US 3731731 A
The invention relates to a device for adjusting the temperature of blood and the like fluids under sterile conditions, comprising a reservoir in the shape of a collapsible bag, in which the fluid is contacted with the outer surface of a temperature adjusting body through which a temperature adjusting medium flows, said temperature adjusting body comprising a substantially tubular rigid body passing through the collapsible bag in the assembly plane of the latter below the fluid inlet, a tight joint being provided between the bag and the tubular body at the ends of the latter.
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Description (OCR text may contain errors)
Inventors: Erik Bach Kyvsgaard, Charlottenlund; Christian Peter Simonsgaard, Holte, both of Denmark Polystan ved E. Kyusgaard, Herlev, Denmark Filed: May 4, 1971 Appl. No.: 140,118
References Cited UNITED STATES PATENTS 9/1963 Bruman ..l65/46 X United States Patent 11 1 1111 3,731,731 Kyvsgaard et a1. 1 May 8, 1973 54] TEMPERATURE CONTROL MEANS 3,171,475 3/1965 Waldman ..l65/46 x FOR BLOOD AND THE LIKE FLUIDS 3,640,283 2/1972 Bhatia 165/46 Primary Examiner-Edward G. Favors Attorney-Arnold Robinson  ABSTRACT The invention relates to a device for adjusting the temperature of blood and the like fluids under sterile conditions, comprising a reservoir in the shape of a collapsible bag, in which the fluid is contacted with the outer surface of a temperature adjusting body through which a temperature adjusting medium flows, said temperature adjusting body comprising a substantially tubular rigid body passing through the collapsible bag in the assembly plane of the latter below the fluid inlet, a tight joint being provided between the bag and the tubular body at the ends of the latter.
7 Claims, 3 Drawing Figures Patented May 8, 1973 3,731,731
2 Sheets-Sheet 2 TEMPERATURE CONTROL MEANS FOR BLOOD AND THE LIKE FLUIDS The present invention relates to temperature control means for adjusting the temperature of blood and the like fluids under sterile conditions, the fluid in question being carried to a reservoir, in which the fluid is brought into contact with an outer surface of a temperature adjusting device, through which a temperature regulating medium flows, said reservoir comprising a collapsible bag, which consists of two layers of a flexible thermoplastic sheet material, which are welded together to form a bag with a top hem for its suspen- Temperature control means of this kind are used especially during an operation where a patient is having blood supplied, which has been treated in for example an oxygenator. The blood to be supplied must not be infected and must not contain air bubbles. Furthermore, it must be treated so carefully that the blood cells are not damaged. Temperature control means for this purpose are known. They can be inserted in the tube carrying the blood from the oxygenator to the patient and may be made from stainless steel, in order to make it possible to take them apart, clean them, sterilize them, and use them again. The possibility of re-using reduces the importance of production costs, but on the other hand the sterilization is a rather extensive and costly process. For this reason, temperature control means have been proposed, which are only used once and then discarded.
A disposable heat exchanger, which is built into a reservoir in the lower part of an oxygenator, is known. The reservoir is made from hard, transparent plastic, and in a flat, vertical part, it has a cylindrical enlargement with an approximately horizontal axis. In this a cylindrical body for the regulation of temperature has been inserted, to and from the interior of which the temperature regulating medium is supplied and discharged. The blood passes in a thin layer through the interspace between the cylindrical enlargement and the temperature control body. Normally, water is used for the temperature adjustment, and in order to get a well defined surface temperature of the temperature control body, the water must be supplied with a certain pressure to give a good inner circulation and, accordingly, a good transmission of heat from the water to the transmission surface. Owing to the relatively high pressure of the water supply, there is a risk that the temperature control body will break, if the discharge tube is blocked or flattened, and thus cause a leakage of water into the blood present in the apparatus.
When designing surgical equipment it is of vital importance that the defects, which might occur, do not immediately cause a disastrous situation for the patient under treatment. Thus, in addition to a primary security in the form of easy handling, first grade materials and workmanship, and a big safety margin, the equipment should also provide a secondary security, which limits, postpones, or prevents accidents in case a defect should occur in spite of all precautions. In the above heat exchanger, a permanent risk of leakage of water into the blood exists, owing to the necessary joints between the temperature regulating body, its water supplies and the surrounding shell. Neither does a heat exchanger of this kind make it possible to prevent air from being pumped into the circulation of the patient if the supply of blood to the heat exchanger should fail.
