WO2005032621A1

WO2005032621A1 - Hameoperfusion apparatus for use during cardiac and/or vascular operative procedures

Info

Publication number: WO2005032621A1
Application number: PCT/IT2003/000601
Authority: WO
Inventors: Marcello Mestriner; Angelo Fiorucci
Original assignee: Arcamedica S.R.L.
Priority date: 2003-10-07
Filing date: 2003-10-07
Publication date: 2005-04-14
Also published as: AU2003279527A1

Abstract

The present invention relates to haemoperfusion apparatus for use during cardiac and/or vascular operative procedures and for cardiac and/or respiratory assistance and comprising pumping means (6), a reservoir (4) for the storage of the venous blood, an oxygenator (7) for oxygenating the venous blood, the pumping means (6) being able to draw the venous blood from a patient (3) through a receiving line (2) so as to store it in the reservoir (4) and being able to supply the blood stored in the reservoir (4) to the patient (3) through a return line (1), after the blood has been oxygenated by the oxygenator; the apparatus has the characteristic that it comprises blood shut-off means (14) configured for providing, alternatively, a flow connection between the receiving line (2) and the reservoir (4) or a flow connection between the receiving line (2) and the pumping means (6).

Description

HAMEOPERFUSION APPARATUS FOR USE DURING CARDIAC AND/OR VASCULAR OPERATIVE PROCEDURES

DESCRIPTION

The present invention relates to haemoperfusion apparatus for use during cardiac and/or vascular operative procedures or cardiac and/or respiratory assistance procedures which require the use of extracorporeal circulation, in particular, to apparatus for providing a cardiopulmonary bypass (CPB) or a venovenous bypass according to the preamble to Claim 1.

It is known that a cardiopulmonary bypass enables the gas- exchange function of the lungs and the pumping function of the heart to be replaced temporarily, permitting the treatment of all cases of serious cardiorespiratory insufficiency which cannot be treated by normal treatments such as, for example, extracorporeal membrane oxygenation (ECMO) ; it is also known that a venovenous bypass with an oxygenator (ECC0₂ -extracorporeal C0₂ removal) permits treatment of the serious forms of respiratory insufficiency which are also known as adult respiratory distress syndrome (ARDS) .

A cardiopulmonary bypass is also used in all heart surgery operations in which it is necessary wholly or partially to replace the heart and lung functions .

The cardiopulmonary bypass is thus based on two postulations : 1) the blood circulation can be sustained by mechanical pumps whilst the heart is stopped;

2) the venous blood can be oxygenated artificially in a gas- exchanger when the blood circulation is excluded from the lungs .

These two postulations, which have been studied and tested by researchers over the years, have subsequently been developed and transformed into apparatus which permits effective haemoperfusion during the above-mentioned procedures .

Amongst the various apparatuses that have been developed, so-called extracorporeal circulation apparatus with reservoir and apparatus which does not provide for the use of a reservoir are particularly worthy of mention.

The former are generally used for cardiovascular surgical operations which require the aid of extracorporeal circulation and the temporary replacement of the heart and lung functions (CPB) ; the latter are generally used for cardiac and/or pulmonary assistance procedures (ECMO-

ECC0₂R) .

The reservoir may be of two types : a rigid reservoir or a collapsible bag (a soft reservoir) .

Figure 1 shows cardiopulmonary bypass (CPB) apparatus according to the prior art, provided with a reservoir which may be either of the rigid or of the collapsible type.

In fact, Figure, 1 is a schematic representation of a cardiopulmonary bypass circuit 1 in which a tube 2 is inserted by means of cannulae (not shown in the drawing) , which are generally placed in the right atrium, in the venae cavae, or in the femoral vein, in order to obtain the venous blood from the vascular system of a patient 3. The tube 2 is connected, for example, to a venous reservoir 4 provided with a defoaming -filter 11.

The blood is drawn from the venous reservoir 4 through a tube 5 by means of a pump 6 and is supplied to an oxygenator 7 where oxygen is supplied to the blood and at the same time carbon dioxide is removed therefrom; the blood is then sent to an arterial filter 9 through a tube 8.

Finally, the blood is resupplied to the patient 3 through a further arterial cannula (not shown in the drawing) via a tube 10.

It is known that the venous blood which, in this case, is assumed to come from the venae cavae of the patient 3, may contain air; this air must be completely eliminated before the blood is pumped back into the artery of the patient 3. If this were not done, the air in the blood might give rise to an aeroembolism or, with the use of a centrifugal pump, to blockage of the flow delivered by the pump.

