GB2082475A

GB2082475A - Artificial lung device

Info

Publication number: GB2082475A
Application number: GB8126080A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1980-08-28
Filing date: 1981-08-26
Publication date: 1982-03-10
Also published as: JPS6246192B2; JPS5743748A; AU7475481A; FR2489144A1; DE3133498A1

Abstract

An artificial lung device comprises an artificial lung body 6 for contacting blood with oxygen, so that the carbon dioxide contained in the blood is exchanged with oxygen, blood tubing 2, 14, 18 for connecting an animal body 1 with the artificial lung body 6, so that a circulating blood circuit is formed, and means 13 for removing water from the blood in the blood tubing. The means 13 can be a conventional artificial kidney or liver and is connected in parallel (as shown) or in series with the artificial lung body. The use of the artificial lung device of this invention effectively prevents a decrease in the blood concentration of the circulating blood resulting from the collection 10 of diluted blood from an open wound. <IMAGE>

Description

SPECIFICATION Artificial lung device The present invention relates to an artificial lung device which effects lung functions in place of the lungs. More specifically, it relates to an artificial lung device in which a means for removing water from blood containing the same is incorporated into a circulating blood circle, whereby a decrease in the blood concentration is prevented during a surgical operation.

Heretofore, artificial lung devices are necessarily used in, for example, a cardio-tomy operation. As is well-known in the art, artificial lung devices include a bubble type, a film type and a membrane type. These lung devices generally comprise (i) an artificial lung body for contacting blood with oxygen, whereby the carbon dioxide contained in the blood is exchanged with oxygen to obtain blood containing oxygen and (ii) blood tubing for connecting a human body with the artificial lung body, whereby a circulating blood circuit is formed.

The bubble type lungs are those in which oxygen gas is fed into blood in a bloodoxygen mixing tube through an oxygen disperser, whereby the blood and the oxygen bubble are directly contact with each other.

The bubble type lungs have advantages in that the gas exchange capacity is good and the lungs are compact and are disposable.

These lungs generally comprise a blood-oxygen mixing tube, a blood reservoir and a heat exchanger.

The film type lungs are those in which an oxygen gas is directly contacted with blood in, for example, a rotating cylinder provided with rotating discs therein, whereby the gas exchange is effected. These lungs have an advantage in that the loss and damage to the blood is small as compared with the bubble type lung, although the lung volume is large and the maintenance thereof is not easy.

The membrane type lungs are those in which oxygen gas is contacted with blood through a gas permeable membrane through which both oxygen and carbon dioxide are permeable. The membrane can be in the form of laminates, coils or capillaries. These lungs have advantages in that, since oxygen gas and blood are not directly contacted with each other, the problems caused by the direct contact of the blood with the oxygen gas (e.g.

plasma protein denaturation, fatty globule form, hemolysis and the like) can be effectively prevented.

The blood which is fed into the blood tubing is venous blood and blood bled from an open wound, whereas the blood which is discharged from the blood tubing into a human body is arterial blood.

In the case where a surgical operation, for example, a cardio-tomy operation is conducted by connecting the above mentioned artificial lung device with a human body, the blood bled from the open wound is usually flown into the blood tubing as a diluted mixture thereof being cooled in a mixture of crushed ice water used for cooling cardiac muscles. As a result, the concentration (i.e.

hematocrit value) of blood which is circulated to a patient is undesirably increased with the lapse of time. Therefore, a portion of the circulating blood is withdrawn from the circulating system and, instead, stored blood is supplied to the circulating blood circuit. However, the dilution of the blood is still inevitable. For this reason, a diuretic is administered over 24 through 48 hours after the operation, whereby micturition is accelerated.

However, the use of the above mentioned conventional artificial lung devices undesirably requires a large amount of stored blood. Furthermore, there is a disadvantage in the conventional artificial lung devices that the potassium concentration of the circulating blood is likely to increase due to the presence of a relatively high concentration of potassium in the stored blood. The elimination of these disadvantages has heretofore been strongly desired.

According to the present invention, water contained in the circulating blood is removed from the blood in the circulating blood circuit, whereby the decrease in the blood concentration is effectively prevented and the amount of stored blood to be supplied can be greatly decreased or no substantial amount of stored blood is required to be supplied.

In accordance with the present invention, there is provided an artificial lung device comprising: (i) and artificial lung body for contacting blood with oxygen to exchange carbon dioxide contained in the blood with oxygen; (ii) blood tubing for connecting an animal body with the artificial lung body to form a circulating blood circuit; (iii) means for removing water from blood in the blood tubing, said means being connected in series or in parallel with the artificial lung body.

The present invention will be better understood from the description set forth below with reference to Fig. 1 of the accompanying drawings, in which one typical example of the artificial lung device according to the present invention is illustrated.

