Liquid purification or separation – Processes – Including controlling process in response to a sensed condition
Patent
1996-08-16
1998-08-11
Drodge, Joseph W.
Liquid purification or separation
Processes
Including controlling process in response to a sensed condition
738659, 210 87, 210 90, 210646, 210929, 364510, 604 4, B01D 6130, B01D 6510
Patent
active
057923671
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a system and method for monitoring a fluid flow in a dialysis machine. More specifically, the present invention relates to a back-up system for monitoring the correct operation of dialysis fluid flow rates and/or ultrafiltration volume measurements in a dialysis machine.
BACKGROUND OF THE INVENTION
The present invention is described below in relation to a known dialysis machine, namely the GAMBRO AK-100. Such a dialysis machine is described, for example, in European Patent Nos. B1-0 204,174 and B1-0 204,260.
The dialysis machine comprises a first part for preparing, mixing and conditioning a dialysis fluid, and a second part for supplying the fluid to a dialyzer and for controlling and monitoring the flow. The second part comprises two constant flow regulators positioned upstream and downstream, respectively, of the dialyzer.
Each flow regulator comprises a restrictor, a pressure sensor and a pump. The pressure sensor controls the pump in such a way that the pressure between the restrictor and the pump remains substantially constant. Since the inlet pressure upstream of the one throttle device and the outlet pressure downstream of the other restrictor or throttle device is substantially constant, a constant pressure drop over the respective restrictor is obtained, which means that there is a constant flow therethrough.
In hemodialysis, hemofiltration and hemodiafiltration an amount of fluid is separated from the blood flow by the filter which is used. This means that the flow downstream of the filter will be somewhat larger than the flow upstream of the filter. This ultrafiltration is adjusted by the above-referenced flow regulators. There are also other ways of achieving ultrafiltration, for example by adjusting the flow regulators to the same value and removing a separate ultrafiltration flow by means of a separate pump.
The remaining elements of this dialysis machine are disclosed in the aforesaid European Patent No. B1-0 204,174, to which reference is now made, and the disclosure of this is incorporated herein by reference thereto.
The adjustment and regulation of the dialysis machine is described in more detail in European Patent No. B1-0 204,260. Briefly, adjustment implies that a desired ultrafiltration is set by electrical adjustment devices. Additionally, a desired flow rate is set for the dialysis fluid, for example 300 ml/minute, 500 ml/minute or 700 ml/minute. The set values are supplied to a regulating computer which calculates and/or supplies set values for pressure in the pressure sensors of the flow regulators. The pressure set values are then continually adjusted in the regulating computer depending on the measured values of flow which are obtained in a separate flow measurement arrangement.
Generally, the regulating computer includes a first feed-back loop from the pressure sensors to the pumps.
Moreover, the regulating computer includes the pressure sensors in a second feed-back regulating loop maintaining the pressure at the desired value.
The first feed-back loop has a fast response and thus immediately compensates for any possible variations in the pressure, as well as any possible pressure surges in the system. The change of the set values for the pressure sensors in the second feed-back loop takes place slower.
In order to increase the safety of the system in the dialysis machine, two separate microcomputers are used, one monitoring computer and one regulating or controlling computer. Further characteristics of the adjustment arrangement are disclosed in the aforesaid European Patent No. B1-0 204,260.
The accuracy of the aforesaid system is dependent on the measurement accuracy of the flow measurement device. This flow measurement device is basically constructed as is disclosed in either of British Patent No. 2,003,274 or European Patent No. B1-0 106,940.
The measurement device consists of two measuring cells, through which fluid flows pass into and out of the dialyzer. There is a magnetic field perpendicular to the measuri
REFERENCES:
patent: 4370983 (1983-02-01), Lichtenstein
patent: 4585552 (1986-04-01), Gummesson et al.
patent: 4762618 (1988-08-01), Gummeson et al.
patent: 5342527 (1994-08-01), Chevallet et al.
patent: 5580460 (1996-12-01), Polaschegg
J. Phys. E: Sci. Instrum., vol. 15, 1982, T J S Brain et al., "Survey of pipeline flowmeters" pp. 968-971.
Technisches Messen tm, vol. 52, No. 1, 1985, D. Meyer et al., "Erfahrungen beim Einsatz von Durchfluss-und Mengenmessern in der chemischen Industrie," pp. 13-14.
Mattisson Leif
Wejfeldt Gunilla
Drodge Joseph W.
Gambro AB
LandOfFree
System and method for monitoring a flow of dialysis fluid in a d does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with System and method for monitoring a flow of dialysis fluid in a d, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and System and method for monitoring a flow of dialysis fluid in a d will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-385847