The object of the present invention is to provide temperature control means for blood and the like fluids, in which the risk of defects occurring, which might be disastrous to the patient, is reduced to a minimum. With this object in view, the temperature control means of the invention comprise a temperature adjusting device in the shape of a tubular, rigid body, passing through the collapsible bag in the assembly plane of the side walls of the bag below the fluid inlet, a sealing being provided between the tubular part of the said temperature adjusting device and the bag.
Using a collapsible bag as the reservoir, and enclosing the temperature control device in the latter, has the advantage of the passage being blocked when the reservoir is emptied, since this will result in that the bag collapses, whereby the outlet is blocked. Furthermore, an easy and reliable sealing between the temperature regulating body and the bag becomes possible, for example by means of a clamp or a rubber band pressing the parts of the bag surrounding the tubular body against the latter. This kind of assembling is inexpensive. These advantages are obtained without loosing the usual advantages of reservoirs with flexible walls. The fluid follows flexible walls and is thereby prevented from splashing, whereby degassing is facilitated, and the upper part of the bag serves as a bubble trap, thus preventing bubbles and foam from penetrating into the circulation of the patient.
A tube with ribs and corrugations, extending approximately perpendicular to the axis of the tube, is preferably used as transmission surface according to the present invention. This increases the outer surface of the temperature adjusting device and, since the blood mainly passes in between the corrugations, a big cross section of flow is obtained, which prevents air bubbles from being carried along.
In an embodiment of the temperature adjusting device, the corrugation is helical, arid the tubular body has moulded end closures, which have been moulded in situ to fill out the corrugations at the ends of the tubular body of the temperature adjusting device to provide a tight joint. A helical corrugation is especially simple and consequently economical to produce. Besides, it has turned out to be of no importance whether the corrugations are extending perpendicular to the axis of the tube or not. The moulded end closures and the filling out of the corrugations at the ends of the tubular body ensure a good tightening against the bag, and the simultaneous moulding simplifies the production, and the temperature adjusting body is easily provided with inand outlets, since these can be formed simultaneously with the moulding of the end closures.
In a preferred embodiment of the invention, the temperature adjusting body passes through the reservoir at both sides. The temperature adjusting body obtains only with difficulty the same strength at the ends as in the tubular part of it. This is partly due to the end closures proper consisting generally of sheet metal or moulded plastic, partly to the joining, which may be adhesively along the circumference of the end closure. When the temperature adjusting body passes through the reservoir at both sides, an extra safety is obtained against the temperature adjusting fluid penetrating into the blood, in case the tubular body should break, owing, e.g. to an increased pressure caused by a blockade of the outlet for the temperature adjusting fluid.
According to the invention, the interspace between the bag and the transmission surface may be determined by means of two shells enclosing the bag adjacent to the temperature adjusting body. Thus, the flow can be controlled in order to obtain an even utilization of the heat transmission surface. To ensure a mainly linear distribution of the flow along the transmission surface, the opening between the shells above the temperature regulating body is increasing in width towards the ends, according to a preferred embodiment of the invention.
In the following, the temperature control means of the invention will be explained in detail with reference to the embodiment shown in the accompanying drawings, in which FIG. 1 is a front elevation of the temperature control means,
FIG. 2 is a sectional view along the line II II of FIG. 1, and
FIG. 3 a horizontal view along the line III III of FIG. 2.
The control means according to the invention consists of a closed bag 1, made from two layers of plastic, which have been welded together by means of a welding seam 2 along the edges. The bag is suspended at its upper edge, e.g., by means of a rod 4 passing through a hem 3. Thereby a closed reservoir is formed, in which, for example, the temperature of blood treated in an oxygenator or in a dialysis apparatus can be adjusted before being brought back into circulation in a patient being subjected to an operation. The blood is let off from the lower rounded part of the bag, to one wall of which a connecting piece 5 of plastic has been welded for the fixing of an outlet tube 6. The inlet of fluid can take place through an opening 7 in the welding seam 2 at one side of the bag 1. The opening 7 is connected with an inlet channel 8, which may form an integral part of the bag 1 by providing an extra welding seam on an enlargement of the two layers of plastic, from which the bag is made. To make sure that the bag will collapse if it is emptied, for example owing to interruption of the blood supply, the inlet channel may have a curve 10, facing downwards to form a sort of water trap, e.g., by letting the welding seam 9 join the outline of the bag below the opening 7 in the welding seams 2 of the bag. The inlet channel 8 may form a part of an oxygenator or a dialysis apparatus, to which the heat exchanger is connected, but may also have coupling means to connect it with other apparatuses, since the temperature control means of the invention may be used also in other cases where a temperature adjustment of a fluid under sterile conditions is desired.
