WO2001014048A1

WO2001014048A1 - Method and apparatus for handling and dosing of an additive while collecting a liquid

Info

Publication number: WO2001014048A1
Application number: PCT/SE2000/001591
Authority: WO
Inventors: Lennart STRÖMBERG
Original assignee: Two Inventors Hb
Priority date: 1999-08-23
Filing date: 2000-08-18
Publication date: 2001-03-01
Also published as: SE9902971L; SE9902971D0; AU6883300A

Abstract

A method and apparatus for mixing fluids comprising aspirating at least one fluid by means of a suction means (B); transporting said fluid through said suction means (B) and a defoaming unit (C) communicating with said suction means (B); defoaming the aspirated fluid in the defoaming unit (B) by virtue of subjecting the fluid to a G-force other than the force of gravity in said defoaming unit to thereby provide a quick and effective elimination of substantially all foam which may be present in the fluid aspirated by the suction means; in situ measuring the flow of said defoamed fluid output from said defoaming unit (C); dosing an additive into the fluid at said output of said defoaming unit (C), from an additive container (27) via a connection conduit (29), in dependence of, preferably proportional to, the measured flow of said fluid; transporting the fluid and the additive through a mixing unit (F) communicating with said defoaming unit; mixing the aspirated fluid with the additive in the mixing unit by virtue of subjecting the fluid and the additive to a G-force other than the force of gravity in said mixing unit to thereby provide a quick and effective mixing of the fluid and the additive; and collecting the fluid and additive mixture using a calm, laminar flow.

Description

METHOD AND APPARATUS FOR HANDLING AND DOSING OF AN ADDITIVE WHILE COLLECTING A LIQUID

TECHNICAL FIELD OF THE INVENTION

The present invention generally relates to a method and an apparatus for precisely, quickly and effectively collecting a fluid, which comprises at least one liquid phase, dosing an additive into said fluid, and mixing said fluid and said additive with one another.

DESCRIPTION OF RELATED ART AND BACKGROUND OF THE INVENTION

The invention is useful for handling of various kinds of liquids and for various purposes, in particular for handling of liquids which may change their properties, e.g., by becoming oxidized, gelatinous, foamed, etc., depending on the influence of the handling and/or of a changed environment. The changed environment can be contact with new materials - solid material, gels, liquid, gas, etc. Consequently, this includes handling of liquids which tend to form foam or froth during the handling thereof, liquids containing non-desired or harmful particles or impurities, mixed liquids which tend to separate or to form layers, etc., during or after the collection thereof.

The method and the apparatus can be used, e.g., for handling of food stuff like milk, cream, oils, syrups, juices, etc. and/or for handling of liquids of various kinds which are corrosive or harmful to the environment. It also may be used at handling liquids when it is important that the liquid does not get in contact with human skin, is let out in nature or is drained before it has been rendered harmless by dosage of an additive. The invention may for instance be used for handling of oils or mixed liquids which do not solve in each other until an appropriate addition has been dosed, in collecting and handling of blood in connection to surgical procedures and treatments, for sucking up waste liquids of various types to render them harmless, etc.

The invention has been developed especially m connection to handling of blood. In the following the invention will mainly be described m connection to such handling. This is, however, no restriction of the invention to the said particular field of use.

There are several medical reasons for giving blood to a patient by transfusion. As an example, at surgical operations blood losses are inevitable. Major blood losses can be fatal if not treated. These blood losses can be compensated by transfusion of blood from human donors (homologous blood transfusion) or by giving the patient his own blood (autologous blood transfusion) , a procedure for which methods exist. Some of these procedures are in clinical use.

In the health services organizations worldwide blood for homologous transfusion has always been and still is m short supply. Considerable amounts are used for transfusions on different indications, e.g., in connection to surgery on humans - as mentioned above - and on animals also. Blood is an expensive product due to the costs for collecting, testing and storing the same and the administration of the precise handling of the same. At homologous blood transfusions there is a risk of transferring detrimental diseases such as hepatitis, HIV infections, and different tropical diseases among others. Furthermore, there might be long-term reactions, the importance of which is not known yet for the medical expertise.

There are surgical interventions when the patient looses large amounts of blood, sometimes several liters. Normally such blood is wasted. It is necessary for the success of surgical treatment that major blood loss is replaced and that the patient will get a corresponding amount of liquid, preferably blood. It should be noticed, however, that in adult losses not exceeding one liter less frequent are replaced by blood transfusion.

Various attempts have been made to solve the problem of the lack of blood and blood components for transfusion in connection to medical treatments, e.g., surgery. Furthermore, a very great deal of work is put in minimizing the risk for transferring diseases, induced long and short-term detrimental consequences at respectively of these procedures. The success has not been 100 per cent proof. Furthermore, the procedures are expensive and manpower demanding.

As an attempt to avoid the risks with homologous blood replacement, a method in practice will be described shortly. Notice that in the said method only a part of the patient's own blood is used at this type of "autologous" transfusion.

During surgery the patient's own blood is sucked up from the surgical wound. The blood is "purified" by a washing technique to that extent that only the red blood cells will remain from the patient's own blood and that will be the part of the patients own blood the patient will get back by transfusion. However, these, the patient's own red blood cells must be suspended in, e.g., physiological sodium solution or in plasma from a donor. The result is that the patient will not be compensated with whole blood but only with one of the blood' s important contents - the red blood cells - and if suspended in plasma from a donor the patient still will be submitted to the risk of detrimental reactions and the transferring of diseases.

Another technique established clinically for autologous transfusions is tapping the patient on his own blood a few times some weeks before planned surgery, whereupon the said patient, upon need, receives his own blood by autologous transfusion during or after surgery. This technique, can be used only at surgery planned well in advanced and that can be performed after a preset period of time from that the patient has received his diagnosis and the surgery has been decided (elective surgery) .

This technique requires an expensive planning, tapping, storing and professional administration. A serious limitation is that the patient must be in a relatively good condition when tapped so the blood loss will not do him too much harm. Consequently, this procedure demands facilities for tapping and storing of the patient's blood; and a precise cataloging and expensive administration of the patient's blood are available. Obviously, the method has its evident limitations and therefore can not be utilized at emergency cases such as trauma the cases, one of the most blood transfusion demanding situations.

Other techniques for autologous blood transfusions comprise collecting the patient's own blood during surgery from his surgical wound for a following re-transfusion of "whole blood".

In this respect there are some major concerns to handle. The blood leaving the vascular bed will get in contact with injured tissues forming the surgical wound's walls. This contact will activate the blood' s coagulation that is a time consuming process.

