JP3319683B2 - Liquid level control method for drip chamber connected to extracorporeal blood circulation circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for discharging a fluid by controlling a liquid level in a drip chamber to a set level.

[0002]

2. Description of the Related Art When blood is circulated outside the body to perform necessary processing on blood, a drip chamber is connected in the middle of a blood circuit. The drip chamber stores a fixed amount of air and keeps the liquid level constant so that the state of blood circulation can be visually confirmed from the outside. Blood can be dropped into the air to observe the blood circulation.

[0003] A drip chamber connected in the middle of a blood circuit circulating outside the body is used in an airtightly closed manner.
Air is stored in the upper part and used at a predetermined liquid level. The airtightly closed drip chamber discharges the same amount of blood as the supply, so that the liquid level does not fluctuate. When the drip chamber is used, it is necessary to adjust the liquid level to a set level.
In blood purification therapy in which blood is circulated through the body, the blood circuit is washed with physiological saline before starting treatment, that is, the blood circuit is primed. During priming, the liquid level in the drip chamber is adjusted. If the fluid level is adjusted during priming, the fluid level in the drip chamber will not change, even if the circulating fluid is replaced by saline to blood.

In order to adjust the drip chamber liquid level to a set level during priming, a conventional method uses a drip chamber liquid level sensor. The liquid level sensor detects the liquid level of the drip chamber, and for example, a capacitance sensor or an ultrasonic sensor is used. The method using the liquid level sensor adjusts the liquid level of the drip chamber to a set value as described below.

[0005] The discharge valve is closed and the air valve is opened. Operate the pump until the drip chamber liquid level reaches the set level. A liquid level sensor detects whether the liquid level in the drip chamber has reached the set level. When the drip chamber liquid level reaches the set level,
Close the air valve and open the discharge valve. When the pump is operated in this state, the drip chamber can discharge the supplied fluid while maintaining the liquid level at a constant level.

[0006]

As described above, the conventional method of adjusting the liquid level at the time of priming uses a capacitance sensor or an ultrasonic sensor as the liquid level sensor, so that the liquid level sensor is expensive. There is a disadvantage. Further, when the distance between the capacitance sensor and the drip chamber is shifted, the liquid level cannot be accurately detected. The farther the capacitance sensor is from the drip chamber,
This is because the detection sensitivity decreases. Further, this sensor has a drawback that when the drip chamber is touched by a hand or the like, the capacitance fluctuates and the detection cannot be performed accurately. The ultrasonic sensor has a disadvantage that the liquid level cannot be accurately detected unless the ultrasonic sensor is in contact with the drip chamber.

[0007] The present invention has been developed for the purpose of further solving this drawback. An important object of the present invention is to provide a drip chamber liquid connected to an extracorporeal blood circulation circuit that can control the drip chamber liquid level to a set level with an inexpensive structure without using a capacitance sensor or an ultrasonic sensor. An object of the present invention is to provide a surface control method.

[0008]

According to the present invention, a liquid level control method for a drip chamber connected to an extracorporeal circuit is provided by supplying a fluid to a drip chamber connected to an extracorporeal circuit. To a set level,
In this state, the discharge valve is opened to improve the method of controlling the liquid level at which the supplied fluid is discharged from the discharge valve.

According to the method of controlling the liquid level of a drip chamber connected to an extracorporeal blood circulation circuit of the present invention, the extracorporeal circulation circuit is not substantially expanded by pressure, and a discharge valve connected to the drip chamber 1 is provided. The fluid is supplied to the drip chamber 1 with the valve 3 and the air valve 4 closed. In this state, the pressure sensor 5 detects that the pressure of the drip chamber 1 has risen to the set pressure.
When the liquid level of the drip chamber 1 rises to the set level, the supply of fluid is stopped, the air valve 4 is opened, and the compressed air stored in the drip chamber 1 is discharged by the air valve 4. When it is detected that the inside of the drip chamber 1 has become non-pressurized, the air valve 4 is closed and the discharge valve 3 is opened. Thereafter, a fluid is supplied to bring the drip chamber 1 into a predetermined liquid level. The fluid is discharged from the discharge valve 3 while maintaining the level.

