JPS6243695B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to extracorporeal hemodialysis, and more particularly to an apparatus for dialyzing a patient's blood using a single venipuncture or cannula.

Kidney disease has important implications for human life. Many types of kidney disease interfere with the function of the kidneys so that the kidneys are unable to remove waste products and excess water from the blood. When the kidneys become exhausted and deteriorating and are no longer able to remove most of the waste products and water from the blood, the patient cannot survive unless an artificial method is provided to replace the function of the deteriorating kidneys. . Many new developments are seeing the light of day regarding the replacement of kidney functions outside the body.

Nevertheless, even with the improved extracorporeal kidney devices that exist, the same general procedures used in the very early treatment of kidney disease are still used in hemodialysis of patients. for example,
The most commonly accepted practice for dialysis of a patient's blood outside the body requires surgical removal of a subcutaneous arterio-venous fistula. The subcutaneous venous system is then further dilated to increase the number of blood vessels channeled from the artery to the vein through the fistula. The vein is then punctured using a large diameter needle.
Enable sufficient blood flow for dialysis. Two venipunctures are made in the patient's vein, usually using two hollow needles or cannulas with lumen stylets, so that two blood-connection sites are present in the patient's blood vessel at the same time. Typically, blood is drawn from one punctured vein and passed through a hemodialyzer before being pumped into the other vein.

The above implementation has proven to be extremely disadvantageous for both the patient and the attending physicians and technicians. This problem is particularly disadvantageous since most patients requiring extracorporeal hemodialysis must undergo the procedure three to seven times per week.
This means that even if all venipunctures are completely successful, patients will need to undergo 6 to 12 venipunctures or cannulations each week.

The duration and good functioning of a fistula created by venipuncture is inversely related to the number of venipunctures. Tissues that have suffered repeated venipuncture trauma become highly susceptible to thrombophlebitis, perivenous bleeding, blood clots, and infection. The tissue surrounding the most susceptible veins develops into large hematomas that obscure the veins and make successful venipuncture extremely difficult due to insufficient blood flow in the injured vessel. It is true that this is common in patients who have undergone many venipunctures.

Also, a fact that pertains to the above problem is that once the first venipuncture was successful and the blood flowed from the patient's body to the hemodialyzer, when the blood volume in the patient's body decreased, the second venipuncture was performed successfully. Puncture may become very difficult.

Although a very skilled surgeon or technician can perform a first venipuncture without much difficulty, it often takes a number of attempts before a second venipuncture can be performed on the same patient. I also understood.

Furthermore, although the pain and discomfort experienced by the patient may be understandable, it is often necessary to insert a second needle after several venipuncture attempts, which can increase anxiety. and,
Anxiety on the part of both the patient and the physician or technician attending the patient further reduces the likelihood of successful venipuncture.

It has been found that the results of single fistula dialysis are significantly improved by increasing the stroke capacity of the dialysis system. In the present invention, the volume of one stroke is the velocity of blood flow (ml/
minutes) divided by the number of cycles per minute of the blood flow control system. Increasing the stroke capacity means that the efficiency is improved because common mixing during one fistula tube dialysis is reduced.

Some systems use pressure monitors or time-controlled clamps to control blood flow from the patient to the dialyzer and then back from the dialyzer to the patient. In such systems, care was taken to maintain the velocity of blood flow from the patient essentially equal to the velocity of blood flow in the line returning to the patient. If the arterial line (blood flow removed from the patient) and the venous line (blood flow returned to the patient) have the same flow rate, the stroke volume cannot always be maximized. It will be appreciated that an increase in blood flow velocity also requires a corresponding increase in cycles per minute of the blood flow control system per minute.

In accordance with the present invention, various novel devices are provided that maximize the efficiency of hemodialysis in terms of stroke volume.