The bag 1 has extensions 11 near the bottom of each of the two side seams. The side seams are interrupted in each of these extensions along the part parallel to the side edge. The extensions 11 thus form sleeves, which are preferably placed opposite one another, and through which a heat transmission surface 12 is passed, preferably in the form of a temperature adjusting body 13 of cylindrical outline. Around the sleeves resting against the ends of the cylindrical surface 12 of the temperature adjusting body 13, a rubber band 14 is placed, said band being secured with a clamp of stainless steel. Thereby a tight joint is provided between the bag 1 and the temperature adjusting body 13. In order to make the fluid in the temperature control means follow the surface of the temperature adjusting body 13 during its passage, two half-shells 15 of a cylindrical shape corresponding to that of the heat transmission surface 12 are enclosing the bag. The interspace between the half-shells along the rims 16,17, the halfshells themselves, and the heat transmission surface determine the distribution of flow over the transmission surface. By making the distance between the rims 16 (FIG. 2) suitably small and by giving the opening a slightly increasing width towards the ends, a quite even distribution of flow is obtained, which is important for the bubble removal, since nowhere must the speed of the flow be allowed to increase to such an extent that air bubbles, if any, cannot rise to the upper part.
The heat transmission surface 12 has been made with a corrugated surface in order to obtain a considerable heat transmission by compact dimensions.
FIG. 3 shows a section through the heat transmission surface, where the corrugations 18 are to be seen. The heat transmission surface may advantageously be made from a compensation tube of a resistance seam welded sheet of stainless steel. This makes the corrugation helical, which is, however, without importance for the flow passing the temperature adjusting body. The flow passes the channels formed between the corrugations, said channels being outwardly defined by the sheet material of the bag, which is kept close to or at a small distance from the corrugations by means of the halfshells 15. The temperature adjusting body 13 has end closures 19, through which the inlet 20 and the outlet 21 for the temperature adjusting fluid are carried. The end closures 19 can be moulded in situ from plastic and simultaneously the corrugation at the ends of the tube may be filled out to provide a surface, against which the plastic can tighten. Thus, the material for the end clo sures may be filled into a rubber mould, in which the end of the corrugated tube is inserted prior to the setting of the plastic. If desired, the rubber mould may be left on the end closure. The inlet 20 and the outlet 21 may be throughgoing tubes, to avoid expansion of the temperature adjusting body 13 in the longitudinal direction due to the fluid pressure. The corrugated tube is submitted to a compression test before being cut in the necessary length for a transmission surface. Consequently, a considerable safety against leakage is obtained against penetration of the temperature regulating medium into the bag, where the blood is. Furthermore, the end closures in the proposed construction are rather weak, and will break before the transmission surface, if, by accident, an increase of pressure in the temperature adjusting medium takes place, giving additional safety. For distribution of the temperature adjusting medium in the tubular body, the inlet tube 20 and the outlet tube 21 are provided with holes 23, placed at short intervals, preferably tangentially to the axis of the tubular body.
Wen not using through-going tubes in the temperature adjusting medium, the halfshells 15 may have end walls, which prevent a longitudinal expansion of the corrugated heat transmission surface by enclosing the end closures of the temperature adjusting body.
To obtain the biggest possible purity of the blood or the fluid, for the temperature adjustment of which the temperature control means is to be used, a filter may be built into the lower part of the bag between the tubular body and the outlet to retain solid particles and the like.
1. Temperature control means for adjusting the temperature of blood and the like fluids under sterile conditions, comprising a reservoir consisting of a collapsible bag made from two sheets of flexible plastic welded together at the edges, and being suspended from a support at the top, and
a temperature adjusting means in the shape of a substantially tubular rigid body extending through the collapsible bag in the plane of assembly of the latter below an inlet for the fluid, and being provided with an inlet and an outlet for a temperature adjusting medium,
a tight seal being provided between the collapsible bag and the tubular body at the ends of the latter.
2. Temperature control means as set forth in claim 1, in which the tubular body has ribs or corrugations extending substantially perpendicular to its axis.
3. Temperature control means as set forth in claim 2, in which the tubular body has helical corrugations, and moulded end closures, the outside corrugations being filled up at the ends of the tubular body.
4. Temperature control means as set forth in claim 1, in which the tubular body extends outside the reservoir at both ends.
5. Temperature control means as set forth in claim 1, in which two half-shells enclose the collapsible bag adjacent the tubular body.
6. Temperature control means as set forth in claim 5, in which the half-shells have end walls enclosing at least the border of the end closures of the tubular body.
7. Temperature control means as set forth in claim 5, in which the opening between the half-shells increases in width towards the ends of the half-shells.