When blood is sucked through a tubing system from a surgical wound into a blood collector the activation process will continue unless the internal surface of the tubing is blood compatible or until this process is stopped by an anticoagulant as a sodium citrate solution. Furthermore, it can not be avoided that air is also sucked into the system together with the blood. In fact much larger volumes of air are sucked than volumes of blood in the majority of the cases. The result is that almost all blood will pass though the system mixed with air as foam or froth until it has been defoamed.

It is important that the activation process resulting in polymerization or clot formation (coagulation) is stopped as early and complete as possible during that the blood is collected. This can only be achieved if the blood is defoamed and an anticoagulant is added and mixed to the entire blood portion as early as possible during the blood collecting process. It should be noticed that the blood-air interface is not a blood compatible surface.

Beside blood and air the collected material may also contain non-desired tissue fragments from the surgical wound (clots, tissue fragments, fat, bone particles, etc.). These materials will also activate the same coagulation system during the collection process until the said system has been stopped (inactivated) by the added anticoagulant.

There are per-operative blood collecting devices present on the market by which blood is sucked through a nozzle and tubing into a canister containing a fixed amount of pre-deposit anticoagulant, e.g., sodium citrate, that is acidiferous. Consequently, the first portions of blood sucked into the device will get a deteriorating acidity. The acidity will successively decrease when more blood is sucked and has been mixed with the anticoagulant. The collected blood can not be given back to the patient until the said anticoagulant has been diluted and the mixture blood/anticoagulant has reached an acceptable pH value.

Another shortcoming of these devices is that they do not have any defoaming and mixing facilities resulting in that part of the collected blood will not be reached by the anticoagulant and consequently it will coagulate.

In this context it is appropriate to mention the existence of the apparatus used for post-operative wound drainage. The liquid collected with the same is not "whole blood" but a protein abundant liquid, i.e., a wound secretion. The sterility of this liquid can be questioned. W092/13582 and WO95/21014 also describe a method and apparatus to collect whole blood from the patent per-operatively . This method and technique wherein the blood leaking from the injured tissue into the surgical wound is sucked up into the apparatus, most often together with air forming a foam. At an early stage of this collecting process an anticoagulant, e.g., sodium citrate, is added to the blood/air mixture in relation to the amount of blood just sucked into the apparatus.

The blood/air mixture, handled in the closed system, is thereafter brought to pass a defoaming apparatus, in which the blood foam is dissolved; thus the previously added anticoagulant can be mixed with the entire blood portion. When thereafter the blood/anticoagulant mixture leaves the defoaming unit new foam is formed again. This is due to the design of the defoaming/mixing unit. This foam, however, will not appear as viscous due to the effect of the added anticoagulant. When the foam reaches the following filter, it will stay there until it dissolves due to gravity whereupon the said blood will pass through filters and is collected in a canister.

The filters separate off unwanted materials such as blood clots, parts of soft and hard tissues, respectively. By means of an earlier well-known method the filtered blood in the canister can be automatically transferred into an ordinary blood bag and stored without forming any blood/air interface.

Several factors affect the flow resistance in the system. One of them is the viscosity of material passing through the system, in this case the density of or the relationship blood/air, i.e., the foam passing through the system.

There are problems of said method including, e.g., that the precision of anticoagulant adding is dependent on the flow resistance in the suction line of the system. Several other factors but the passing material' s viscosity affect the flow resistance, e.g., the length of the tubing constituting the suction line, with a factor of one and the radius of the same with a factor of four. If any of these two factors is changed or unstable, the precision of the anticoagulant dosing will be unfavorably affected. This will happened if the tubing by mistake is partly or totally squeezed. It will also happen if a water trap is formed in a bend of the tubing.

If the suction line before the site of the anticoagulant adding is totally squeezed or if the flow through the system is accidentally stopped by other reasons it will result in an uncontrolled, not observed inflow of anticoagulant into the suction line that might have unwanted medical consequences.

The risk for creating bends increases with the length of the suction line between the nozzle and the site for the adding the anticoagulant .

To minimize this risk of getting bends on this part of the suction line the length of the said formed by flexible tubing must be kept as short as possible. This means that the apparatus per se must be placed close to the patient and the surgical wound. It will then compete for the limited space close to the patient and the operation table and where it must be placed, interfering with the staff's work.

Furthermore, the precision of the anticoagulant dosage is dependent on the vertical length of the anticoagulant column and length of the column varies with the amount of anticoagulant that has been consumed from the respective bags/containers containing the anticoagulant. Concomitant with that the said liquid is consumed the percentage dosage of anticoagulant is changed in a non-regular fashion. Consequently, the consumption of coagulant will affect the precision of the preset coagulant dosage .

In short, several uncontrollable factors might limit the precision and safety of the anticoagulant dosage.

Another imperfection of the said apparatus is the design of its defoaming/mixing unit. It consists of tubing fixed at two points and passing through a hole that is placed eccentrically in a wheel. When the wheel is rotating the tubing is describing a movement corresponding to that of a skipper's rope the heaviest of the content of the foam - the blood - will be pressed against the tubing wall and the bubbles of the foam burst. In the defoamed blood there will be turbulence that together with the defoaming will created possibilities for a sufficient mixing of blood and anticoagulant. When mounted into the apparatus, the tubing must be treaded through the eccentrically placed hole in the said wheel. This will make it hard to get the tubing through the hole without hazard of compromising the necessary sterility.

Another but probably minor problem when it comes to blood handling with the known defoaming and mixing unit is that it does not operate satisfactorily, as the defoaming will occur again when the centrifugal force is decreasing concomitant with that the blood is passing through the second part of the said unit .

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a method for quick, effective and secure mixing of fluids, each containing at least one liquid phase, with one another, which, compared with the methods mentioned above, is more effective and has a better precision at the same time as it avoids some of the problems discussed above. It is in this respect a particular object of the invention to provide such a method that is accurate, stable, easy to install and maintain, and of low cost.

It is yet a further object of the invention to provide the method in such a way that it is easily reconfigurable to meet changing demands .

These objects among others are, according to one aspect of the invention, fulfilled by a method as claimed in Claim 1.

A further object of the present invention is to provide an apparatus for performing the method according to the first aspect of the invention.

Consequently, there is according to a second aspect of the present invention provided an apparatus as claimed in Claim 18.

Furthermore, there is according to a third aspect of the present invention provided a tubing as claimed in Claim 33.

Finally, there is according to a fourth aspect of the present invention provided an apparatus as claimed in Claim 45.

