The present invention generally relates to a method and a device designed to, without air or gas admixture, collect and/or convey various types of liquids, to be stored in a closed air free/gas free package or receiver or to be di¬ rectly fed into another liquid system, without any contact with human hands and without any risk of contamination du¬ ring the operation and preferably under sterile conditions.

The invention can be used when handling various types of liquids and for many purposes, particularly when handling liquids, which easily are damaged, oxidized, gelled etc., i.a. due to influence of air or other gases, liquids which tend to foam when handled, liquids which contain not desi¬ rable or harmful particles or impurities, mixed liquids which tend to separate or form layers etc., during or af¬ ter the collection.

The method and the device can be used e.g. when food-stuffs such as milk, cream, oils, fruit drinks, juices etc. are handled, when corrosive or hazardous liquids of various types are handled, when it is important that the liquid will not contact human skin or be discharged into the en¬ vironment or into drains, when oils are handled or liquid mixtures which are mutually insoluble, when blood is handl¬ ed in connection with medical surgical operations, when various types of waste liquors etc. are sucked.

The invention was developed particularly in connection with the handling of blood, and it will in the following text mainly be described in connection with such a hand¬ ling.

Blood is always a liquid in short supply and large amounts of blood are used during blood transfusions, e.g. in con¬ nection with surgical operations. Blood is expensive to col¬ lect, to test as well as to store. There is also a risk of transmission of jaundice, HIV-infection and other diseases

during blood transfusions.

In connection with certain operations the patient may lose large quantities of blood, sometimes as much as several li¬ ters. This blood normally is wasted and the patient has to receive the corresponding amount of blood through transfu¬ sions.

The problem of supplying blood has to some extent been solved in various ways. There are e.g. methods of purify¬ ing and anticoagulation-treating blood, which has been par¬ tially coagulated, but these methods are expensive and time- consuming, and the transfusion product is inferior. Also, autotransfusions are used now, a patient letting his own blood as a blood-donor a few weeks before a planned opera¬ tion, the patient, in case a need arises, having his own blood restored during or subsequent to the operation. How¬ ever, this method needs planning and cannot be appliedwhen emergency operations are needed. Normally, the patient also must be reasonably healthy, when he is a blood-donor, and equipment for possible purification, catalogueing and sto¬ rage of the patient's blood is required. This method has so far only been sparingly used.

Consequently, the basis of the invention, according to the last mentioned aspects of blood treatment, has been the idea of trying to collect and autologously inject in the patient as much as possible of his own blood, which is re¬ moved from his blood vessel system during the operation.

Four main problems arise when doing this:

- When blood is sucked from a wound surface, large amounts of air or another gas or a gas mixture inevitably are sucked jointly with the blood, which results in an air admixture with a strong frothing, which like the contact of the blood with foreign substances and free air contributes to an ini¬ tiation of the mechanisms, which lead to an activation of

the coagulation system of the blood as well as alterations of or in the cells of the blood;

- When blood is stored in some type of storage unit, air or another present gas as well as froth will be dominant in the storage unit, which accelerates the coagulation and be¬ sides prevents a direct return of the blood to the patient, partly due to the air contents itself and partly also due to the fact that the enzyme system and the cells of the blood are activated by the interface between blood and air bubbles;

- The collected material may contain not desirable tissue fragments from the operation wound (clots, muscle, fat, bone etc.) , which activate the enzyme system of the blood; this activation as well as the admixture of not desirable and in this connection dangerous tissue fragments prevent a direct return of the collected blood to the patient; and

- The collected blood may be infected and consequently it will be clearly inapproriate to return the blood in this condition to the patient.

