Surgery – Diagnostic testing – Cardiovascular
Patent
1994-11-04
1998-04-21
Rimell, Sam
Surgery
Diagnostic testing
Cardiovascular
128748, A61B 502
Patent
active
057412162
DESCRIPTION:
BRIEF SUMMARY
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a national stage of PCT/DK93/00122 filed Apr. 1, 1993, filed under 35 USC 371.
The inventions relates to pressure monitors and to be more specific to pressure monitors for measuring the pressure in a catheter.
From WO 90/07942 it is known that the overall correct function of an infusion pump may be supervised by considering the course of the pressure in the outlet catheter during each pumping cycle. It is important that the actual pressure in the very catheter is measured and not just the resistance a piston exerts against movement.
It is the object of the invention to provide a pressure monitor measuring the pressure in the catheter directly.
This is obtained by a monitor comprising a light emitting device and a light measuring device placed opposite each other leaving a space for insertion of a measuring zone of the catheter between these parts, this measuring zone lying downstream of a possible output valve of a pump, and a computer circuit transforming the signals from the light measuring part into signals representative to the pressure.
The light source may be one or more cooperating surface light emitting diodes jointly having a size corresponding to the size of the measuring zone.
Correspondingly, the photo sensitive device may be formed by one or more photo cells working in parallel and jointly having a size corresponding to the size of the light emitting device.
The measuring zone may be a part of the catheter tubing or may be an appendix to the catheter, this appendix forming a manometer tube.
When the manometer tube solution is used, the light measuring device may appropriately be a linear array of mutually independent photocells, this array having a length corresponding to the length of the branch tube. With this embodiment of the light measuring part it can be measured to which extent the infusion liquid rises in the manometer tube.
Catheters for infusion pumps may have the shape of a tubing forming the complete flow path for the liquid to be infused from a reservoir. The pumping function may be obtained by part of the catheter forming a part of a peristaltic pump or being provided with another sort of pumping unit. In the last mentioned case, the manometer tube may be provided in this pumping unit downstream of the outlet valve of this unit. Thereby it is possible to mould the pumping unit with the manometer tube to obtain a more precise manometer tube.
The invention also comprises a catheter provided with a branch tube forming a manometer tube. This branch tube may appropriately be provided near a pump delivering an infusion liquid through the catheter, but downstream in relation to the output valve function of this pump.
A catheter may comprise a pumping unit forming a part of this catheter, and the branch tune may be provided as a bore in this unit.
In the following the invention will be described with reference to the drawing, wherein
FIG. 1 schematically shows a monitor comprising a light emitting part and a light measuring part with an interjacent measuring zone of a catheter,
FIG. 2 schematically shows a monitor as shown in FIG. 1 where the measuring zone of the catheter is provided as an appendix to the catheter,
FIG. 3 schematically shows a monitor measuring the level in a manometer tube.
A pressure monitor for measuring the actual pressure in a catheter is shown schematically in FIG. 1. The monitor comprises a light source 1 which may be a light emitting diode, LED, emitting its light from an elongated surface, a photo cell 2 for receiving light on a surface of about the same size and shape as the light diode. The LED and the photo cell are placed opposite each other and spaced so far that room is made for accommodating a measuring zone of a catheter 3.
It has appeared that the light transmission through the liquid filled catheter varies with the internal pressure in the catheter, and consequently an output signal reflecting the pressure variations in the catheter may be obtained from the photo cell. The signal is lead to
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Hemmingsen Allan
Steffensen Bo
Novo Nordisk A S
Rimell Sam
Zelson Esq. Steve T.
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