Although the present invention is applicable to a variety of extracorporeal hemodialysis systems, it currently has the most significant advantages for dialysis through a single venipuncture. Generally, once a venipuncture is performed, blood is removed from the venipuncture site and directed through the arterial branch of the Futamata blood pathway at a pressure low enough to prevent injury to the arterial branch or the patient's blood vessels. . A futamata is placed next to the needle coupling to minimize the creation of dead space.
The blood is then pumped under pressure into an extracorporeal hemodialyzer while the venous branch is closed. Thereafter, the venous branch of the Futamata blood flow path is opened for a predetermined period of time to allow blood to return to the venipuncture site. The time for returning blood in the venous branch is controlled such that the returning blood flow rate is different from the blood flow rate in the arterial branch. The use of a single venipuncture method is enabled by alternately introducing and withdrawing blood from the patient's blood vessels at the venipuncture site. For example, blood may be drawn from the patient at pressures that do not damage the patient's blood vessels or arterial branches, allowing pulsating blood to flow in only one direction to the dialyzer. Meanwhile, the venous branches are closed so that the pressure builds up in the dialyzer. In a preferred example, blood is returned to the patient for a predetermined period of time at a flow rate that is substantially higher than the flow rate at which it was withdrawn.

According to the present invention, a single hollow cannula is inserted into a patient's blood vessel, the cannula is branched into an arterial branch and a venous branch outside the body, and a hemodialyzer is positioned between these branches. the venous branch for a first variable time increment and simultaneously pass the arterial branch from the patient's blood vessel into the dialyzer until the blood in the venous branch reaches a predetermined elevated blood pressure. the arterial branch and open the venous branch for a second predetermined time course that is shorter than the first variable time course, thereby reducing the elevated blood pressure. A method is provided for dialyzing blood in a patient with an extracorporeal hemodialysis device, the method comprising: directing blood in an intravenous line to the patient at a faster flow rate than the same amount of blood is drawn from the patient. .

Further in accordance with the present invention, blood is drawn from the patient through the arterial line at a flow rate that does not damage the blood-conduit, and the venous line is closed while blood is continued to be drawn from the patient until the venous line reaches a predetermined elevated blood pressure. , then opening the venous line and essentially simultaneously closing the arterial line and injecting blood under pressure into the patient for a predetermined period of time, and the duration of the venous line opening being the duration of the arterial line opening. an arterial line that leads blood taken from the patient, a venous line that leads blood toward the patient, and a dialysis line that is located between the arterial line and the venous line A method is provided for controlling an extracorporeal hemodialysis system consisting of a blood flow pump that moves blood in only one direction.

A hemodialysis control device according to the invention comprises an arterial line for conducting blood removed from a patient, a venous line for conducting blood towards the patient, and a dialyzer positioned between the arterial and venous lines. A means of pumping blood from a patient in only one direction through an open arterial line at a non-damaging pressure, a means of closing the venous line while pumping blood until the venous line reaches a predetermined elevated blood pressure, independent of time. a closure means comprising a blood pressure-responsive control means adjustable to maintain closure of the venous line and a means for opening the venous line and essentially simultaneously closing the arterial line, the pressure in the venous line for a predetermined period of time; an opening means having a time-responsive control means adjustable to maintain the venous line open and infuse blood under pressure into the patient independently of the duration of the occlusion of the arterial line; Contains an improvement characterized by a shorter duration.

Another aspect of the invention as described above is a device for pumping blood from a patient in only one direction through an open arterial line at a pressure that does not damage the blood conduit, and for closing a venous line while pumping the blood. a first independently variable control means for maintaining the venous line closed until the venous line reaches a predetermined blood pressure, opening the venous line and essentially simultaneously opening the arterial line; a second independently variable control means for closing and injecting blood into the patient for a predetermined period of time during which the accumulated blood pressure is closed; It includes an improvement characterized by a longer duration than the

Embodiments of the present invention will be described by way of example with reference to the accompanying drawings. Hollow cannula 24 is adapted to reside within a patient's blood vessel. Preferably, the cannula is inserted according to any suitable technique, such as venipuncture. canyule 2
4 may have any suitable shape; one suitable cannula is a 2 mm internal diameter catheter having a length between 2.5 and 5 cm. It is also preferred to use a hollow needle or any other suitable hollow device that can be effectively inserted into a vein. As used herein, cannula refers to any hollow tube that can be inserted into a blood vessel of a patient.

In one embodiment illustrated in the drawings, the cannula 24 is bifurcated at a coupling 28. Connector 28 has an arterial branch and a venous branch which is attached to rubber or plastic tubing 34 in a conventional manner. This tube is hereinafter referred to as arterial line 34.