The above-mentioned problems can be solved according to the present invention with a method and a device, by means of which the patient above all is injected with his own blood, which he has bled from his own blood vessel system due to a tissue injury and/or during the operation (auto- logous transfusion) and which blood has been sucked in con¬ nection with the operation, by means of which:

- The blood which disappears during the surgical operation is sucked continuously;

- The sucked blood/air/gas-mixture receives automaticly and in proportion to the amount of sucked blood an admixture of an anticoagulant agent, e.g. a citrate of a type which is active and known per se, of a disinfectant or of any type of blood preserving agent, controlled by a differen¬ tiated pressure in the system;

- The blood/air/gas mixture is caused, in a closed system, to pass a defoaming and separation filter, in which the

blood froth is disintegrated and not desirable particles are separated, whereas the blood is allowed to pass;

- The blood flows into a receiver, in which the blood is allowed to slowly flow downwards along the walls of the re¬ ceiver or along inclined planes mounted in the receiver, whereas air bubbles included in the blood are allowed to escape to the upper part of the receiver;

- The blood is collected in the lower part of the receiver, which in its bottom is provided with a valve, which opens up when a certain amount of blood has been collected in the bottom of the receiver, the blood flowing into a col¬ lecting vessel, said valve closing again when the blood le¬ vel in the lower part of the receiver has been lowered to such an extent, that there may be a risk that air and gas will follow the blood into the collecting vessel; and

- The collection of the blood in the vessel is done enti¬ rely without any admixture of air or any other gas bymeans of a certain negative pressure, which acts on a completely air-void flexible container, and the suction of air from the upper part of the receiver is done by means of a suc¬ tion system with a pressure, which is higher than the pres¬ sure on the flexible collecting container and the pressure on a container for the anticoagulant.

It is common practise, when blood is collected in bottles or flexible bags, to add an anticoagulant, e.g. a citrate, and this usually is done by dosing in advance a certain amount of citrate solution in the blood bag, calculated according to the amount of blood which the bag is to con¬ tain, the citrate being mixed with the introduced blood. The amount of citrate solution ought to be proportionate to the amount of blood. However, the amount of filledblood may vary, and in case a smaller amount of blood is filled in the blood bag than what had been estimated, then the citrate contents in the blood bag would be higher than what is needed.

Also, the citrate admixture ought to be done as quickly as possible subsequent to the blood collection, and this is particularly true, when wasted blood from surgical opera¬ tions etc. is sucked, and suitably it ought not to be de¬ layed, until the filtrated and de-aired blood finally has been collected in the blood bag. In case the blood, in an immediate connection with the sucking, is returned to the patient's own blood system, then the admixture of the cit¬ rate solution and possibly also a disenfectant must also be done in close direct connection with the sucking of the blood.

Thus, according to the invention a dosage of one or several additives to the sucked liquid is done, in the last desc¬ ribed case to blood, in close connection with the sucking place, and preferably in a place before the liquid arrives to the means of filtering and de-airing of the liquid (the blood) . The dosage device for additives is according to the invention designed in such a way, that the same in a simpel way will yield a surprisingly accurate proportionate dosage in relation to the amount of sucked liquid.

This is done by subjecting the dosage device and the suc¬ tion nozzle for the sucking of liquid to negative pressures at different pressure levels, the pressure gradient between these different pressure levels being calculated in such a fashion, that no additive at all will be introduced, when no liquid is present in the suction nozzle and that the amount of dosed additive will be almost completely propor¬ tionate to the amount of sucked liquid.

Characterizing features and advantages of the present in¬ vention will be set forth in the following detailed descrip¬ tion of an embodiment of the invention, which is illustra¬ ted in the accompanying drawings.

In the drawings Fig. 1 shows schematicly and substantially

simplified a device designed to carry out the method ac¬ cording to the invention, shown before the device is used to collect a liquid. Fig. 2 shows the device according to Fig. 1 in operation during the liquid collecting.

The device shown in Fig. 1 comprises 6 main parts, which operate with a certain pre-set pressure gradient, namely a main negative pressure P3 (suction) , which acts on some of the parts, and a certain higher pressure P2 (relatively low¬ er suction action), which acts on other parts of the device, which will be explained in the following text, as well as a third additional higher pressure Pi, which can be the at¬ mospheric pressure and at which the liquid or the liquid/ air/gas mixture is sucked into the device.