Further characteristics of the invention and advantages thereof, will be evident from the following detailed description of embodiments of the invention, which are shown in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description of embodiments of the present invention given hereinbelow and the accompanying Figs. 1-4, which are given by way of illustration only, and thus are not limitative of the invention. Fig. 1 illustrates diagrammatically, and in a simple design, an apparatus for sucking up liquid according to an embodiment of the present invention.

Fig. 2 illustrates schematically two different implementations of a defoaming unit and/or mixing unit as part of the present invention.

Fig. 3 illustrates schematically the different parts of the defoaming unit and the mixing unit, respectively, from a functional point of view according to the invention.

Fig. 4 is an example of results from a flow measurement as performed using an optical method constituting an embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

In the following description, for purposes of explanation and not limitation, specific details are set fourth, such as particular hardware, applications, techniques, etc. in order to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known methods, protocols, apparatuses, and circuits are omitted so as not to obscure the description of the present invention with unnecessary details.

The apparatus shown in Fig. 1 operates preferably with a predetermined negative pressure gradient, namely a main partial under-pressure (suction force) acting on certain parts of the apparatus, and a higher pressure which may be a constant external pressure, for instance atmospheric pressure, and at which the liquid or the liquid/air/gas mixture is being sucked up. The apparatus comprises seven main parts, which are connected to form an integral unit. The parts are the following.

A) A suction system having means for creating a partial underpressure of a particular pressure level (i.e., a particular suction force) , and which suction system is connected to the various parts of the apparatus by means of a tube or hose system arranged for sucking up liquid under a higher pressure.

B) A suction means for sucking up liquid at atmospheric pressure or at another pressure.

C) A defoaming unit, which is connected to the suction means B.

D) A measuring and control device for measuring the blood flow through an outlet end of the defoaming unit and for controlling a dosing unit E.

E) Unit for dosing any type of one or more additives to be admixed to the liquid, for instance an anticoagulant, an antioxidant, etc.

F) A mixing unit, which is connected to, and communicates with the defoaming unit C.

G) A recipient in which the collected liquid with the added dosing additive is received, which may be under the underpressure, and which is formed with a bottom valve for draining the liquid.

The present invention is primarily focused on the defoaming unit C, the measuring and control device D, the dosing unit E and the mixing unit F, but all parts will at least be briefly overviewed in the following description. However, the suction system A, the suction means B, and the recipient G may all deviate substantially from the embodiments depicted in detail below. As a matter of fact any suction systems and means, recipients and packing units known in the art may be employed in the present invention.

Suction system A

In the apparatus shown in Fig. 1 the suction system A comprises a suction connection 12 m the form of a tube or a hose which is connected to a suitable source (not shown) of partial pressure P3 which can be any type of conventional or available source for obtaining an appropriate suction force. It may be an air ejector pump or a similar means. The conduit from the suction connection 12 is connected to the recipient G over a conduit 15. The underpressure acting as a suction force for sucking a liquid into the suction means may be arranged to be pulsating or intermittent.

Suction means B

The suction means B comprises a suction nozzle 17 of any known type suited for sucking up a liquid present in the open air or in any other type of gas or gas mixture. The nozzle 17 is connected to and communicates with the collection recipient G over a suction conduit 19, the defoaming unit C and the mixing

Defoaming unit C

The defoaming unit C is intended to provide a decomposition of the foam and a separation of air. The defoaming unit C is formed as a kind of apparatus, which centrifuges the liquid and the foam thereby providing the effective defoaming of the liquid.

In the illustrated case the centrifugation apparatus comprises a flexible hose 20 which, with the two ends 20a, 20c thereof, is kept still standing by two hose holding means 22, 24, and which with an intermediate hose part 20b, is held by a centπfuging means 25, as one out of many possible examples. The inlet end 20a of the defoaming hose 20 forms a receiver for the liquid entering through the suction hose 19. The outlet end 20c of the defoaming hose 20 leads then to and communicates with the mixing unit F.

For obtaining a good function of the apparatus the defoaming hose 20 may have a larger diameter than the suction hose 19.

The defoaming unit C, which may preferably be identical with or similar to the mixing unit F, is shown more in detail, though schematically, in Figs. 2 and 3. The unit comprises a flexible hose 20 which is kept stationary between the two hose holders 22, 24 and of which an intermediate part 20b thereof is held by a bar 25a of the said centrifuging means 25. In the illustrated embodiment the centrifuging means 25 comprises the bar 25a mounted eccentrically at two wheels 25b, 25c, which when rotated by the motor (not shown) transfer their rotating motion into a circular motion of said bar 25a and, consequently, of said hose, as indicated at 25d in Fig. 2. Thus, the hose 20 is formed with a radially outward projecting loop providing a centrifugal zone.

The hose 20 may be mounted at the end of bar 25a as shown to the left of Fig. 2 or along the length of bar 25a as shown to the right of Fig. 2.

The defoaming unit C may further comprise means for attaching and detaching the hose 20 to and from the rest of the defoaming unit C, i.e., to and from bar 25a, without any risk for contamination of said hose 20. This may be implemented as a snap fit of hose 20 to bar 25a, or the like.

Considering Fig. 3, which schematically illustrates the different parts of the defoaming unit (and the mixing unit) from a functional point of view, the hose 20 comprises as already mentioned three sections 20a, 20b, and 20c. The central section 20b is elongated, and has a predetermined length, wherein it is substantially straight, thereby extending the time said fluid is exposed to said G-force. The defoaming unit C may further comprise means for adjusting the speed of rotation of wheels 25b, 25c, i.e., the G-force in the hose 20, to a value which is optimized for the fluid aspirated by the suction means B.

Measuring and control device D

The measuring and control device comprise a sensor 26a connected through connection 2βb to an analyzer/control unit 26c, which in turn is connected through connection 26d to the dosing unit E.

The measuring and control device D is arranged for in situ measurement of the flow of the defoamed fluid through the outlet of the defoaming unit C and for measurement processing and analyzing, and optionally for controlling of the dosing unit E for dosing of an additive into the fluid in dependence of, preferably proportional to, the measured flow of said fluid. The control section may optionally be part of the dosing unit E.

The measuring device is preferably implemented using a non- intrusive, preferably optical, probe. The measuring device may be arranged for measuring the instantaneous amount of fluid and the velocity of said amount, thereby yielding the flow rate of the said fluid.

In the following a particular embodiment of the measuring device according the present invention, wherein the velocity is determined by recording the amount of fluid in windows, located at different positions along the flow direction, at various times, and by correlating the recordings, thereby estimating the velocity, will be described.