Arterial line 34 is positioned above the blood pump surface, shown generally at 38. Blood pump 38 is conventional and typically
It includes a rotatable shaft 40 mounted on a crossbar 42. The crossbar 42 has rotatable cylinders 48 and 50 at each end thereof. Approximately half of the circular passageway traversed by cylinders 48 and 50 is bordered by a semicircular passageway 52. Arterial line 34 runs along the inner surface of semicircular passageway 52. Thus, as cylinders 48 and 50 pivot in circular passages about the axle of shaft 40, arterial line 34 is compressed between each cylinder and semicircular passage 52. Normally, the crossbar 42 is rotated clockwise about the axis 40 so that a compressed portion of the arterial line 34 occurs between the cylinder and the semicircular passageway 52 at the anterior end of the semicircular passageway. , and proceed towards the entire inner surface of the semicircular passageway towards its rear end. As the compressed portion of the arterial line 34 travels over the inner surface of the semicircular passageway 52, the blood in the arterial line 34 is forced into the dialyzer, shown generally at 60. The cylinder 48 is a semicircular passage 52
When the rear end of the cylinder 50 is reached, the cylinder 50 engages the arterial line 34 at the front end so that as long as the pump is working, a constant pressure is applied to the blood to move the blood forward to the dialyzer 60. I know what will happen.

Any suitable conventional dialyzer can be used in the system of the present invention. Blood exits dialyzer 60 and enters venous line 62, which is attached to one branch of connector 28 in the conventional manner. An air bubble trap 64 is placed between the intravenous line 62 and the air bubbles in the cannula 24.
Preferably, it is prevented from passing through the blood vessels. Bubble trap 64 may be any suitable conventional bubble trap, such as those used with blood infusion devices.

The pressure conducting tube 66 is connected to an intravenous line, preferably above the blood surface level 68, to a drip chamber, such as a bubble trap 64. Therefore, bubble trap 64 and intravenous line 62
The pressure within can be transmitted through pressure conduction tube 66 into a controller, shown generally at 70. The controller 70 includes (a) a pressure monitor, which may be of any suitable type, and (b) a temporal circuit, which may also be of any suitable type.

The controller 70 has a glass rim 8 on which a scale is provided, for example with a display expressed in mmHg.
It has 2. The indicator 84 is controlled by the pressure of the intravenous line in the pressure conducting tube 66, and as the intravenous line pressure in the pressure conducting tube 66 increases, the indicator 84 increases to indicate the pressure in mmHg. Similarly, as the pressure in the pressure conduit 66 drops, the reading on the indicator 84 drops to indicate the decrease in pressure in mmHg. The manually adjustable set point is determined by the location of the landmark 88. For example, a case where the mark 88 is set to the upper limit of the pressure in the intravenous line 62 will be described in more detail.

Once set point 88 corresponds to the maximum pressure in venous line 62, clasp 150 is moved to open venous line 62 and close arterial line 34, as described in detail below. The intravenous line 62 is connected at a predetermined time.
increment) and then closed again. The time course is determined by an adjustment dial 86 on the controller 70. any suitable time range may be included, but
A time course between 0.5 seconds and 1.5 seconds was found to be suitable for most single fistula systems.

One embodiment illustrated in the figures includes dual clamps 150. Clamp 150 has intersecting grooves 152 and 154 through which venous and arterial lines 6 are routed.
2 and 34 have passed through, respectively. Clamp 150 has a catch 156 positioned between grooves 152 and 154. Claps 156 alternately selectively actuate into grooves 152 or 154 to close or open the arterial and venous lines. The control of the catch is provided by an electric conductor connecting the clamp 150 to the controller 70.
160 and 162.

First, the set point on controller 70 is set at landmark 88.
is adjusted by moving the venous pressure to indicate the desired venous pressure. Arterial and venous lines are prefilled with isotonic saline. If a single venipuncture or cannula insertion is performed, the saline in arterial line 34 and venous line 62 will be replaced with blood.

Pump 38 operates continuously to pump blood toward dialyzer 60 . The speed of the blood pump is selected to be the maximum speed that does not damage the arterial line 34 or the patient's blood vessels.