The main parts of the device have in Fig. 1 been indicated as blocks with dashed lines, although the parts can be comp¬ letely or partially integrated to a continuous disposable device. The parts are as follows:

1) A suction system with means to obtain negative pressures at two different pressure levels, e.g. a suction source, with a pilot valve and a manometer or pressure gauge, de¬ signed to obtain a negative pressure with a lower pressure level P3 and a higher pressure level P2 and connected to the various parts of the device by means of conduit systems and designed to suck a liquid under an additional higher pressure PI;

2) A suction nozzle designed to suck a liquid at an atmos¬ pheric or normal pressure Pi and which is influenced by said relatively high pressure level P2;

3) A separation and defoaming filter, which is connected to the suction nozzle and which is influenced by the rela¬ tively higher pressure level P2;

4) A device designed to dose one or several types of admix¬ ture agents for the liquid, e.g. antioxidation additives, anticoagulants etc. , which agents are influenced by the lower pressure level P3;

5) A receiver with walls or inclined planes, along which the liquid will flow downwards, and provided with means designed to de-air the liquid and with a bottom valve designed to drain the liquid and influenced by pressure at the higher pressure level P2; and

6) Means designed to recover the filtrated and vented liquid by transferring the liquid directly to another liquid system or a system with one or several collecting vessels, direct¬ ly connected to receiver 5 and influenced by a pressure at lower pressure level P3 as well as provided with means de¬ signed to drain the receiver or receivers.

Suction system 1 comprises a pipe or a hose 7, which is con¬ nected to a suitable negative pressure source P3 (not shown), which can be any conventional or available negative pressure source or which can be an air ejection pump or the like. Conduit 7 is through a first branch conduit 8 connec¬ ted to dosage device 4, through another branch conduit 9 to a certain part of collecting vessel 6 and through a third branch conduit 10 to de-air receiver 5 via a pilot valve 11, which controls the gas flow in this branch conduit and consequently also in receiver 5 to a predetermined extent, i.e. to obtain a higher pressure P2 (suction action lower) in receiver 5 than in those parts which are influenced by pressure P3.

In order to be able to preset and read pressure gradient P2- P3 a manometer or pressure gauge 12 is connected between the conduits having pressures P3 and P2 respectively. In the illustrated case the manometer is a water seal manome¬ ter, the pressure gradient being measured in mm water co¬ lumn, but it can just as well be any type of manometer or water gauge. Pressure gradient P2-P3 is controlled by set¬ ting the pilot valve and is adjusted in such a way, read on the water seal or the manometer, that an automaticly acting bottom valve in receiver 5 normally is closed and opens up only when a certain liquid volume is obtained in the lower

part of receiver 5 and closes before the liquid level in the receiver has decreased so much that a risk exists that air or another gas or a gas mixture will pass the valve. The upper and the lower limits of pressure gradient P2-P3 is a very important factor for the function and the safety of the device. The water seal or a similar device used in¬ stead is a guarantee for a reliable control of pressure gradient P2-P3.

The artisan knows very well that the two different negative pressures P3 and P2 respectively alternatively can be ob¬ tained from two external negative pressure sources for the different pressure levels, pilot valve 11 being left out and pressure P2 of the higher pressure level being propaga¬ ted directly into conduit 10 to venting receiver 5.

Suction nozzle 2 can be any known nozzle, designed to suck a liquid in the open air or in any other gas or in a gas mixture. The nozzle is connected to venting receiver 5 via separation and defoaming filter 3 and acts with pressure P2, possibly reduced to some extent due to the restriction, which may exist in filter 3.

Separation and defoaming filter 3 comprises a closed con¬ tainer 13 with a filter insert 14 mounted therein of a type which is capable of partly filtering particles, tissues etc. from the liquid and partly disintegrating foam by se¬ parating air from blood in the foam, when the liquid pas¬ ses through the filter. Filter insert 14 divides up the con¬ tainer into two parts, an upper container part 15, designed to collect foam and particles and a lower part 16, from which the liquid flows to de-air reciever 5. Suction nozzle 2 leads to upper container part 15, and an outlet or con¬ nection tube 17 from lower container part 16 leads to re¬ ceiver 5. Filter 13 suitably is mounted slightly downward¬ ly inclined towards outlet tube 17. Higher pressure P2 acts in filter 13 and is transmitted via connection tube 17 from

the upper part of receiver 5.

