Liquid purification or separation – Flow – fluid pressure or material level – responsive – Vent control
Patent
1999-01-14
2000-07-11
Drodge, Joseph W.
Liquid purification or separation
Flow, fluid pressure or material level, responsive
Vent control
210188, 21032171, 210647, 96155, 96156, 137 88, 422261, B01D 1712, B01D 1900
Patent
active
060867531
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/SE97/00593, filed on Apr. 10, 1997.
FIELD OF THE INVENTION
The present invention relates to an improvement in a dialysis machine of the type which is described in European Patent No. 278,100 which corresponds to the dialysis machine known as GAMBRO AK 100.
BACKGROUND OF THE INVENTION
In a dialysis machine of the above-mentioned type, one or more cartridges containing sodium bicarbonate powder, sodium chloride or other salts are used. The salt is dissolved by the introduction of water into the cartridge and removal of concentrate from the cartridge. The concentrate is used to prepare the intended dialysis solution.
The composition of the dialysis solution is determined in the dialysis machine by measuring the conductivity of the prepared solution and regulating dosage pumps for each of the various concentrates. It is now common to use two different concentrates; a B-concentrate comprising only bicarbonate from the above-mentioned bicarbonate cartridge, and an A-concentrate comprising the remaining components in concentrated form, for example to a 37-fold concentration. Other combinations of concentrates also exist, such as the B-concentrate, which besides bicarbonate, may also comprise sodium chloride. Alternatively, the B-concentrate can be divided into two parts comprising bicarbonate and sodium chloride, respectively, whereby the A-concentrate comprises the remaining components in a more concentrated form.
By preparing the bicarbonate concentrate and, where appropriate, the sodium chloride concentrate on demand in the dialysis machine, an advantage is realized in that the bicarbonate concentrate remains stable until it is used in a dialyser connected to the dialysis machine.
If a dialysis solution is prepared in advance, which is also now a common procedure, the risk exists that the bicarbonate can decompose to carbon dioxide and carbonate. This implies that the pH value for the solution rises and the risk of precipitation of the calcium carbonate arises during mixing to the prepared dialysis solution. This can affect the final composition of the dialysis solution (reduction of the calcium ion concentrate) as well as creating problems of silting up of conduits and components in the dialysis machine due to the deposition of calcium carbonate. For these reasons, the bicarbonate cartridge as described above has attained widespread use.
As mentioned above, the dialysis solution is prepared by mixing the two concentrates with water. The mixing process is regulated by conductivity meters which control various dosage pumps. Conductivity meters are, however, sensitive to possible incorporation of gas bubbles in the solution. Thus, the conductivity meters are generally preceded by gas separators whereby more accurate, less fluctuating measuring values can be obtained.
The dialysis machine is provided with a monitoring system which is separated from the regulating system and serves to emit alarm signals should error situations arise. In the above-mentioned dialysis machine; namely, GAMBRO AK 100, monitoring of the dosage of concentrate occurs by monitoring the number of revolutions of the dosage pumps. If the number of revolutions differs too greatly from an expected value, an alarm signal is emitted.
When using the above-mentioned bicarbonate cartridge containing dry bicarbonate powder, it is necessary that the powder be wetted with water prior to use. This takes place in a particular "priming step". Water is introduced into the cartridge at its upper end at the same time that a substantial vacuum is applied to the lower end of the cartridge. Water thus fills substantially the entire cartridge in less than a minute.
When a sensor positioned downstream of the bicarbonate cartridge detects that primarily concentrate is flowing from the cartridge, the sensor indicates that the priming step is complete. A valve then switches over the machine so that the substantial vacuum is terminated. This sensor can be the above-mentioned conductivity meter.
During the priming step, a small q
REFERENCES:
patent: 4784495 (1988-11-01), Jonsson et al.
patent: 5779357 (1998-07-01), Jonsson et al.
Dialog Information Services, File 350, Dialog accession No. 002556364, WPI accession No. 80-74387C/42, Nissho KK: "Bicarbonate-type dialysis soln. mfr,-includes heating and degassing the diluting soln. and opt. the conc. solns. prior to mixing" & JP,A, 55115819, 800906, 8042 (Basic), Undated.
Ericson Bjorn
Fang Ji Jun
Hobro Sture
Linderup Erik
Drodge Joseph W.
Gambro Med Tech AB
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