The extracorporeal circuit used in the method of the present invention is illustrated in FIG. In the extracorporeal circuit shown in this figure, fluid is supplied to the drip chamber 1 by the pump 2. The pump 2 includes a blood pump 2A for transferring blood and a plasma pump 2B for transferring plasma. Blood pump 2A and plasma pump 2B
The device for supplying a fluid to the drip chamber 1 by the pump 2 comprising the drip chamber 1 stops the operation of the pump 2 when the pressure of the drip chamber 1 rises to the set pressure and the liquid level of the drip chamber 1 rises to the set level. When the pump 2 of both the blood pump 2A and the plasma pump 2B
Stop operation of. Thereafter, the operation of the pump 2 was stopped, the air valve 4 was opened, the pressurized air stored in the drip chamber 1 was discharged by the air valve 4, and the drip chamber 1 was in a non-pressurized state. Is detected, the air valve 4 is closed, the discharge valve 3 is opened, and the pump 2 to be operated thereafter is either the blood pump 2A or the plasma pump 2B, or both.

The circuit shown in FIG.
The control circuit 9 controls the on-off valve 11 to open and close the on-off valve 11 to control the supply of fluid to the drip chamber 1. The device that opens and closes the on-off valve 11 can adjust the supply of fluid to the drip chamber 1 by opening and closing the on-off valve 11 while the pump 2 is operating.

[0012]

FIG. 1 shows a preferred process of controlling the liquid level of the drip chamber to a set level by the liquid level control method of the present invention. The liquid level control method shown in this figure controls the liquid level of the drip chamber to a set level as described below.

(1) Opening the air valve 4 and the discharge valve 3
The fluid is supplied to the drip chamber 1. The fluid is supplied to the drip chamber 1 by opening the on-off valve 11 and operating one or both of the blood pumps 2A and the plasma pump 2B. Physiological saline is used for the fluid. The fluid supplied from the pump 2 is discharged from a discharge valve 3 connected to a lower end of the drip chamber 1. In this state, since the air valve 4 and the discharge valve 3 are opened, the drip chamber 1 is not pressurized by the supplied fluid.

(2) The liquid sensor 6 detects the passage of the fluid and closes the discharge valve 3 and the air valve 4. The pump 2 supplies a fluid to the drip chamber 1 with the discharge valve 3 and the air valve 4 closed to hermetically seal the drip chamber 1. The hermetically sealed drip chamber 1 is pressurized with the supplied fluid. Further, the supplied fluid is stored in the drip chamber 1 and the liquid level rises. The level position is a function of the pressure in the drip chamber 1. For example, when a fluid is pressed into half of the volume including the drip chamber 1 which is hermetically sealed,
Since the volume of the fluid does not change, the internal pressure of the drip chamber 1 increases by about 1 atm. This is because the product of the volume of the pressurized air and the pressure becomes constant. Therefore, by detecting the internal pressure of the drip chamber 1, it can be detected that the liquid level of the drip chamber 1 has reached the set level.

(3) When the liquid level of the drip chamber 1 reaches the set level and the internal pressure reaches the set pressure, the pressure sensor 5 detects this and stops the supply of the fluid to the drip chamber 1. To open the air valve 4. In order to stop supplying the fluid to the drip chamber 1, the operation of the blood pump 2A and the plasma pump 2B is stopped, or the on-off valve 11 is closed. In this state, the discharge valve 3 is kept closed. The pressurized air in the drip chamber 1 is exhausted from the opened air valve 4, and the internal pressure of the drip chamber 1 becomes the atmospheric pressure. (4) Close the air valve 4 and open the discharge valve 3 to supply the fluid to the drip chamber 1. To supply the fluid, one or both of the blood pump 2A and the plasma pump 2B are operated, and when the on-off valve 11 is closed, the on-off valve 11 is opened. Drip chamber 1
Since the air valve 4 is closed, the liquid level is maintained at the set level, and the supplied fluid is discharged from the discharge valve 3.
That is, the liquid level in the drip chamber 1 is maintained at the set level, and the fluid is discharged.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. However, the following examples illustrate a method for embodying the technical idea of the present invention, and the present invention describes a method for controlling the liquid level of a drip chamber connected to an extracorporeal blood circulation circuit. Not specific to the method.