The separation and defoaming filter alternatively can be en¬ closed as an integral interior part of the de-air receiver and can be designed as a downwardly widening filter funnel, through which the liquid is sucked, and a lower funnel, which leads the liquid to the walls of the container or the fil¬ ter can be designed as a filter cylinder, which is mounted concentricly inside the receiver and which is sealingly connected to the receiver's upper and lower parts.

At a certain position between suction nozzle 2 and filter 13 a dosage device 4, or several dosage devices, mutually connected in parallel, is mounted on a higher level than suction nozzle 2 and filter 3 and connected to suction nozzle 2 through a connecting tube 18 with a pilot valve 19, by means of which the flow of dosage medium can be regulated. The dosage device comprises a flexible container or a bag 20, which is enclosed in a rigid casing 21, which via branch conduit 8 is influenced by lower pressure P3. Container 20 can be filled through a conduit 22 with a stop valve 23. The pressure between casing 21 and container 20 is lower than the pressure in suction nozzle 2, and this results in a suction action on the dosage medium, which corresponds to a pressure gradient P2-P3. This suction action prevents dosage medium from flowing from bag 20 into suction nozzle, until the pressure in suction nozzle 2 decreases, and this occurs when a liquid in the form of liquid drops or as a liquid column N (see Fig. 2) enters the nozzle and stops a free entry of air into the nozzle, pressure gradient P2-P3 decreasing so much, that the dosage medium, due to the gra¬ vitation, can flow downwards through hose 18.Consequently, in this situation the dosage medium flows into the suction nozzle and is mixed with liquid. The amount of dosage me¬ dium which is mixed with the liquid is proportionate to the amount of sucked liquid.

Three different situations can be distinguished: Situation 1 The device solely sucks air/gas mixture: Pressures P2 and P3 have been set, the device sucking only an air/gas-mixture through suction nozzle 45. Pressure P2 is higher than P3 and a suction force acts on liquid column N, which is as large as pressure gradient P2-P3. This suc¬ tion force prevents dosage medium from flowing through hose 18 and into suction hose 45. The height of liquid columnN, which corresponds to the distance between the upper point in the container and the level of the point where hose 18 is connected to suction hose 45, is adjusted to the set pressure gradient P2-P3 or vice versa, an equilibrium be¬ ing obtained between pressure gradient P2-P3 and the flow resistance in hose 18 on one side and the gravitation, which strives to let the liquid column in hose 18 flow downwards into hose 45 on the other side.

Situation 2 Liquid and gas/air is sucked through suction hose 45:

In this situation the air flow through suction hose 45 is stopped, since the sucked liquid reduces the passage of the air/gas. Pressure P2 is reduced in this way and approaches pressure P3. P3 is constant and independent of the flow in hose 45. This means that the equilibrium is disrupted and the value of pressure gradient P2-P3 decreases, and the suc¬ tion action upwards on liquid column N in hose 18 decrea¬ ses also, dosage liquid due to the gravitation being able to flow downwards in hose 45 with an amount which is deter¬ mined by the existing not balanced pressure gradient P2'- P3.

Situation 3 The device solely sucks liquid: Only liquid is sucked through suction hose 45 and thus no air/gas flow exists through suction hose 45. P2 will in this case be almost as low as P3 and pressure gradient P2'- P3 approaches zero. In this way a maximum and free flow of dosage liquid through hose 18 and into suction hose 45 is obtained. The flow in hose 18 is counteracted to a larger or lesser extent by the flow resistance in hose 18 and the

setting of pilot valve 19. The flow resistance in hose 18 can be changed manually or by means of some type of auto¬ matic mechanism.

