presence of gas bubbles is to be detected, said conduit disposed in a first one of said bores;

a light emitter and an optical detector disposed at opposite ends of a substantially straight optical path within said second bore, said optical detector providing an output signal, the magnitude of which is a function of the intensity of light delivered thereto along said optical path, such that the presence of fluid in said conduit at the intersection therewith of said light path defracts light from said optical path, whereby said optical detector has an insignificant output;

means for exciting said light emitter;

a source of a reference signal; and

means for comparing the output signal of said optical detector with the reference signal of said source and for providing an alarm signal in response to the signal output of said optical detector being of a greater magnitude than said reference signal.

2. A system according to claim 1 and further comprising means responsive to said alarm signal for registering an alarm condition.

3. A system acocording to claim 2 further comprising:

alarm signaling means responsive to said alarm registering means for signaling an alarm condition.

4. A system according to claim 2 wherein said alarm registering means comprises means setable in either of two states, said means when set in a first one of said states generating an enable signal indicative of the lack of an alarm condition, said means when set in the other of said states generating a signal indicating a registered alarm condition, said means being set in said second state by said alarm signal, and further comprising:

selectively operable means for setting said bistable means into said first state.

5. A system according to claim 4 wherein said selectively operable means comprises a manually operable switch.

6. A system according to claim 1 wherein said means for exciting said light emitter comprises means for providing normal excitation to said light emitter, and selectively operable means for providing excitation to said light emitter which is significantly greater than normal, whereby said light emitter emits light of a given intensity normally, and emits light of intensity significantly greater than normal in response to the operation of said selectively operable means.

7. A system according to claim 6 including test means presenting a test manifestation which by its presence controls the testing of said system, said test manifestation connected to said selectively operable means foR operating the same, thereby to increase the intensity of light emitted by said light emitter, and wherein said test means includes means responsive to said test manifestation in the absence of a signal from said compare circuit to generate said alarm signal and responsive to the presence of an output from said compare circuit in the absence of test manifestation to generate said alarm signal.