Further, in this specification, in order to make it easy to understand the claims, the numbers corresponding to the members shown in the embodiments will be referred to as "claims" and "claims". In the column of “means”. However, the members described in the claims are not limited to the members of the embodiments.

FIG. 2 is a schematic view of an apparatus used in the liquid level control method of the drip chamber connected to the extracorporeal blood circulation circuit of the present invention. The drip chamber 1 in this figure is
It is connected to the blood circuit. In this figure, the drip chamber 1 is connected to the blood return side of the blood circuit. However,
The drip chamber is connected to the blood collection side of the blood circuit or in the middle of the circuit. A drip chamber connected to the circuit prevents air and clotted blood from entering the body. Further, by dropping blood into the air of the drip chamber, the flow speed of blood can be checked.

The drip chamber is also used in a circuit for infusing an infusion into the body via a catheter. The drip chamber used for this purpose can also prevent air from entering the body and check the infusion supply.

FIG. 3 shows a detailed view of the blood circulation circuit of FIG. The blood circulation path shown in these figures is provided with a filter 7 for sucking blood by the blood pump 2A on the blood collection side and separating plasma.
To supply. The filter 7 separates plasma and other components. The separated plasma is supplied to the adsorber 10 for removing pathogenic substances in the plasma and the final filter 8 by the plasma pump 2B. The plasma that has passed through the final filter 8 passes through the on-off valve 11 together with components other than the plasma separated by the filter 7, is supplied to the drip chamber 1, and is returned from the drip chamber 1 into the body.

The circuits shown in these figures prime with flowing saline before circulating blood for washing. When priming, drip chamber 1
Adjust the liquid level to the set level. Drip chamber 1
In order to adjust the liquid level to a set level, the drip chamber 1 has a discharge valve 3 connected to a lower end, and an air valve 4 and a pressure sensor 5 connected to an upper end. Further, a liquid sensor 6 is also connected to the discharge side of the drip chamber 1.
Air valve 4, discharge valve 3, blood pump 2A and plasma pump 2
B and the on-off valve 11 are controlled by the control circuit 9 to adjust the liquid level of the drip chamber 1 to a set level.

The control circuit 9 has a built-in microcomputer. The control circuit 9 calculates input signals from the pressure sensor 5 and the liquid sensor 6 and calculates the air valve 4 and the discharge valve 3.
Is opened and closed, and the operation of the pump 2 composed of the blood pump 2A and the plasma pump 2B or the opening / closing valve 11 is controlled to adjust the liquid level of the drip chamber 1 to a set level. The control circuit 9 adjusts the liquid level of the drip chamber to a set level according to the flowchart of FIG.

[Step N1] The control circuit 9 opens the air valve 4 and the discharge valve 3. [Step N2] The control circuit 9 operates the pump 2 including the blood pump 2A and the plasma pump 2B. The pump 2 including the blood pump 2A and the plasma pump 2B supplies physiological saline to the filter 7, the adsorber 10, the final filter 8, and the drip chamber 1. At this time,
The on-off valve 11 is opened.

[Step N3] The liquid sensor 6 detects whether physiological saline has passed through the discharge side of the drip chamber 1, and inputs a detection signal to the control circuit 9.
This step is looped until the liquid sensor 6 detects saline. [Step N4] When the physiological saline flows to the discharge side of the drip chamber 1, the liquid sensor 6 detects this, and the control circuit 9 closes the discharge valve 3.

[Step N5] The pressure sensor 5 determines whether or not the internal pressure of the drip chamber 1 is equal to the atmospheric pressure, that is, whether or not the pressure difference from the atmospheric pressure is 0 kg / cm ^{2 in} a non-pressurized state. . With the discharge valve 3 opened,
The physiological saline supplied to the drip chamber 1 passes through the discharge valve 3 and flows down naturally and is discharged. For this reason,
When the saline is supplied by opening the discharge valve 3, the internal pressure of the drip chamber 1 becomes negative pressure, that is, lower than 0 kg / cm ² . When the physiological saline is supplied by closing the discharge valve 3, the physiological saline does not flow down through the discharge valve 3, so that the pressure in the drip chamber 1 rises to the atmospheric pressure. This step is looped until the internal pressure of the drip chamber 1 becomes the atmospheric pressure.