In the embodiment of the invention, in which the device is used to collect blood, the dosage medium can e.g. be a so called citrate solution, which as the artisan knows is used to bind the ionized calcium in the blood and in this way prevent the coagulation of the blood. The dosage medium al¬ so contains a disinfectant. Also, it is possible to mount two or several dosage devices in parallel with each other in order to dose citrate solution as well as the desinfec- tant and possibly other agents. The additive can be a li¬ quid, a gel, a powder etc., provided it can be caused to flow into suction hose 2 and be mixed with the sucked li¬ quid. Thus, the additive can be any agent or a mixture of agents having an active influence on the sucked liquid or designed to facilitate the disintegration of the foam or with any other functions.

The dosage medium can be used for many purposes, e.g. ad¬ ding vitamins to liquid food products, adding emulsifiers to oil/water-mixtures and many other purposes.

De-air receiver 5 comprises a closed container unit 24, in the upper part of which connection tube 17 for the li¬ quid ends and which is provided with a system of inclined planes 25, on which the liquid can slowly flow downwards, the air which is mixed with the liquid having a chance to escape to upper part 26 of unit 24. The inclined plane can be a system of inclined plates or a spiral-shaped track or preferably it is a helical tube or a helically arranged flexible hose having such a dimension that the liquid me¬ rely fills a portion of the cross-section, the air having a chance to escape upwards. Also, it is possible to lead the liquid towards the walls of the receiver and thereby let it flow downwards along the walls, and the receiver can for this purpose of course also be made slightly con-

vergent. In the upper part of the container branch conduit 10 also ends, which constitutes an exhaustion tube for air, which can escape directly outwards through pilot valve 11 and suction hose 7.

In the bottom of receiver 24 there is a valve seat 27, in which a type of valve cone seals, which in the shown embo¬ diment is a displacement valve ball 28. Valve ball 28 is de¬ signed with such a mass and such a lifting force in rela¬ tion partly to the pressure in the evacuation conduit 10 and partly to the pressure from the outlet of the receiver, that it will open up, when a certain amount of liquid co¬ lumn has been collected on the bottom of the receiver and will close, before the liquid column has been drained comp¬ letely. The risk that air will be sucked through the valve seat and into the collecting container or containers 6 will be eliminated in this way.

The bottom valve in the receiver can be a type of manually or automaticly actuated valve. In case the liquid will be directly transferred to another liquid system, e.g. when citrate-treated, filtrated, defoamed or de-aired blood will be directly restored to the patient, the valve can be a manual valve and can be connected to a hose or a con¬ duit 31a, as is shown schematicly in the drawings.

The valve alternatively can be an electrically , pneu a- ticly or hydraulicly actuatable stop valve, which is ope¬ rationally connected to an electric, optical or capacitive level sensor, which is mounted inside or outside the recei¬ ver and which opens up and closes the valve for a certain predetermined high and low respectively liquid level in the receiver.

In the illustrated case the device is designed with two li¬ quid containers 29 and 30, connected in parallel, which are identical and connected to receiver 1 through a drain con-

duit 31, which starts at valve seat 27. Each liquid con¬ tainer contains a flexible bag 32, which is enclosed in a shape-permanent casing 33. Bag 32 is with its upper part directly connected to drain conduit 31 via a branch conduit 34,35 with a stop valve 36,37. The lower part of bag 32 has a drain conduit 38 with a stop valve 39. The shape-perma¬ nent casing 33 is connected to branch conduit 9 via a stop valve 40, which when it is opened up gives the space bet¬ ween casing 33 and bag 32 the lower pressure P3 and there¬ by causes a suction action on the bag and a suction down¬ wards of liquid from reciever 5, when its bottom valve 28 is opened up. Shape-permanent casing 33 has a second tube joint 41 with a stop valve 42 in order to give the space between casing 33 and bag 32 a positive pressure in order to remove all the air from bag 32, which in Fig. 1 is shown in its flat compressed air-void condition, which is the starting point for liquid suction.