Optical measurement of blood flow

An experiment to verify the method was performed. The hose, viewed by the camera, was mounted vertically and a sucking force was obtained using a vacuum cleaner. In front of the camera, which was also mounted vertically, the hose was made flat to achieve a substantially rectangular cross-section of the hose. This was obtained by two black painted plates, which were pressed together. Three 8 mm wide windows (apertures) with 5 mm distance in-between were arranged in these plates. The camera was recording images of the three windows, and storing these on videotape. The blood flow velocity varied between zero and just above 0.5 m/s.

From the video recordings three sequences, each of 18 seconds of flow, were digitized. The video images (with interlace) were divided in their two component images (odd/even) to achieve an actual image frequency of 50 Hz. The divided images had an image scale of approximately 0.1 mm/pixel horizontally and 0.2 mm/pixel vertically. There were 65 pixels across the hose.

The rectangular cross-section having a large distance across the hose in comparison to the depth (seen from the camera) enabled the measurement of the instantaneous amount of fluid in a cross- section to be simplified. Accordingly, the number of fluid- filled resolution elements (pixels) was used as the amount of fluid, given that every fluid-filled element was considered to be completely filled. In practice, the images may be thresholded at a certain appropriate intensity level. The filling ratio may be measured in columns for each measurement window. This was performed for the testing sequences, but the method was developed so that only fluid along the side walls, where substantially all the flow occurs, was measured.

The flow velocity could not be measured directly in each of the three windows in the images. This was due partly to the fact that the blood movement between two images (taken with a period of 1/50 s) sometimes was too large to follow the structures (small bubbles) in one measurement window, and partly to that very few structures were seen in the fluid flow (even after high and bandpass filtering of the images) . Instead, the velocity was determined from the measurements of the filling ratios, which are sensitive to the pulses in the flow. The measurement was performed by correlating the filling ratio signals from the different windows. This method requires that the flow varies intermittently with time, as the correlation is otherwise not possible to perform.

By identifying sections of the measurement series with both visible particles and pulses it could be verified that the pulse velocity is a measure of the flow velocity.

The sensitivity in this flow measurement is dependent on the image frequency and the distance between the measurement of the filling ratios. The distance must be shorter than the lifetime of the pulses but long enough to obtain some sufficiently high accuracy. The image frequency required depends on the flow velocities. If the image frequency is too low the pulses are under-sampled and the correlation becomes unsure.

In the measurement described the distance between the measurement points was 13 mm and the image frequency was 50 Hz. At the double distance the correlation was somewhat deteriorated but it was not possible from the measurement data to draw any conclusions about a maximum distance. The measurement frequency was too low for the fastest pulses. During inspection of the individual images in the sequences it was seen that pulses sometimes moved between two windows (13 mm) in one image frame (1/50 s) . If it is supposed that 13 mm is an appropriate distance, the image frequency should be increased by a factor of 5-10 in order to give as many time steps per distance.

The time window for correlation between the signals is dependent on the frequency of the pulses, which was highly variable. Sometimes there were pulses very close to each other for correlation and then a smaller time window was required. Other times the distance between the pulses was large. In the measurements shown in Fig. 4, a time window of 1.5 s was used. It is also possible to measure the velocity with smaller time windows, but then the velocity must be estimated in areas without pulses.

The number of resolution elements across the hose (giving the filling ratio) was 65. The number required may be deduced from the measurements. The image-to-image variations in areas without clear pulses ought to be a measure of the "noise" in the measurement (the differences in measured filling ratio despite the same real filling ratio) . The root-mean-square variations in a "pulse free" area was measured to be 1.1, which means that the number of resolution elements neither should increase nor decrease.

A conclusion of the measurements performed is that the flow of a fluid may be measured by using a video camera and image processing means, if the hose is made flat, e.g., compressed, and is illuminated from the backside and if the flow occurs intermittently. Optimally, a higher measure frequency than a video camera may perform is required.

The instantaneous amount of fluid in a cross-section is directly obtainable from the image of the hose, while the flow velocity is deduced from the pulses in the flow. It is not possible to determine the flow velocity directly from the structures of the fluid, as they are not very clear. The measuring method is thereby dependent of that the flow occurs intermittently and that it does not completely fill the hose. Otherwise, the results will be poor.

With a flat hose mounted vertically the flow occurred mainly along the sidewalls of the cross-section of the hose, which cross-section was substantially rectangular. Sometimes there were fluid or bubbles left in the middle of the hose, but these did not follow the flow, but traveled much slower. The measuring device is therefore preferably particularly sensitive to the amount of fluid near the sidewalls, and not in the middle of the hose, if the flow does not increase so much that also the middle part is filled.

The accuracy of the method is dependent upon the distance between the measurement windows (that is set by the lifetime of the flow pulses) and the measuring frequency. The time window for the correlation is dependent on the pulse frequency.

With the measuring method chosen, two 1-dimensional measurements are needed with a resolution of 60 pixels across the hose or higher, corresponding to a distance of about 10 mm. The measuring frequency preferably ought to be around 500 Hz. For a continuous velocity measurement of the flow, the time window for correlation ought to be around 1.5 s, if the same pulse frequency as during the experiments is assumed to be normal. This can be obtainable by using high-speed cameras.

Dosing unit E

At a location between the defoaming unit D and the mixing unit F there is arranged a dosing unit E, or several dosing units for one or more dosing agents connected in parallel to each other. The point of injection of the dosing agent into the fluid may be located close to the measurement section, and preferably a small distance downstream of it, e.g. one or a few centimeters.

In the apparatus shown in Fig. 1 the dosing unit E comprises a container 27a for the dosing agent, connected to the outlet of the defoaming unit C or to the inlet of the mixing unit F over a connection conduit 27b via a pump 27c, preferably a servo or computer controlled pump. The container 27a can be filled over a conduit having a stop valve (not shown) .

The amount of dosing additive, which is supplied to the sucked up liquid, is preferably substantially proportional to the amount of liquid, which is introduced through the suction nozzle. The dosing is controlled from said controlling unit of the measuring device D, but it may likewise be controlled within dosing unit E (not shown in the Figure) . The pump is controlled via connection 26d and used for pumping the dosing additive into the fluid.

The mixing of the dosing additive with the aspirated liquid is performed in the mixing unit F, which is to be described in next section.

In case the apparatus is used for collecting blood the dosing additive may for instance be a citrate solution which, as known to the expert in the field, is intended to bind the ionized calcium of the blood thereby preventing any coagulation of the blood. The dosing additive also may contain a disinfectant. It is also possible to provide two or more dosing apparatuses parallel to each other and arranged to dose both a citrate solution and a disinfectant and possibly still further additives. The additive may be a liquid, a gel, a powder, etc. provided that said additive can be brought to flow into the mixing unit F and can be mixed with the liquid which is sucked up. The additive also may be any additive or a mixture of additives having an active and diluting action on the liquid which is sucked up, or which is adapted to facilitate the solving of the foam, or which has another function.