[Step N6] Drip chamber 1
When the internal pressure of the air becomes atmospheric pressure, the air valve 4 is closed. When the air valve 4 and the discharge valve 3 are closed, the drip chamber 1
Are hermetically closed. In this state, since the pump 2 including the blood pump 2A and the plasma pump 2B supplies the physiological saline to the drip chamber 1, the internal pressure of the drip chamber 1 starts to increase.

[Step N7] After closing the air valve 4, a timer built in the control circuit 9 starts counting. The control circuit 9 is provided to determine whether the time required for the internal pressure of the drip chamber 1 to reach the set pressure is within a specified range, and to determine whether the system is operating normally.

[Step N8] The pressure sensor 5 detects the internal pressure of the drip chamber 1 and loops this step until the internal pressure of the drip chamber 1 reaches the set pressure. The set pressure is stored in the memory of the control circuit 9.
The stored set pressure is the pressure at which the liquid in the drip chamber 1 rises to the set level, for example, 350 m
It has been adjusted to mHg. However, it goes without saying that the method of the present invention does not specify the set pressure to this value. The set pressure is set to an optimum value depending on the shape of the drip chamber and the required liquid level. When the liquid level of the drip chamber 1 rises to the set level, the internal pressure of the drip chamber 1 rises to the set pressure.

[Steps N9 and N10] When the internal pressure of the drip chamber 1 rises to the set pressure, the timer stops counting and stops supplying the physiological saline. In order to stop the supply of the physiological saline, the operation of the pump 2 including the blood pump 2A and the plasma pump 2B is stopped. Without stopping the operation of the pump, the on-off valve 11 may be closed to stop the supply of the physiological saline. Since the internal pressure of the drip chamber 1 is detected by the pressure sensor 5, the pressure signal of the drip chamber 1 is
Is input to the control circuit 9. Therefore, the control circuit 9
Is the signal from the pressure sensor 5 and the drip chamber 1
, The count of the timer is stopped, the operation of the pump 2 including the blood pump 2A and the plasma pump 2B is stopped, or the on-off valve 11 is closed.

In the above embodiment, both the blood pump and the plasma pump are operated to supply the physiological saline to the drip chamber. However, one of the blood pump and the plasma pump can be operated to supply the physiological saline to the drip chamber. [Step N11] The control circuit 9 determines whether or not the count value of the timer is within a specified range. If the count value of the timer is not within the specified range, the system is stopped and an alarm is issued. For example, the count value exceeds the specified time when the drip chamber 1 is not completely closed airtight. If there is a leak in the drip chamber 1, air or physiological saline leaks, and the pressure rise slows down. [Step N12] If the count value of the timer is within the specified time range, the air valve 4 is opened. The pressurized air in the drip chamber 1 is exhausted from the air valve 4. [Step N13] This step is looped until the internal pressure of the drip chamber 1 reaches the atmospheric pressure.

[Steps N14, N15, N16] When the internal pressure of the drip chamber 1 becomes atmospheric pressure, the air valve 4 is closed, the discharge valve 3 is opened, and saline is supplied to the drip chamber 1. . To supply the saline to the drip chamber 1, the blood pump 2A whose operation is stopped
And the operation of the pump 2 composed of the plasma pump 2B is restarted.
When the on-off valve 11 is closed, the on-off valve 11 is opened. In this state, the liquid level in the drip chamber 1 is maintained at the set level, and the supplied physiological saline is discharged.
Is discharged through. In this step, one of the blood pump 2A and the plasma pump 2B can be operated.

As a result of adjusting the liquid level of the drip chamber to the set level in the above flowchart, the liquid level was accurately controlled as shown in the following. However, this table shows that the set pressure of the drip chamber in the step of N8 is set to 350 mmHg, the inner diameter of the drip chamber is 17 mm, and the length of the drip chamber is 110 m.
m, and the liquid level was measured based on the lower end of the drip chamber.