In fact, an aeroembolism occurs when a quantity of air which has entered the extracorporeal circuit re-enters the circulatory system of the patient 3 with the blood.

The entry of air into the extracorporeal circulation apparatus may take place at various levels and may be caused by many factors, amongst which is unexpected emptying of the reservoir 4 due to an alteration in the ratio between the venous drainage flow and the return flow to the patient 3 delivered by the pump 6, a defect in the connection between the venous cannula and the anatomical structures where it is inserted and, more rarely, by a breakage of the components which make up the apparatus described, etc.

These incidents occur, above all, in the venous portion of the apparatus which is disposed between the patient and the reservoir since a suction pressure acts on this portion; this suction pressure may be exerted by a gravitational drainage system, by the connection of the reservoir to a vacuum source (VAVD - vacuum assisted venous drainage) , or by a centrifugal pump (KAVD - kinetics assisted venous drainage) .

The above-mentioned suction systems cause the blood to flow from the patient towards the reservoir 4.

However, by virtue of the presence of the reservoir 4, the air which is dispersed in the venous blood enters the reservoir 4 and leaves the blood and the reservoir either by decanting, if the reservoir is of the rigid type, or by being drawn off by an operator, either manually or by means of a pump, if the reservoir is of the collapsible type, so that the pump 6 supplies air-free blood to the heart of the patient 3, with the advantages that can readily be inferred.

However, an arrangement such as that shown in Figure 1 has some disadvantages, amongst which is the trauma to which the blood is subjected when it passes, upstream, through the defoaming filter 11 if it is present and, downstream, through the arterial filter 9, as well as the fact that the blood which is stored in the reservoir 4 (if a rigid reservoir is used) comes into contact with the air, stimulating an inflammatory reaction in the patient.

With regard specifically to the use of the filters 9 and 11, each of which is generally constituted by a porous septum having pores of dimensions comparable with the dimensions of the substances that are present in the blood flow, when the blood flows through the pores, the suction by the pump 6 causes the substances to undergo lesions which activate an inflammatory and coagulative reaction that may give rise to more complicated postoperative progress for the patient .

It can thus be seen that apparatus of this type has the great advantage of ensuring an absence of air bubbles in the blood but has more than one disadvantage, particularly from the point of view of minimally invasive treatment .

It should be noted that the pump 6 may be of the centrifugal type which is considered less traumatic for the blood, or of the "roller" type.

In both cases, the pump 6 is in any case associated with further pumps (not shown in the drawings) with ancillary functions such as, for example, suction of the blood from the operative area, or infusion of cardioplegic solutions, etc .

Figure 2 shows a diagram of a circuit without a venous reservoir.

In this circuit 12 , the venous blood is drawn out directly by the same pump 6 (centrifugal) which serves to force it into the patient 3 once it has been arterialized by the oxygenator 7 disposed in the line 8.

The advantage of this type of circuit over that shown in Figure 1 is represented by the lesser traumas that are induced in the blood by virtue of reduced contact of the blood with foreign materials and hence a consequent lesser stimulation of the inflammatory reaction which is responsible for more complicated postoperative progress.

The disadvantages of this solution are connected with the absence of the reservoir so that the mass of blood present in the patient cannot be regulated and, more seriously, any air coming from the venous line cannot be eliminated before it reaches the pump.

For this reason, up to now, circuits without reservoirs have been reserved for cardiac and/or respiratory assistance procedures as well as pre-surgical or post-surgical procedures since, in these procedures, in contrast with cardiosurgical operations, the risk of air entering the venous line is minimal and there is no need to regulate the volume of blood circulating by the addition of blood to the reservoir or its removal therefrom.

Recently, with a view to reducing the damage caused by conventional systems, extracorporeal circulation apparatus without reservoirs has also been introduced for cardiovascular surgical operations, as shown in Figure 3, which shows apparatus 12A in which the same reference numerals have been attributed to elements already described, and which draws in the blood and supplies it through the filter 9 by means of the pump 6, without the aid of the reservoir 4.

The apparatus 12A thus has the enormous advantage of inducing less trauma in the blood so as to achieve faster and less debilitating postoperative progress but, at the same time, as already described, has the potential, which cannot be ignored, to supply air to the patient through the arterial cannula, once the air has entered the apparatus. Moreover, apparatus of this type also has the considerable disadvantage of continual interruptions of the flow delivered by the pump; these interruptions are necessary to enable the air to be removed from the apparatus .

In view of the prior art described, the object of the present invention is to provide haemoperfusion apparatus which is free of the defects discussed above with reference to known apparatus.

According to the present invention, this object is achieved by means of haemoperfusion apparatus as claimed in the characterizing part of Claim 1.