The means for removing water from the blood used in the present invention includes those which can selectively remove water, or water and other components having a relatively low molecular weight, from the blood containing the same. Typical examples of such means which can be desirably used in the present invention are, for example, artificial organs such as artificial kidneys, artificial livers and the like, which are heretofore wellknown in the art. These artificial organs clinically provide a lot of actual and satisfactory results and artificial devices having high reliability are reasily available. These artificial organs include dialysis type and ultrafiltration type and are classified as hollow tube type, coil type and plate type, depending upon the shape of the semipermeable membrane used.

The semipermeable membranes used in the above mentioned artificial organs are made from various polymer substances such as cellulose, polyacrylonitrile, polycarbonate, poly(methyl methacrylate), polyethylene, polypropylene and the like.

The above mentioned various types of artificial organ devices can be used, as a means for removing water from blood in the present invention. However, the use of the ultrafiltration type is desirable from the point of view of high throughput capacity and the use of the hollow fiber type semipermeable membrane is desirable in the practice of the present invention.

In order to selectively remove water and low molecular weight substances from the blood, semipermeable membranes through which high molecular weight substances such as blood cell components, protein and the like cannot be removed and through which only low molecular weight components can be removed may be used. For instance, conventional artificial kidneys are usually designed, so that low molecular weight substances having a molecular weight less than the range of 3000 through 10000 can be selectively filtered or dialysed. Therefore, water and other low molecular weight substances such as potassium, sodium and the like contained in the blood can be effectively removed from the blood by the use of the conventional artificial kidneys.

On the other hand, in the case of, for example, a cardio-tomy operation, a relatively large amount of blood cells is damaged by an artificial lung. Especially, the liberation of hemoglobin due to the hemolysis of erythrocyte becomes a problem. The liberated hemoglobin is circulated, together with the other blood components, through the circulating blood circuit. The molecular weight of the liberated hemoglobin is about 34000. Therefore, in the case where a semipermeable membrane through which substances having a molecular weight of about 40,000 or less can be filtered is used in the water removal means, the liberated hemoglobin is preferably removed from the circulating blood system, simultaneously.with water. Those semipermeable membranes through which substances having a molecular weight of about 40,000 or less can be filtered include, for example, polyacrylonitrile type membranes.

The water removal means used in the present invention can be placed in any position of the circulating blood circuit of the artificial lung device. Alternatively, a portion of the circulating blood can be by-passed from the circulating blood tubing and pass through the water removal means. Generally speaking, since artificial materials are likely to cause the hemolysis of blood more or less, the amount of the blood which is contacted with the artificial materials is desirably as small as possible due to the fact that the amount of the hemolysis of blood is decreased. According to the preferred embodiment of the present invention, the preferred amount of the by-passed blood is 5 through 50% by weight, more preferably 5 through 20% by weight, based on the total amount of the circulating blood.The amount of the hemolysis decreases, accordingly, in proportion to the amount of the by-passed blood.

Fig. 1 is a flow sheet in which a typical example of the artificial lung device according to the present invention is illustrated.

Referring to Fig. 1, venous blood from a patient 1 flows, through a line 2, to a reservoir tank 3 in which the venous blood is degassed. Thereafter, the degassed venous blood is introduced through a heat exchanger 5 to an artificial lung 6 by a blood pump 4.

The blood is contacted with oxygen (02) in the artificial lung 6, whereby carbon dioxide (CO2) contained in the blood is released in a gas phase and oxygen is contained in the blood.

The blood is then introduced into a reservoir tank 7. In the reservoir tank, contaminant gases contained in the blood are separated and removed from the blood and, then, the blood is returned to the arteria of the patient, through a blood pump 8 and a filter 9.

Blood bled from an open wound during a surgical operation is introduced, through a line 10, a filter 11 and a blood pump 12, to the reservoir tank 3.

A portion of the blood is by-passed from a line 14, through a pump 15. to a water removal means 13 in which water and other low molecular weight components such as potassium and sodium contained in the blood are removed from the blood. The water and the other low molecular weight components removed from the blood are taken out of the system through a line 16. The resultant blood is introduced, through a line 17, to the reservoir tank 7, in which the blood is degassed, together with the blood from the artificial lung 6, and is returned to the patient 1.

In the flow sheet of Fig. 1, a circulating blood circuit is from lines 2 and 10, through the reservoir tank 3, the heat exchanger 5, the water removal means 6, the reservoir tank 7, the filter 9 and the line 18, to the patient 1. Among the elements contained in this circulating blood circuit, the reservoir tanks 3 and 7 have functions to temporarily reserve the blood and also to degas the blood and the filters 9 and 11 have a function to remove the contaminants contained in the blood from the blood. The blood pumps 4, 8 , 12 and 15 are used for pumping up the blood flow and the heat exchanger 5 is used for cooling or heating the blood flow.A line 19, which is connected to the top of the reservoir tank 3, can be used for feeding various additives, suph as, physiologic saline solution for priming the blood circuit, stored blood, various chemical or physiological agents, nutritive agents and the like, to the circulating blood circuit.

