Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Mechanical measurement system
Reexamination Certificate
2001-03-16
2004-12-21
Shah, Kamini (Department: 2863)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Mechanical measurement system
C604S067000, C604S155000
Reexamination Certificate
active
06834242
ABSTRACT:
FIELD OF THE INVENTION
The invention concerns a method for analysis of the pressure variation in a perfusion device including several perfusion modules each equipped with a pump to impel a liquid to be perfused in a line placed downstream from the pump as well as means for measuring the pressure in the line, with junction points enabling connection of certain lines with each other or certain lines with lines originating in units external to the perfusion device as well as a perfusion device for implementation of the process.
BACKGROUND OF THE INVENTION
Perfusion devices usually include a source of liquid connected to a flexible tube which is extended by a cannula or a catheter designed to be inserted into the patient's body. To ensure a controlled flow rate of the liquid, it is common to place a pump along the tube. This pump, when it is of the syringe type, also contains the source of liquid.
When multiple products are to be injected, it is sometimes necessary to use a plurality of these perfusion units. The lines from certain pumps may be connected to each other to allow mixing of different products. The different units are equipped with control means which can trigger alarms or even interrupt the perfusion when certain control criteria are verified.
Proper progress of the perfusion may, in certain cases, be vital. It is thus imperative that the product be administered in accordance with the intended administration plan.
However, incidents sometimes develop which disrupt the progress of the perfusion of one of the products. These incidents are of three types:
an obstruction in the line downstream from the pump;
a rupture of the line downstream or upstream from the pump, or an obstruction upstream from the pump;
a variation in the flow rate in a pump whose line is connected by a junction point with other lines (for example, in the case of a bolus).
These incidents all translate into a variation of pressure in the affected line. Thus, an increase in the pressure in the line k will be noted, for example, in the following cases:
obstruction in the line k;
increase in the flow rate, for example, within the framework of a bolus, in a line j connected to the line k by a junction point.
On the contrary, a reduction in pressure will be noted, for example, in the following cases:
rupture of the line;
reduction in the flow rate in a line j connected to the line k by a junction point.
In the prior art devices, each perfusion unit, or module, is generally equipped with means to monitor and analyze the pressure variations in order to trigger alarms and, as appropriate, to interrupt the perfusion. Thus, if the pressure measured in the line exceeds a certain value, an alarm is triggered and the pump of the affected module is stopped. The user, generally a member of the medical staff, must then determine the cause of the abnormal increase in pressure. If there is no explanation for the increase, for example, this pressure increase is not the result of a manual bolus, it must be concluded that an obstruction has occurred downstream from the pump. However, since the occurrence of the obstruction, the pump has continued to pump until the pressure in the line reaches an alarm value. If the obstruction is eliminated suddenly, all the liquid under excess pressure downstream from the pump and which should have been administered over a certain period of time is delivered abruptly. To prevent such a phenomenon, the pump affected by the obstruction is stopped, then operated in reverse to aspirate the quantity of liquid released since the formation of the obstruction, so as to completely eliminate the bolus. Only at this time can the obstruction be eliminated without danger.
This system of individual detection of pressure for each line from a pump is very effective as long as the affected line is not connected to another line. However, in multiple unit perfusion devices, it is not rare that certain lines are connected in a junction point. If an obstruction develops downstream from such a junction point, the pump whose alarm threshold is the lowest will issue an alarm signal first and will begin to pump in reverse until the disappearance of the excess pressure in its line. However, the other pumps whose lines are connected at the junction point have not yet detected any obstruction because their alarm thresholds have not yet been reached. They thus continue to pump normally, feeding the excess pressure. The pump which is in reverse operation will thus not only aspirate what it delivered after the occurrence of the obstruction, but it will also aspirate the liquid delivered by the other pumps to which it is connected by the junction point. The liquid thus contained in the pump operating in reverse becomes indeterminate and can no longer be used without risk to the patient.
The same increase in pressure which caused the stopping of the pump k may be the result not of an obstruction but rather of a temporary (case of a bolus) or lasting increase in the flow of a line j connected to the line having detected the abnormal increase in pressure. The module k and the perfusion will thus have been interrupted unnecessarily.
SUMMARY OF THE INVENTION
An object of the invention is thus to perfect a process which enables avoiding malfunctions due to the fact that certain lines may be connected to each other.
This object is accomplished by the method in accordance with the invention wherein, when a pressure variation Pk in a line k is detected, an analytical process is implemented to determine the involvement of other modules j in this pressure variation. This process enables consideration of the environment of the affected module before acting, taking into account data from either another module or external data. For this, the modules must be able to communicate either among each other or with a base unit combining all the data and retransmitting them to the modules which may be affected by the data. The analytical process is launched both in the event of increase and in the event of decrease of pressure. Its objective is to analyze the environmental situation of the module affected, in order, depending on the results provided by this analysis, either to avoid an unnecessary interruption of the perfusion if the cause of this variation is explained (variation of the flow rate in a module connected by a junction point, manual bolus at a junction point with the affected line) or to simultaneously stop all the pumps affected by an obstruction or a rupture.
In a first variant, the process includes a search for data indicating a change in the flow rate in another module j. When the flow rate in one line is modified, the affected module sends out, automatically or on demand, a message concerning the modifications made. If a module k detects a pressure variation in its line, it searches for such a message. If it finds one, it will conclude that the pressure variation has a known explanation.
In a further development of this first variant, the analytical process provides, when a message indicating a modification of the flow rate in another module j has been found, for modification of the analytical parameters of the module k for at least the time the modification of flow in the module j lasts. Thus, if the module k notes that the flow rate has been increased in a second module, it modifies its analytical parameters such that it is no longer in an alarm situation. This modification may be of short duration, for example, the duration of a bolus, or lasting, if the increase in flow rate is prolonged. This process is of interest to prevent stopping the perfusion unnecessarily.
According to a second variant, the analytical process includes comparison of the slope of the pressure curve of each line i of the system with the slope of the pressure curve of the line k to determine the lines j which are potentially connected to the line k by a junction point and which may also be affected by the pressure variation. If, in a line j, a pressure increase similar to the pressure increase in the line k is noted, it is probable that the
Rondelet Jean-Claude
Wolff Rémi
Fresenius Vial SAS
Shah Kamini
Westerman Hattori Daniels & Adrian LLP
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