By virtue of the present invention, it is possible to combine the advantages of reservoir-free circulation apparatus with the good qualities of apparatus having a reservoir .

The characteristics and the advantages of the present invention will become clear form the following detailed description of several practical embodiments which are shown by way of non-limiting example in the appended drawings, in which:

Figure 1 shows a diagram of blood-circulation apparatus according to the prior art,

Figure 2 shows another diagram of blood circulation apparatus according to the prior art,

Figure 3 shows another diagram of blood-circulation apparatus according to the prior art, Figure 4 shows a first embodiment of apparatus for the circulation and recovery of blood according to the present invention,

Figure 5 shows a second embodiment of apparatus for the circulation and recovery of blood according to the present invention, and

Figure 6 shows a third embodiment of apparatus for the circulation and recovery of blood according to the present invention.

Figure 4 shows a first embodiment of the present invention and the same reference numerals are attributed to elements that have already been described.

In particular, Figure 4 shows extracorporeal circulation apparatus 13 provided with a plurality of flow shut-off means 14 which can select at least two separate tubing paths 15 and 16 alternatively and/or in parallel.

The flow shut-off means 14 are, for example, valve means 17, 18 and 19 each having a valve body 20, that is, a casing in which the orifices for the passage of the blood flow are formed, a closure member 21, that is, a means by which the flow passage is obstructed, and an operating wheel 22 which is operated by means of a rod.

In the specific embodiment, it will also be noted that the path 15 is constituted by a first portion 15A which can ensure a flow connection between the valve 17 and the reservoir 4 and a second portion 15B which can ensure a flow connection between the second valve 18 and the pump 6, and the path 16 is constituted by portions 16A and 16B which can ensure a flow connection between the valve 19 and the pump 6.

The valve means 17, 18 and 19 are, for example, straight two-way valves, that is, valves having the flow inlet and outlet on the same axis, but the use of right-angled two-way valves, that is, valves having perpendicular flow inlet and outlet may also be considered.

More specifically, the valves 17, 18 and 19 may be of the on-off type or of the regulation type, the former being fitted with the purpose of excluding portions of tubing, for example, 15 or 16, when they are not in operation, and being usable in the fully open or fully closed position, whereas the latter permit gradual and measured variation of the flow, that is, a very precise flow-rate corresponds to every degree of opening.

Now, upon the assumption that the state of the valves 17-19 is that described by Table 1 below:

Table 1

the venous blood flow taken from the vena cava of the patient 3 flows through the tube 2, and through the defoaming filter 11 to reach the valve 18 which allows it to flow solely through the tube 15A and from there to the venous reservoir 4. It should be noted that this defoaming filter 11, as already stated, is a device which can be produced either in integrated form with the reservoir 4, or separately therefrom.

The blood is then drawn from the venous reservoir 4 through the tube 15B by means of the pump 6, by virtue of the open state of the valve 18. The blood is then passed through the oxygenator 7, by means of the tube 8, to the arterial filter 9 (optional device) and finally to the patient 3 through the arterial cannula, via the tube 10.

Now, upon the assumption that the state of the valves 17-19 is that described by Table 2 below:

Table 2

the venous blood flows directly from the defoaming filter 11 to the pump 6 and is then supplied through the oxygenator 7 to the patient 3.

The advantage achieved by an embodiment of this type can easily be seen. In fact, it is possible to change from a situation in which there is disconnection of the blood flow between input and output from the patient to a situation of equilibrium of the flow exchanged, simply by the combination of the states of opening and/or closure of the valves 17, 18 and 19. Haemoperfusion apparatus for extracorporeal circulation is thus obtained which can ensure the minimum of traumas to the blood and less debilitating postoperative progress and, above all, which can ensure that it is impossible for air to be supplied to the patient.

In fact, initially, a technician operating apparatus of this type (also known as a perfusionist) can set the haemoperfusion apparatus in accordance . with Table 1, thus preventing cases of aeroembolism and, once the situation has stabilized, can change to the haemoperfusion apparatus according to Table 2 , thus producing fewer lesions in the blood.

With particular ..reference now to Figure. 5, this shows extracorporeal circulation apparatus 24 according to a second embodiment in which elements already described are attributed the same reference numerals and which uses valve means 25 and 26 as flow shut-off means 14.

In particular, the valve means 25 and 26 are three-way valves, that is, -valves having two possible inlets and one outlet or vice versa .

