Patent US5242408A successfully refreshed from Google Patents.
US5242408A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for determining pressure and detecting occlusions in a syringe pump
Assignee: Fresenius SE and Co KGaA
•
Filing: 1992-09-23
•
Granted: 1993-09-07
•
Expires: 2012-09-23
Abstract
Abstract A syringe pump is disclosed in which the pressure in the syringe is monitored. The syringe pump includes a force detector which detects the force on the plunger of the syringe. The force on the plunger of the syringe is converted into a force by means of an algorithm which is independent of the cross-sectional area of the syringe. The algorithm calculates the pressure by subtracting a predetermined frictional force from the measurement force and multiplying the result by a calibration pressure divided by the difference between a calibration force and the predetermined frictional force.
Inventors
- 👤 Nasser Jhuboo
- 👤 Jean-Claude Rondelet
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 22:43
CPC Classifications
A; A61; A61M; A61M5/00; A61M5/14; A61M5/142; A61M5/145; A61M5/1452; A61M5/1456; A61M2205/00; A61M2205/33; A61M2205/332; A61M2205/70
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
71 words
A method of determining the pressure in a syringe used in a syringe pump comprising the steps of: measuring the force on the plunger of the syringe; subtracting a predetermined frictional force (Ff) in the syringe from the measured force to produce a scaled force; multiplying the scaled force by a correction factor dependent on a predetermined calibration pressure (Pc), the predetermined frictional force (Ff) and a predetermined calibration force (Fc).
Claim 2
Independent Claim
71 words
A method of determining the pressure in a syringe used in a syringe pump comprising the steps of: measuring the force on the plunger of the syringe; subtracting a predetermined frictional force (Ff) in the syringe from the measured force to produce a scaled force; multiplying the scaled force by a correction factor dependent on a predetermined calibration pressure (Pc), the predetermined frictional force (Ff) and a predetermined calibration force (Fc).
Claim 3
Dependent Claim
13 words
The method of claim 1 wherein Ff, Fc and Pc are empirically derived.
Claim 4
Dependent Claim
21 words
The method of claim 1 wherein the correction factor is obtained by dividing Pc by the difference between Fc and Ff.
Claim 5
Dependent Claim
28 words
The method of claim 2 wherein Fc is determined by measuring the force on the plunger of the syringe when a pressure of Pc exists in the syringe.
Claim 6
Dependent Claim
29 words
The method of claim 2 wherein Pc is determined by measuring the pressure in the syringe when a force of Fc is applied to the plunger of the syringe.
Claim 7
Dependent Claim
35 words
The method of claim 2 wherein Ff is the frictional force between the wall of the syringe and the stopper of the syringe when the pressure inside the syringe is the same as ambient pressure.
Claim 8
Dependent Claim
29 words
The method of claim 1 further comprising the step of comparing the pressure with a threshold pressure determined to determine whether an occlusion has occurred in the syringe pump.
Claim 9
Dependent Claim
112 words
A syringe pump for pumping fluid from a syringe having a plunger, a stopper and a wall, the syringe pump comprising: means for detecting the force on the plunger; means for converting the force into a calculated pressure using an algorithm; means for storing predetermined pressure values; means for comparing the calculated pressure with a predetermined pressure value; means for informing a user if the calculated pressure exceeds the predetermined value with which the calculated pressure was compared; wherein the algorithm calculates the calculated pressure by subtracting a frictional force from the detected force, multiplying result by a calibration pressure divided by the difference between a calibration force and the frictional force.
Claim 10
Dependent Claim
112 words
A syringe pump for pumping fluid from a syringe having a plunger, a stopper and a wall, the syringe pump comprising: means for detecting the force on the plunger; means for converting the force into a calculated pressure using an algorithm; means for storing predetermined pressure values; means for comparing the calculated pressure with a predetermined pressure value; means for informing a user if the calculated pressure exceeds the predetermined value with which the calculated pressure was compared; wherein the algorithm calculates the calculated pressure by subtracting a frictional force from the detected force, multiplying result by a calibration pressure divided by the difference between a calibration force and the frictional force.
References Cited (Backward Citations)
US4322201A
Cited
US4460355A
Cited
US4747828A
Cited
US4898579A
Cited
US4836752A
Cited
EP0319648B1
Cited
US5047012A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-09-06 | 1997-03-08 | 1997-09-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-09-06 | 2001-03-08 | 2001-09-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-09-06 | 2005-03-08 | 2005-09-07 | $7700.00 | Window Closed / Lapsed |