The dosing additive also can be used for many other purposes, for instance for vitaminizing of liquid foodstuffs, for adding emulsifiers to oil/water mixtures and for many other purposes.

Mixing unit F

The mixing unit F is intended to provide a quick and effective admixing of the dosing additive into the liquid which is sucked up through the nozzle 17, even in case part of the liquid has formed a foam body emanating from the amount of air which is irrevocably introduced through the suction nozzle 17 together with the liquid, which is not completely removed in defoaming unit C. The unit F also may be intended, at the same time, to provide further decomposition of the foam and a separation of air. The mixing unit F, which may be identical with or similar to defoaming unit C, is formed as a kind of apparatus which centrifuges the liquid thereby providing the effective admixing of the dosing additive with the liquid.

In the illustrated case the centrifugation apparatus comprises a flexible hose 32 which with the two ends 32a, 32c thereof is kept still standing by two hose holding means 24, 34, and which with an intermediate hose part 32b, is mounted to a centrifuging means 25.

The inlet end 32a of the mixing hose 32 forms a receiver both for the liquid entering through the defoaming unit C and also for the dosing additive entering through the connection conduit 27b. The outlet end 32c of the mixing hose 32 leads to the collection recipient or collection canister G.

The mixing unit F may preferably be mounted slightly inclined m the direction down towards the recipient G.

The mixing unit F is shown more in detail m Fig. 2 and 3, which schematically illustrate two different implementations of mixing unit F (and defoaming unit C) . The unit may be identical to said defoaming unit C and a more detailed description of the units may be found under the section of the defoaming unit C.

However, mixing unit F may be provided with a hose section of a successively increasing diameter in the downstream direction, adjacent the outlet of said mixing unit F, whereby the velocity of the air and fluid is decreased and possible production of foam is reduced. Mixing unit F may further comprise means for independent adjustment of the rotation, and thereby the G-force, to a value which is optimized for the mixing of the dosing additive into the fluid.

Receiver recipient G

The receiver/collection recipient G comprises a closed container unit 35 at the inner of which the outlet end 32c of the hose 32 opens. The container may contain a filter 36 for separating foam which may have been formed when the mixture of liquid and dosing additive is sucked into the container from the mixing unit F, and also a separation filter 37 for separating off particles, bone residuals, eventually existing coagulum etc. A conduit 15 opens in the upper part of the container 35, which conduit 15 acts as an evacuation conduit for air which can leave directly through the suction connection 12.

At the bottom of the recipient 35 there is a tapping tube 38 having a tap valve 39. The bottom valve 39 can be of electrically, pneumatically of hydraulically actuatable type, and it cooperates with an upper electrical, optical or capacital level detector 40 which is mounted inside or outside the recipient, and which may be a photocell, initiating an opening of the bottom valve 39 when the surface of the liquid reaches said level detector 40, and which closes the valve 39 before the liquid at the bottom of the container 35 is completely emptied. This control system may be implemented integrally with analyzer/control unit 26d of measuring and control device D, as indicated in the Figure.

Function of the apparatus

The function of the apparatus is depicted as follows:

The suction connection 12 is connected to a source of partial under-pressure which is communicating with the recipient G and over the said recipient, the mixing unit F and the defoaming unit C, and also with the suction nozzle 17, at which an underpressure substantially equal to the under-pressure in the recipient appears. This under-pressure may be constant or time varying, e.g., intermittent.

As long as only air is introduced through the suction nozzle no additive is supplied, but as soon as liquid enters the suction nozzle 17, passing through suction hose 19, into and through defoaming unit C, it is sensed by sensor 26a, which trigger controlling unit 26c to activate the pump 27c. As a result dosing additive is automatically added m dependence of the sensed flow of fluid output from defoaming unit C. The amount of dosing additive is preferably proportional to the amount of liquid entering the mixing unit F.

The fluid, which has been sucked up, has to pass through defoaming unit C for reducing the foam in order to sense the flow rate appropriately. Depending on the centrifugal force therein the liquid, or the liquid foam, flowing down the defoaming unit F towards the radially outwards directed loop 20a-c is forced radially outwards against the walls of the hose by a successively increased G-force, whereby the liquid foam is subjected to such a heavy G-force that the foam bubbles break and the air leaves the foam. After having passed the radially outwards directed hose loop the G-force successively decreases so that the liquid, at the end 20c of the hose 20, leaves under a relatively calm flow movement to the measurement point at the outlet end of said foaming unit C.

After the dosing of the additive through connection 27b, the fluid in common with the additive is passed to the centrifugal hose 32 of mixing unit F. Depending on the centrifugal force therein the liquid, or the liquid foam, flowing down the mixing and defoaming unit F towards the radially outwards directed loop 32a-c is forced radially outwards against the walls of the hose by a successively increased G-force, whereby the dosed liquid additive is effectively mixed with the liquid which has been sucked up by the nozzle, even so that the dosed additive spreads over the entire wall, and liquid and dosing additive are mixed thoroughly. After having passed the radially outwards directed hose loop the G-force successively decreases so that the liquid mixture, at the end 32c of the hose 32, leaves under a relatively calm flow movement to the collection recipient G. If hose section 32c is provided with an increasing diameter towards the recipient G, the flow velocity is further reduced, and any tendency for new production of foam is prevented.

In the filter 36, 37 of the collection recipient G tissue particles, eventually existing coagulum, muscle particles, bone particles and fat, etc., are removed. The air accompanying the liquid into the recipient hereby has the possibility of leaving through the conduit 15 of the recipient G .

When the liquid has reached a predetermined level in the recipient this is observed by the level indicator 40, which may be a photo cell, and whereby the bottom valve 39 opens. The outflow is also initiated by the gravitation force.

When the liquid in the recipient G has reached a certain low level, calculated for preventing introduction of air in the tapping conduit 38 and further downstream, the valve 39 closes.

Liquid can be collected in a blood bag (not shown in Fig.' 1) or directly transferred to the patient, eventually via a blood processor. Alternatively said blood bag can be moved to a cool storing means for later use. While operating with a so called heart-lung machine the blood can preferably be directly transferred to the vein reservoir of the machine and from there to the patient. Particular concerns when collecting blood

It is known that the contact of blood with foreign materials like the material of the walls of flow passageways and apparatus, like in heart-lung machines, etc., may activate the cells and the enzyme system of the blood, for instance the coagulation system of the blood, and this strongly influences the quality of the blood in a negative direction. For eliminating said problems while handling of blood by means of the described apparatus it is important that at least the walls of the suction nozzle 17, the suction hose 19, the defoaming hose 20 and the mixing hose 32 are made of a blood compatible material which minimizes the activation of the system mentioned above, or are formed with a layer having equivalent properties and which is capable of inhibiting/minimizing the mechanisms which provide the activation of the coagulation system of the blood and which adversely affects the cells of the blood and function thereof. Several methods of providing such layers, etc., are known in the art.