The water removal means 13 used in the present invention can be preferably placed or installed in any line between the reservoir tank 3 and the reservoir tank 7 or a by-pass line of the lines of the circuit between the reservoir tanks 3 and 7 or the elements placed in said lines. The water removal means 13 is desirably placed in the upstream side of the reservoir tank 7 due to the fact that the installation of the degassing means (i.e. the reservoir tank) near the final line (i.e. line 18) ia desirable. In the embodiment shown in Fig.

1, the blood treated in the water removal means 13 is returned to the reservoir tank 7, in which the treated blood is thoroughly mixed with the non-treated remaining blood.

The present invention is further illustrated by, but is no means limited to, the following example, in which a cardio-tomy operation is carried out by using the artificial lung device according to the present invention.

Example An artificial lung device similar to that shown in the flow sheet of Fig. 1 was employed. The artificial lung used was a cellular type artificial lung (Type S-100A available from Shiley, U.S.A.), in which a gas-liquid mixing section and a reservoir tank are combined with each other. The maximum permissible blood flow rate was 6 liter/min. The water removal means used was a cylindrical type ultrafiltration device (Type PAN-15, available from ASAHI MEDICAL CO. LTD, JAPAN) in which a bundle of 11,000 polyacrylonitrile hollow fibers, each having an inner diameter of 200 microns and a membrane thickness of 50 microns was fitted in a cylindrical container made of acrylonitrile-styrene copolymer and having a size of 238 mm X 48 mum+.

Both ends of the bundle were liquid-sealed with a polyurethane resin adhesive. The effective membrane area was 1 1 m2.

First, 1600 ml of stored blood and 1000 ml of GIK solution (i.e. glucose, insulin and potassium solution) (total liquid volume 2600 ml) were filled in to the artificial lung device and, then, the circulating blood circuit was connected to a patient. The operation time was about 100 minutes and the average flow rate of the circulated blood in the circulating blood circuit during the operation was 4700 ml/min. The flow rate of the by-passed blood which was fed to the water removal means 1 3 from the line 14 by the pump 15 was between 190 and 200 ml/min. and the amount of the water removed from the blood in the blood removal means was 21 20 ml in which 7#O milliequivalent of potassium and 262 9 milliequivalent of sodium were included.

On the other hand, 2000 ml of GIK solution and other necessary auxiliary agents were supplied from the reservoir tank 3 during the operation. The hematocrit value of the blood in the circulating blood circuit was, on average, 30% and the potassium and sodium content therein were 3.3 milliequivalent/liter and 124 milliequivalent/liter, respectively.

During the operation, the withdrawal of the blood in the circulating blood circuit was not required and no substantial amount of stored blood was added.

In a case where no water removal means is installed in the circulating blood circuit, the hematocrit value would be greatly decreased to 23 5 % (calculated value) and the blood cell concentration of the circulating blood would be diluted to 21'5%. Furthermore, the potassium and sodium contents of the blood in the circulating blood circuit including a human body would be increased by 7'0 milli-equivalent and 262 9 milliequivalent, respectively.

These are not desirable due to the fact that the load on the kidneys of the patient during the operation is undesirably increased, which is likely to cause malfunction of the kidneys and other disorders.

In order to prevent the dilution of the circulating blood and to maintain the hematocrit level of the blood similar to that of the present invention, a portion of the circulating blood must be taken out of the system and about 4000 ml or more of stored blood must be supplied to the circulating blood circuit.

However, in this case, an undesirable increase in the potassium content of the circulating blood is inevitable.

Claims

1. An artificial lung device comprising: (i) an artificial lung body for contacting blood with oxygen to exchange carbon dioxide contained in the blood with oxygen; (ii) blood tubing for connecting an animal body with the artificial lung body to form a circulating blood circuit; (iii) means for removing water from blood in the blood tubing, said means being connected in series or in parallel with the artificial lung body.

2. An artificial lung device as claimed in claim 1, wherein said means for removing water is an artificial organ in which a semipermeable membrane is used.

3. An artificial lung device as claimed in claim 2, wherein said semipermeable membrane is capable of filtering substances having a a molecular weight of 40,000 or less.

4. An artificial lung device as claimed in claim 1 substantially as described herein with reference to the accompanying drawing.

5. An artificial lung device as claimed in claim 1 substantially as described in the Example.