When venous line 62 is closed by clamp 150, blood is withdrawn from the patient's blood vessels and pumped through cannula 24 and arterial line 34 to dialyzer 60. As pump 38 continues to operate, the pressure in venous line 62 increases due to the venous line in groove 152 being closed. As the pressure increases, indicator 84 rises to a set point defined by landmark 88. Once the set point is reached, clamp 150 moves to open venous line 62 and essentially simultaneously close arterial line 34.

the arterial line 34 for a predetermined period of time;
It is important to select, with adjustment dial 86, the time lapse of closure to be just long enough to reduce venous pressure by injecting blood into the patient through cannula 24. . It has been found that the time required for a given amount of blood to return to the patient through the venous line is proportional to the pressure developed above the blood in the venous bubble trap 64. Therefore, the higher the pressure combined at landmark 88, the shorter the time course for opening the intravenous line. According to this embodiment of the invention, it is necessarily preferred that the time course during which the intravenous line is open is shorter than the time course during which the intravenous line is closed. In a preferred embodiment, for example, it is advantageous to maintain a 2:1 ratio of the opening time of the arterial line to the opening time of the venous line. The rate of flow delivered to the patient through the intravenous line depends on how much pressure builds up in the intravenous bubble trap 64 while closing the intravenous line.

In the embodiments described above, the pressure in the dialyzer 60 may be maintained low while emphasizing a higher flow rate in the venous line 62 than in the arterial line 34. is sometimes desirable. In this case, it is more desirable that the velocity of blood exiting through arterial line 34 be greater than the velocity of blood exiting through venous line 62. This can be easily achieved with a low pressure dialyzer simply by choosing a larger time course on the dial 86, for example up to a few seconds, and returning the blood more slowly. . The small pressure gradient in the intravenous line 62 due to the low pressure dialyzer ensures that the flow rate returning blood is slower than the flow rate withdrawing blood.

It is observed that the speed of pump 38 should be controlled so as not to draw blood from the patient so quickly as to damage the arterial line or the patient's venous line. However, a faster flow rate that returns blood does not risk damaging the intravenous line or the patient's veins, and a faster flow rate that returns blood is advantageous in maximizing the efficiency of this system. There is.

From the above, it can be seen that improved dialysis of a patient's blood can be obtained using a single venipuncture, with the stroke volume drawing blood from the patient at a relatively slow rate and at a relatively fast rate. It can be seen that this can be increased by injecting blood into the patient. A surprising and advantageous improvement has been demonstrated in this system, namely the significant reduction in blood mixing in the bifurcated connector 28.

The invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The above embodiments are merely illustrative and not limiting of the invention.

[Brief explanation of the drawing]

The drawing is a schematic diagram showing one embodiment of the hemodialysis control device of the present invention. In the drawing, 24 is a cannula, 28 is a connector, 34 is an arterial line, 38 is a blood pump, 60 is a dialyzer, 62 is a venous line, 6
4 is a bubble trap, 66 is a pressure conduction tube, 70 is a controller, and 150 is a clamp.

Claims (1)

Claims: 1. A hemodialysis control device that uses a single cannula 24 to remove blood from a patient via an arterial line 34 and uses the same cannula 24 to return blood to the patient via a venous line 62. a clamping means 150 that alternately opens and closes the arterial line and the venous line; a pump 38 that pumps blood in one direction from the arterial line to the venous line; and the clamping means 150 by electric wires 160, 162. a pressure sensor 84 that is connected to and controls the alternate opening and closing of the arterial line 34 and the venous line 62 and is connectable to a drip chamber 64 disposed on the venous line 62 via a pressure conduction tube 66;
a pressure setting for setting a predetermined pressure applied to the clamping means 150 to generate a first signal that opens the venous line 62 and substantially simultaneously closes the arterial line 34; a hemodialysis control device comprising means 88 and an adjustable timer 86 for generating a second signal after a preset period of time; ping means 150 to open the arterial line 34 and close the venous line 62 substantially simultaneously so that the time it takes to achieve the predetermined pressure is greater than the time setting of the timer 86. , the pressure setting means and the timer 86 are set.