As can be seen from the diagram of Figure 5, upon the assumption that the valves 25 and 26 have respective operating states in which the tubing 15 is active, that is, in which the blood flow passes through the venous reservoir 4 with which the defoaming filter 11 is incorporated, through the valve 26, and in which the portion of tubing 16 is excluded from the apparatus, the blood flow is supplied to the heart of the patient 3 by passing through the venous reservoir 4. Conversely, if the portion 15 is excluded, the blood is supplied to the patient 3 directly by the pump 6, through the tubing 16.

In other words, the two embodiments just described achieve the object of not inducing traumas in the blood withdrawn and, above all, enable the technician using the above- described apparatus 13 and 24 to prevent air bubbles circulating in the body of the patient 3.

With reference now to Figure 6, in which a further embodiment of the present invention is shown and elements already described are attributed the same reference numerals, this shows a section through a reservoir 27 which is in input flow communication with the tube 15A and in output flow communication with the tube 15B.

This reservoir 27 is a possible embodiment of the reservoir 4 of the embodiments shown in Figures 4 and 5.

As can be seen from Figure 6, the shut-off means 14 and their flow connee-tion 16A are contained entirely inside the reservoir 27.

The different states of activity of the shut-off means 14 are brought about by means of a control member 28 which is positioned, for example, on the outer surface 27a of the reservoir 27.

The operation of the shut-off means 14 in this embodiment is identical to that described with reference to Figure 5.

The control member 28 may be, for example, a button which can be pressed by the operator so as to modify the states of activity of the shut-off means 14 simultaneously. In the specific embodiment, the shut-off means 14 are three- way valves the respective operating wheels of which are operated mechanically, by means of known kinematic mechanisms, as a result of the operation of the control button 28.

In the embodiments described, the valves 17, 18, 19, 25 and 26 may be operated manually, by means of compressed air, or by means of electric motors.

A system of clamps which can be operated mechanically or by electromechanical means may also be used as flow shut-off means. This clamp system closes or opens the tubing 15 or 16 alternatively.

In this case, the tubing 15 and 16 would be made of medical PVC or Tygon and the system would have the great advantage of being reusable and therefore not disposable with a consequent financial saving and, optionally, of being integrated in the reservoir support .

Naturally, in order to satisfy contingent and specific requirements, a person skilled in the art may apply to the above-described embodiments many modifications and variations all of which, however, are included within the scope of protection of the invention as defined by the appended claims .

Claims

1. Haemoperfusion apparatus comprising pumping means (6), a reservoir (4) for the storage of the venous blood, an oxygenator (7) for oxygenating the venous blood, the pumping means (6) being able to draw the venous blood from a patient (3) through a receiving line (2) so as to store it in the reservoir (4) and being able to supply the blood stored in the reservoir (4) to the patient (3) through a return line (10) , after the blood has been oxygenated by the oxygenator, characterized in that it comprises blood shut-off means (14) configured for providing, alternatively, a flow connection between the receiving line (2) and the reservoir (4) or a flow connection between the receiving line (2) and the pumping means (6) .

2. Haemoperfusion apparatus according to Claim 1, characterized in that the shut-off means (14) are associated with the reservoir (4) .

3. Haemoperfusion apparatus according to Claim 1, characterized in that the shut-off means (14) are contained in the reservoir (4) .

4. Haemoperfusion apparatus according to Claim 1, characterized in that the shut-off means (14) are valve means (17, 18, 19, 25 and 26) .

5. Haemoperfusion apparatus according to Claim 4, characterized in that the valve means (17, 18, 19, 25 and

26) are three-way valves (25, 26) .

6. Haemoperfusion apparatus according to Claim 5, characterized in that the three-way valves (25, 26) are disposed upstream and downstream of the reservoir (4) .

7. Haemoperfusion apparatus according to Claim 4, characterized in that the valve means (17, 18, 19, 25 and 16) are two-way valves (17, 18, 19) .

8. Haemoperfusion apparatus according to Claim 7, characterized in that the two-way valves (17, 18, 19) are disposed upstream and downstream of the reservoir (4) and between the valve that is upstream of the reservoir (4) and the pumping means (6) .

9. Apparatus according to any one of Claims 4-8, characterized in that the valve means (17, 18, 19, 25 and 26) are operated manually, by means of compressed air, or by means of electric motors .

10. Haemoperfusion apparatus according to Claim 1, characterized in that the shut-off means (14) are clamps.

11. Haemoperfusion apparatus according to Claim 10, characterized in that the clamps are disposed upstream and downstream of the reservoir (4) .

12. Apparatus according to any one of Claims 10-11, characterized in that the clamps are operated manually, by means of compressed air, or by means of electric motors.

13. Apparatus according to any one of the preceding claims, characterized in that the pumping means (6) are of the centrifugal-pump type.