Furthermore, the apparatus for quickly and effectively mixing fluids, each containing at least one liquid phase, with one another, according to the present invention is preferably provided as a console part and a disposable sterile part, the latter part being the part to contact the blood when operating the apparatus. Thus, the console part preferably comprises suction system A (including suction connection 12 and .branch conduit 15), defoaming unit C excluding hose 20, i.e., holding means 22, 24, and centrifuging means 25 including bar 25a, wheels 25b, 25c, and rotating motor (not shown in the Figures), measuring and control device D (including sensor 26a, connection 26b, analyzer/control unit 26c, and connection 26d) , pump 27c in dosing unit E, mixing unit F excluding hose 32, i.e., holding means 24, 34, and its centrifuging means 25 and level detector 40 of recipient part G, and other appropriate control circuitry. The disposable sterile part preferably comprises suction means B (suction nozzle 17 and suction conduit 19) , flexible hose 20 (including its two ends 20a, 20c and intermediate hose part 20b) , flexible hose 32 (including its two ends 32a, 32c and intermediate hose part 32b), and canister G, i.e., closed container unit 35, filters 36, 37 and, optionally, branch conduit 15, and tapping tube 38.

The disposable part, or portions thereof, may preferably be manufactured in a single integral unit, wherein hoses 20 and 32 and, optionally, conduit 19 are constituted by one and the same hose .

The dosing units, i.e., container 27a for containing the dosing agent and connection conduit 27c of dosing unit E may be disposable and may be integral with the disposable part described above. Alternatively, these latter units are used together with a supply system for supplying dosing additive, e.g., through a conduit having a stop valve (not shown).

According to another embodiment, the present invention comprises A method for precisely, quickly and effectively collecting a fluid, which comprises at least one liquid phase, dosing an additive into said fluid, and mixing said fluid and said additive with one another, comprising the steps of aspirating the fluid by means of a suction nozzle (17) located at an inlet end of a suction means (B) ; transporting said fluid through said suction means (B) ; m situ measuring the flow of said substantially defoamed fluid through an outlet end of said suction means (B) by using an optical sensor; dosing an additive into the fluid at said outlet end of sa d suction means (B) , from an additive container (27a) via a connection conduit (27b) communicating with said outlet end of said suction means (B) , in dependence of, preferably substantial proportional to, the measured flow of said fluid; transporting the fluid and the additive through a mixing unit (F) including an inlet end communicating with an outlet end of said suction means; mixing the aspirated fluid with the additive in the mixing unit (F) by virtue of subjecting the fluid and the additive to a G-force other than the force of gravity in said mixing unit to thereby provide a quick and effective mixing, and optionally defoaming, of the fluid and the additive; and collecting the fluid and additive mixture.

Preferably, the measuring of the flow is performed by measure the amount of fluid and the velocity of said amount, whereby the velocity can be measured by recording the amount of fluid in a first and in a second one-dimensional cross section of the hose, located at different positions along the flow direction, at various times, and by correlating the recordings, thereby estimating the velocity. For this purpose, the hose, at the measurement point, may be provided with a substantially rectangular cross section, with the longer side considerably larger than the shorter side.

Furthermore, this embodiment of the present invention is intended to include any characteristics, particularly but not limited to the various aspects of the measurement technique, as described in the present specification.

Besides, an apparatus for performing the method may include any suitable devices or parts that is known in the art or depicted in the present specification.

In summary, a reliable and high-quality method and apparatus is disclosed for collecting a fluid into an appliance, for quick, precise and effective dosing of at least one additive into the fluid, both preferably liquids, for defoaming the fluid, the additive and/or the fluid/additive mixture, for filtering said mixture into a container, and, optionally, for transferring, manually or automatically, said mixture into plastic containers or bags, where it will be stored without any contact with ambient air, ready for use.

The invention with high precision and insensivity to external influences, which enables a long distance between the suction nozzle and the position where the additive is introduced, which is particularly important in connection to the handling of blood during surgical operations as large parts of the apparatus according to the present invention may be located remote from the operation location, and thus not unnecessarily occupy space that other surgical equipment may need.

Furthermore, using a measuring and control device and dosing means of high quality can perform dosing of high accuracy and adopted for the particular application, which ensures high reliability, good quality, and an overall satisfactory performance.

It will be obvious that the invention may be varied in a plurality of ways. Such variations are not to be regarded as a departure from the scope of the invention. All such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the appended claims.

Claims

1. A method for precisely, quickly and effectively collecting a fluid, which comprises at least one liquid phase, dosing an additive into said fluid, and mixing said fluid and said additive with one another, characterized by the steps of:

aspirating the fluid by means of a suction nozzle (17) located at an inlet end of a suction means (B) ;

transporting said fluid through said suction means (B) and a defoaming unit (C) including an inlet end communicating with an outlet end of said suction means (B) ;

defoaming the aspirated fluid in the defoaming unit (C) by virtue of subjecting the fluid to a G-force other than the force of gravity in said defoaming unit (C) to thereby provide a quick and effective reduction of foam which may be present in the fluid aspirated by the suction means;

in situ measuring the flow of said substantially defoamed fluid through an outlet end of said defoaming unit;

dosing an additive into the substantially defoamed fluid from an additive container (27a) via a connection conduit (27b) communicating with said outlet end of said defoaming unit, in dependence of, preferably substantial proportional to-, the measured flow of said fluid;

transporting the fluid and the additive through a mixing unit (F) including an inlet end communicating with an outlet end of said defoaming unit;

mixing the aspirated fluid with the additive in the mixing unit (F) by virtue of subjecting the fluid and the additive to a G- force other than the force of gravity in said mixing unit to thereby provide a quick and effective mixing of the fluid and the additive; and

collecting the fluid and additive mixture.

2. The method as claimed in Claim 1, wherein the aspirating of at least one fluid is performed intermittently.

3. The method as claimed in Claim 1 or 2, wherein the G-force is created in the defoaming unit (C) by flowing the at least one fluid into a hose (20) formed with a radially outwardly directed loop and comprising the step of rotating the hose whereby the fluid is subjected to an increasing G-force while flowing into the radially outwardly directed loop and a decreasing G-force after having passed through said radially outwardly directed loop.

