Blockage hazard alarm in an intravenous system

• US 4,762,518 A
• Filed: 08/01/1986
• Issued: 08/09/1988
• Est. Priority Date: 08/01/1986
• Status: Expired due to Term

• Current Assignee: Hospira Incorporated (Pfizer Inc.)
• Original Assignee: Pancretec, Inc. (Abbott Laboratories)
• Inventors: Kreinick, Stephen J.
• Primary Examiner(s): Pellegrino, Stephen C.
• Assistant Examiner(s): Lewis, Ralph
• Application Number:
  US06/892,318
• Time in Patent Office: 739 Days
• Field of Search: 250/571, 250/577, 356/135, 128/DIG. 13, 604/122, 604/31, 604/245, 604/65
• US Class Current: 604/245
• CPC Class Codes: A61M 2205/3306 Optical measuring means
• CPC Class Codes: A61M 5/16854 by monitoring line pressure
• CPC Class Codes: G01N 21/552 Attenuated total reflection

Abstract

The principal of total internal reflection is utilized in sounding an alarm in a medical fluid infusion system when a downstream blockage occurs. A miniature prism is mounted in a cavity in a rigid exterior tube. The infusing fluid flows in a plastic tubing along the central channel of the rigid tube. The plastic tubing in the interior of this exterior rigid tube is diametrically expansive with an unpressurized outside diameter which is less than the inside diameter of said rigid exterior tube. A light source and light detector is positioned adjacent to the equilateral planes of the prism mounted in the rigid tube. When an overpressure caused by a downstream blockage in the infusion system occurs, the inner expansive tubing distends diametrically and contacts the hypotenuse plane of the prism causing the light incident on the hypotenuse plane to change from the reflective mode to the refractive mode which interrupts the signal received by the light detector which is located adjacent to one of the equilateral planes of the prism which would project the light ray out of the prism when the system operates in the reflective mode.

Claims

1. A medical infusion blockage alarm system comprising an external flexible conduit tubing,

a rigid tubing,

a central channel,

connecting means,

and internal expansive plastic tubing with an index of refraction close to that of water,

an optical prism of a high index of refraction,

a light source,

a light detector,

alarm means said external flexible conduit being connected to said rigid tubing forming interiorly and concentrically said central channel and in said central channel, a length of said internal expansive plastic tubing containing a flowing liquid and attached by said connecting means to the interior of said rigid tubing and said expansive plastic tubing having an outside diameter which is less than the inside diameter of said rigid tubing so that an air space exists between the exterior of said expansive plastic tubing when it is not in an expanded state, said rigid tubing having a cavity created in its wall to hold said optical prism, said optical prism having two equilateral planes and one hypotenuse plane,

where said hypotenuse plane is adjacent but not in contact with said internal expansive plastic tubing through which said liquid flows in said central channel and

said light source interfacing one of said equilateral planes and said light detector interfacing with other said equilateral plane with said alarm means connected to said light detector and said light source so that light rays emitted from said source enters said first equilateral plane, illuminates said hypotenuse plane and is reflected from said hypotenuse plane to penetrate other said equilateral plane to illuminate said light detector, but if said internal expansive plastic tubing is diametrically enlarged because of some excessive internal pressure of said liquid in said central channel, a wall of said internal expansive plastic tubing contacts said hypotenuse plane causing the light of said source to refract out of said illuminated hypotenuse plane, interrupting the illumination of said light detector thereby terminating a signal to cause said alarm means to sound.