65.4 mm 64.7 mm 65.7 mm 61.9 mm 63.1 mm Average 64.2 SD = 1.615

As a result, even if the pump and the on-off valve had variations, the above-mentioned accuracy was obtained, and the liquid level could be adjusted with considerably high accuracy.

In the above embodiment, since the liquid level in the drip chamber is adjusted to the set level at the time of priming, the fluid to be supplied is physiological saline. However, the liquid level control method of the present invention does not specify the fluid supplied to the drip chamber to the physiological saline. The set level can be adjusted by supplying a fluid other than physiological saline, for example, a fluid such as blood or washing water to the drip chamber.

[0036]

The method for controlling the liquid level of the drip chamber connected to the extracorporeal blood circulation circuit according to the present invention does not use a capacitance sensor or an ultrasonic sensor as in the prior art, and is extremely inexpensive. There is a feature that the liquid level of the drip chamber can be adjusted to the set level by using. Unlike the conventional liquid level sensor, the pressure sensor does not need to accurately control the distance to the drip chamber, and there is no effect of detection error even if the liquid level sensor touches the hand. The feature is that the surface can be accurately controlled to the set level.

Further, the method of the present invention has an advantage that in a device for connecting a pressure sensor to the drip chamber for another purpose, the liquid level can be adjusted to a set level using the already connected pressure sensor. A pressure sensor is connected to a drip chamber, which is connected to a blood circulation path for circulating blood outside the body and performing necessary processing on the blood, to accurately detect the pressure of the blood. The pressure sensor is
The blood supply state is controlled to accurately control the blood pressure. For example, when transmitting blood through a filter, it is necessary to adjust the blood pressure to a set pressure. If the pressure deviates from the set value, adverse effects such as deviating the filtering conditions from the optimal conditions or damaging the filtration membrane occur. As described above, in the device in which the pressure sensor is connected to the drip chamber, the liquid level can be controlled to the set level by using the pressure sensor together.
The feature is that the liquid level can be accurately controlled with an extremely simple structure.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of a liquid level control method of a drip chamber connected to a blood extracorporeal circuit according to the present invention.

FIG. 2 is a schematic diagram of a blood circulation circuit used in the liquid level control method of the present invention.

FIG. 3 is a circuit diagram of a blood circulation circuit used in the liquid level control method of the present invention.

FIG. 4 is a flowchart showing a control circuit of the blood circulation circuit shown in FIG. 3 for setting the liquid level of the drip chamber to a set level;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Drip chamber 2 ... Pump 2A ... Blood pump 2B ... Plasma pump 3 ... Discharge valve 4 ... Air valve 5 ... Pressure sensor 6 ... Liquid sensor 7 ... Filter 8 ... Final filter 9 ... Control circuit 10 ... Adsorber 11 ... Open / close valve

Claims (1)

(57) [Claims] 1. A fluid is supplied to a drip chamber (1) connected to an extracorporeal circulation circuit to control a liquid level to a set level, and in this state, a drain valve (3) is opened to be supplied. In a liquid level control method for a drip chamber connected to an extracorporeal circuit for blood discharging a fluid from a discharge valve (3), the extracorporeal circuit connected to the drip chamber (1) is not substantially expanded by pressure. Along with
With the discharge valve (3) and the air valve (4) connected to the drip chamber (1) closed, fluid is supplied to the drip chamber (1), and the pressure of the drip chamber (1) is increased to the set pressure. Is detected by the pressure sensor (5), and when the liquid level of the drip chamber (1) rises to the set level, the supply of fluid is stopped, the air valve (4) is opened, and the air valve is opened. (4) The pressurized air stored in the drip chamber (1) is discharged, and when the inside of the drip chamber (1) is detected to be in a non-pressurized state, the air valve (4) is closed. Together with the drain valve (3), and then the drip chamber
Extracorporeal circulation of blood, characterized in that the fluid is supplied to (1) and the fluid is discharged from the discharge valve (3) while maintaining the drip chamber (1) at a predetermined liquid level. A liquid level control method for a drip chamber connected to a circuit.