4. The method as claimed in Claim 3, wherein the hose loop is provided with an elongated central section (20b) of a predetermined length, thereby extending the time said fluid is exposed to said G-force.

5. The method as claimed in Claim 3 or 4, further comprising the step of adjusting the G-force in the defoaming unit (C) to a value, which is optimized for the fluid, aspirated by the suction means.

6. The method as claimed in any of Claims 3-5, further comprising the step of attaching and detaching the hose (20) to and from the rest of the defoaming unit (C) without any risk for contamination of the interior surface or any end portion of said hose (20) .

7. The method as claimed in any of Claims 1-6, wherein the measuring of the flow of said defoamed fluid is performed non- intrusively, preferably optically.

8. The method as claimed in Claim 7, wherein the measuring of the flow is performed by measure the amount of fluid and the velocity of said amount.

9. The method as claimed in Claim 8, wherein the velocity is measured by recording the amount of fluid in a first and in a second one-dimensional cross section of the hose, located at different positions along the flow direction, at various times, and by correlating the recordings, thereby estimating the velocity.

10. The method as claimed in Claim 9, wherein the hose, at the measurement point, is provided with a substantially rectangular cross section, with the longer side considerably larger than the shorter side.

11. The method as claimed in any of Claims 1-10, wherein the dosing is performed by pumping the dosing additive by a pump

(27c) , preferably a servo or computer controlled pump, into the fluid.

12. The method as claimed in any of Claims 1-11, wherein the G- force is created in the mixing unit (F) by flowing the at least one fluid and dosing additive into a hose (32) formed with a radially outwardly directed loop and comprising the step of rotating the hose (32) whereby the fluid and dosing additive are subjected to an increasing G-force while flowing into the radially outwardly directed loop and a decreasing G-force- after having passed through said radially outwardly directed loop.

13. The method as claimed in Claim 12, wherein the hose loop of the mixing unit is provided with an elongated central section (32b) of a predetermined length, thereby extending the time said fluid and additive are exposed to said G-force.

14. The method as claimed in Claim 12 or 13, further comprising the step of adjusting the G-force in the mixing unit (F) to a value which is optimized for the at least one fluid aspirated by the suction means.

15. The method as claimed in any of Claims 1-14, further comprising the step of attaching and detaching the hose (32) to and from the rest of the mixing unit (C) without any risk for contamination of the interior surface or the end portion of said hose (32) .

16. The method as claimed in any of Claims 1-15, further comprising the step of passing the fluid and additive in a hose section of successively increasing diameter adjacent the outlet of the mixing unit (F) , thereby decreasing the velocity of the fluid and reducing the production of foam.

17. The method as claimed in any of Claims 1-16, wherein the fluid is blood.

18. An apparatus for precisely, quickly and effectively collecting a fluid, which comprises at least one liquid phase, dosing an additive into said fluid, and mixing said fluid and said additive with one another, in a tubing having an inlet end and an outlet end, characterized in

suction means removably connectable to said tubing and being arranged for aspirating said fluid through said inlet end of said tubing;

a defoaming unit removably attachable to said tubing and being arranged for defoaming the aspirated fluid by virtue of subjecting the fluid to a G-force other than the force of gravity to thereby provide a quick and effective reduction of foam which may be present in the fluid as aspirated;

a measuring device for in situ measurement of the flow of said substantially defoamed fluid through a section of said tubing located downstream of said defoaming unit; a dosing means removably connectable to said section of said tubing and being arranged for dosing of the additive from an additive container (27a) into the fluid in said section of the tubing, in dependence of, preferably substantially proportional to, the measured flow of said fluid; and

a mixing unit removably attachable to said tubing and being arranged for mixing the aspirated and defoamed fluid with the additive by virtue of subjecting the fluid and the additive to a G-force other than the force of gravity to thereby provide a quick and effective mixing of the fluid and the additive.

19. The apparatus as claimed in Claim 18, wherein the suction means is arranged for aspirating the fluid intermittently.

20. The apparatus as claimed m Claim 18 or 19, wherein the defoaming unit is arranged for attachment of a section of said tubing formed with a radially outwardly directed loop and for rotation of that section whereby the fluid is subjected to an increasing G-force while flowing into the radially outwardly directed loop and a decreasing G-force after having passed through said radially outwardly directed loop.

21. The apparatus as claimed in Claim 20, wherein the defoaming unit is arranged for attachment of a section of said tubing formed with a radially outwardly directed loop in such a manner that said loop is arranged with an elongated central portion

(20b) of a predetermined length, whereby the time said fluid is exposed to said G-force is extended.

22. The apparatus as claimed m Claim 20 or 21, further comprising means for adjusting the G-force m the defoaming unit to a value, which is optimized for the fluid, aspirated by the suction means .

23. The apparatus as claimed in any of Claims 20-22, further comprising means for attaching and detaching the tubing to and from the defoaming unit without any risk for contamination of the interior surface or any end portion of said tubing.

24. The apparatus as claimed in any of Claims 18-23, wherein the measuring device is a non-mtrusive, preferably optical, device.

25. The apparatus as claimed in Claim 24, wherein the measuring device is arranged for measuring the amount of fluid and the velocity of said amount.

26. The apparatus as claimed in Claim 25, wherein the measuring device is arranged for measuring the velocity by recording the amount of fluid in a first and m a second one-dimensional cross section of the tubing, located at different positions along the flow direction, at various times, and by correlating the recordings, thereby estimating the velocity.

27. The apparatus as claimed in Claim 26, wherein the measuring device is arranged for measuring the flow at a measurement point of said tubing, at which it is provided with a substantially rectangular cross section, with the longer side considerably larger than the shorter side.

28. The apparatus as claimed in any of Claims 18-27, wherein the dosing means comprises a pump (27c) , preferably a servo or computer controlled pump, for pumping the dosing additive into the fluid.

29. The apparatus as claimed m any of Claims 18-28, wherein the mixing unit (F) is arranged to create the G-force by flowing the at least one fluid and dosing additive into a hose (32) formed with a radially outwardly directed loop and to rotate the hose

(32), whereby the fluid and dosing additive are subjected to an increasing G-force while flowing into the radially outwardly directed loop and a decreasing G-force after having passed through said radially outwardly directed loop.

30. The apparatus as claimed m Claim 29, wherein the mixing unit is arranged for attachment of a section of said tubing formed with a radially outwardly directed loop m such a manner that said loop is arranged with an elongated central portion (20b) of a predetermined length, whereby the time said fluid is exposed to said G-force is extended.