Fig. 2 shows the device in Fig. 1 when used to suck a li¬ quid, e.g. blood, through suction nozzle 2. The function is as follows:

Suction hose 7 is connected to a source of negative pres¬ sure P3, which pressure is propagated through branch con¬ duits 8 and 9 to dosage device 4 and to collecting vessel 6 respectively. Via pilot valve 11 a higher pressure P2 is propagated to receiver 5 and via the latter also through separation and defoaming filter 3 to suction nozzle 2, in which a pressure is obtained, which is at least approxi- matively the same as pressure P2.

Valve 36 to the one container bag 32, the left bag in the drawings, is opened up and valve 40 to container casing 33 is opened up, a pressure P3 being obtained between bag 32 and casing 33.

It is assumed that pilot valve 19 to dosage device 4 in

advance has been set in such a way, that low pressure P3 in dosage device 4 prevents dosage liquid from flowing in¬ to conduit 45 between suction nozzle 2 and filter 13, in case the suction nozzle does not contain any liquid. When liquid is sucked into conduit 45 between suction nozzle 1 and filter 3 pressure P2' decreases in this conduit and this results in a decrease in pressure gradient P2'-P3, which approaches 0, dosage agent in a certain amount in proportion to the amount of liquid sucked from suction nozzle 2 flowing downwards through conduit 18 and into suc¬ tion hose 45 and further into filter 13. The device is then ready to be used.

Suction nozzle 2 is lowered towards the liquid to be sucked. The liquid must be influenced by a pressure PI, which is higher than pressures P3 and P2, and generally the liquid is influenced by the atmospheric pressure in the open air. Usually a mixture of air and liquid drops or a continuous liquid column is sucked into nozzle 2. In case nozzle 2 and suction hose 45 contain liquid, the free air stream through the nozzle is stopped and the pressure decreases (the suction action increases) in hose 45 to filter 3, and this means that pressure P2' approaches the value of coun¬ ter pressure P3 on flexible container bag 20, and that do¬ sage agent, e.g. a citrate solution, flows into suction hose 45 and is mixed with the sucked liquid, e.g. blood.

It was surprising to find that the amount of dosed addi¬ tive will be roughly proprotional to the amount of liquid, which is sucked through suction hose 45, and this is true regardless of how large or small the amount of sucked li¬ quid is and how the liquid is mixed with air/gas, with a large amount of air/gas, with a small amount air/gas or possibly with no amount of air/gas. Consequently, it is possible to obtain an accurate dosage of the additive, which dosage can be varied by setting the pilot valve and above all by adjusting pressure gradient P2-P3.

The simplest embodiment of the present invention only comp¬ rises a suction device 2, which is influenced by a certain relatively high pressure P2 (a low suction action) and a dosage device 4, which is influenced by a certain relative¬ ly low pressure P3 (a strong suction action) and comprises a suction nozzle 2 with a suction hose 45, container 20 of dosage device 4 through its connection joint 18 being con¬ nected to suction hose 45 in the way described above, and suction hose 45, as seen in the flow direction downstreams of the point where dosage device 4 is connected, ending directly in a collecting vessel. The most important fea¬ ture of the invention resides in that fact that dosage de¬ vice 4, thanks to the pressure difference between the two negative pressures P2 and P3, i.e. pressure gradient P2- P3, yields an amount of dosage agent to the liquid, which is sucked through suction device 2 , which amount with a surprising accuracy is proportional to the amount of sucked liquid, regardless of how large or small the amount of air or gas is, which is sucked jointly with the liquid. As is mentioned above, the device can be used in a plurality of various technical situations.

The liquid is sucked along into separation and defoaming filter 3, in which tissue particles, e.g. clots, muscle particles, bone particles and fat etc. are separated on the upper side of filter insert 14 and in which simultane¬ ously also a disintegration of blood froth takes place, which maybe has been formed, when the air/gas/liquid mix¬ ture passed through the suction nozzle and hose 45 up to filter 13, whereas the liquid passes through filter insert 14 and flows into the reciever through conduit 17. The li¬ quid is then allowed, due to its own gravitation, slowly flow downwards along the inclined plane(s) 25 or along the walls of the reciever, the air which has come along with the liquid into receiver 5 and the air bubbles which are included in the liquid being allowed to be separated. The air escapes from the upper part 26 of the reciever

through de-air conduit 10, which is influenced by the higher pressure P2 and then out through suction hose 7. Liquid is collected successively in the lower part of the receiver.