31. The apparatus as claimed in Claim 29 or 30, further comprising means for adjusting the G-force to a value which is optimized for the at least one fluid aspirated by the suction means.

32. The apparatus as claimed in any of Claims 18-31, further comprising means for attaching and detaching the tubing to and from the mixing unit without any risk for contamination of the interior surface or any end portion of said tubing.

33. The apparatus as claimed m any of Claims 18-32, wherein the fluid is blood.

34. A tubing for precisely, quickly and effectively collecting a fluid, which comprises at least one liquid phase, dosing an additive into said fluid, and mixing said fluid and said additive with one another, said tubing having an inlet end and an outlet end, characteri zed in

that said tubing is removably connectable to a suction means for aspirating said fluid through said inlet end;

that said tubing is removably attachable to a defoaming unit for defoaming the aspirated fluid by virtue of subjecting the fluid to a G-force other than the force of gravity to thereby provide a quick and effective reduction of foam which may be present in the fluid as aspirated;

that said tubing is provided with a portion, located downstream of where said tubing is removably attachable to the defoaming unit, arranged for in situ measurement of the flow of said substantially defoamed fluid through a section of said tubing;

that said portion of said tubing is removably connectable to a dosing means for dosing of the additive from an additive container (27a) into the fluid in said section of the tubing, in dependence of, preferably substantially proportional to, the measured flow of said fluid; and

that said tubing is removably attachable to a mixing unit for mixing the aspirated and defoamed fluid with the additive by virtue of subjecting the fluid and the additive to a G-force other than the force of gravity to thereby provide a quick and effective mixing of the fluid and the additive.

35. The tubing as claimed in Claim 34, wherein said tubing which is removably attachable to the defoaming unit, is in this section arranged with a radially outwardly directed loop, whereby this portion is arranged to be rotated by said defoaming unit in order to subject the fluid to an increasing G-force while flowing into the radially outwardly directed loop and a decreasing G-force after having passed through said radially outwardly directed loop.

36. The tubing as claimed in Claim 35, wherein said loop comprises an elongated central portion (20b) of a predetermined length, whereby the time said fluid is exposed to said G-force is extended.

37. The tubing as claimed in any of Claims 34-36, wherein it is attachable to and detachable from the defoaming unit without any risk for contamination of the interior surface or any end portion of said tubing.

38. The tubing as claimed in any of Claims 34-37, wherein it is provided with a substantially rectangular cross section, with the longer side considerably larger than the shorter side, in the portion which is arranged for measurement of the flow of said substantially defoamed fluid.

39. The tubing as claimed in any of Claims 34-38, wherein it is provided with a successively increasing diameter in the downstream direction in a portion, located adjacent to the downstream end of where said tubing is removably attachable to the defoaming unit, whereby the velocity of the fluid is decreased and the production of foam is reduced.

40. The tubing as claimed in any of Claims 34-39, wherein said tubing, is in this section arranged with a radially outwardly directed loop, whereby this portion is arranged to be rotated by said defoaming unit in order to subject the fluid to an increasing G-force while flowing into the radially outwardly directed loop and a decreasing G-force after having passed through said radially outwardly directed loop.

41. The tubing as claimed in Claim 40, wherein said loop, in the section which is removably attachable to the mixing unit, comprises an elongated central portion (20b) of a predetermined length, whereby the time said fluid is exposed to said G-force is extended.

42. The tubing as claimed in any of Claims 34-41, wherein it is attachable to and detachable from the mixing unit without any risk for contamination of the interior surface or any end portion of said tubing.

43. The tubing as claimed in any of Claims 34-42, wherein it is provided with a successively increasing diameter in the downstream direction in a portion, located adjacent to the downstream end of where said tubing is removably attachable to the mixing unit, whereby the velocity of the fluid is decreased and the production of foam is reduced.

44. The tubing as claimed in any of Claims 33-43, wherein the fluid is blood.

45. An apparatus for quickly and effectively mixing fluids, each containing at least one liquid phase, with one another, characteri zed in

a suction means (B) provided with a suction nozzle (17) at an inlet end thereof, for aspirating at least one fluid, said suction means (B) being arranged for transporting of said fluid;

a defoaming unit (C) including an inlet end communicating with an outlet end of said suction means (B) for further transport of said fluid, said defoaming unit (C) being arranged for defoaming the aspirated fluid by virtue of subjecting the fluid to a G- force other than the force of gravity to thereby provide a quick and effective reduction of foam which may be present in the fluid aspirated by the suction means;

a measuring device for in situ measurement of the flow of said substantially defoamed fluid through an outlet end of said defoaming unit;

a dosing means for dosing of an additive into the fluid at said outlet end of said defoaming unit, from an additive container (27a) via a connection conduit (27c) communicating with said outlet end of said defoaming unit, in dependence of, preferably substantially proportional to, the measured flow of said fluid;

a mixing unit (F) including an inlet end communicating with an outlet end of said defoaming unit for transporting the fluid and the additive, said mixing unit (F) being arranged for mixing the aspirated fluid with the additive by virtue of subjecting the fluid and the additive to a G-force other than the force of gravity to thereby provide a quick and effective mixing of the fluid and the additive; and a collecting means for collecting the fluid and additive mixture using a calm, laminar flow.

46. The apparatus as claimed m Claim 45, wherein the suction means (B) is arranged for aspirating the fluid intermittently.

47. The apparatus as claimed in Claim 45 or 46, wherein the defoaming unit (C) is arranged to create the G-force by flowing the at least one fluid into a hose (20) formed with a radially outwardly directed loop and to rotate the hose whereby the fluid is subjected to an increasing G-force while flowing into the radially outwardly directed loop and a decreasing G-force after having passed through said radially outwardly directed loop, said loop being provided with an elongated central section (20b) of a predetermined length, thereby extending the time said fluid is exposed to said G-force.

48. The apparatus as claimed in any of Claims 45-47, wherein the measuring αevice is a non-mtrusive, preferably optical, device, which is arranged for measuring the instantaneous amount of fluid and the velocity of said amount, wherein said velocity is measured by recording the amount of fluid in a first and in a second one-dimensional window, located at different positions along the flow direction, at various times, and by correlating the recordings, thereby estimating the velocity.

49. The apparatus as claimed in any of Claims 45-48, wherein the mixing unit (F) is arranged to create the G-force by flowing the at least one fluid and dosing additive into a hose (32) formed with a radially outwardly directed loop and to rotate the hose

(32) , whereby the fluid and dosing additive are subjected to an increasing G-force while flowing into the radially outwardly directed loop and a decreasing G-force after having passed through said radially outwardly directed loop, said loop provided with an elongated central section (32b) of a