When the liquid has reached a certain predetermined volume valve ball 28 is lifted and liquid is sucked through the in¬ fluence of pressure P3 on container bag 32, which pressure is lower than pressure P2 in the receiver, downwards into container bag 32.

When the liquid level in reciever 5 has been lowered to a predetermined level, set in order to prevent a stream of air into drain conduit 31 and container bag 32 or into hose 31a, valve ball 28 closes again, balanced partly by the mass of the ball and partly by pressure gradient P2-P3, and a new unit volume of liquid is collected in the same way on the bottom of the receiver.

In case bag 32 in one of the liquid containers will be full, valves 36 and 40 are closed and the corresponding valves in the other, the shown right-hand liquid container are opened up, this second container being filled with liquid in the same way. Filled liquid bag 32 can be emptied in a handling bag and the liquid be directly fed to the patient, possib¬ ly via a blood processor or to a cold storage device, to be used at a later date. When a so called heart-lung-machine is used, the collected blood can with advantage be direct¬ ly transferred to the vein reservoir of the machine and from this reservoir to the patient. Filled bag 32 in the collecting vessel can be emptied through gravitational flow, but the drainage can also be done by applying a po¬ sitive pressure in the chamber between casing 33 and bag 32 via connection 41.

As is known, a contact with foreign substances such as walls in flow conduits and apparatuses may activate the cells of the blood and its enzyme system, e.g. the coagu-

lation system and the cells of the blood, which will strong¬ ly and harmfully affect the quality of the blood. In order to eliminate these problems when treating blood by means of the described device at least some of the walls in suction nozzle 2, suction hose 45, filter 3, connection tube 17, de-air receiver 24 as well as on inclined planes 25 can be provided with a coating of an agent, which does not affect the liquid, e.g. a resistant heparin, which is capable of inhibiting the mechanisms, which activate the coagulation system of the blood as well as changes of or in the cells of the blood. Several heparinizing methods and similar me¬ thods are known, one of them being protected i.e. by Euro¬ pean patent No. 86.186.

In order to achieve a satisfactory result, when a citrate solution is dosed in blood, the dimensions of connection tube 18 of the citration device, the setting of pilot valve 19 and above all pressure gradient P2-P3 suitably can be selected in such a way, that citrate bag 20 doses an amount of citrate solution, which is equal to 8-20 % of the amount of blood, which flows into suction nozzle 2 and through suction hose 45.

The apparatus shown in figure 3 basically corresponds to the apparatus shown in figures 1 and 2 and those parts of figure 3 which are equivalent to the earlier described apparatus have been given the same reference numeral plus having a prim-index. The latter apparatus structurally differs from the earlier apparatus in that the separation and defoaming filter 3 and the de-airizing receiver are combined to a common unit. In this cas the dosage agent is collected in a funnel formed container on top of the filter 14' in which the substance is mixed with the blood entering through the conduit 45. The blood enters the container 13' tangentially like a cyclone. After the blood has been filtered and defoa ed the blood flows downwards along the walls of the container 13' through several successive

collection pockets 47 having overflow walls 48 before the blood enters the drain conduit 31.

Figure 3 also shows that a valve can preferably be arranged adjacent the end of the suction nozzle 2, since it may happen that fragments get stuck at the point of the suction nozzle so that said nozzle becomes blocked. For preventing dosage agent from thereby being transmitted into the blood mixing part of the apparatus in case no blood is supplied it is important that the suction nozzle may easily be evacuated. The valve of the suction nozzle may for instance, as known, be formed as a finger hols in the nozzle tube as shown in the detail picture of figure 3.

REFERENCE NUMERALS