WO1992002267A1

WO1992002267A1 - Heat insulating canister for handling infusion liquid

Info

Publication number: WO1992002267A1
Application number: PCT/SE1991/000518
Authority: WO
Inventors: Peter Nielsen; Leif Strand
Original assignee: Peter Nielsen; Leif Strand
Priority date: 1990-08-02
Filing date: 1991-08-02
Publication date: 1992-02-20
Also published as: AU8331991A; SE9002552D0; SE9002552L; SE468542B

Abstract

The invention refers to a canister, divided lengthwise into two identical halves, of light, heat insulating material with a side wall and end walls for handling human liquid for infusion supplied in a container (23). The canister consists of expanded polypropylene and the two halves thereof are detachably interconnected by positive engagement at undercut ribs and grooves on the surfaces of the halves in the parting line.

Description

HEAT INSULATINGCANISTER FOR HANDLING

INFUSION LIQUID

The present invention refers to a heat insulating canister for handling human liquid for infusion (including for example liquid for irrigation, antibiotics and cytosta- tics) which is supplied in a container, often a plastic bag, but the container can also be a bottle of plastic or glass. The liquid for infusion (replacement blood, nutrient solution etc.) supplied to the human body during surgery should keep the physiological temperature, i.e. a tempera¬ ture adjusted to the body temperature normally in the range between 30 and 40 °C, above all in order to prevent the chilling of the patient but also because supply of the li¬ quid for infusion at this temperature gives the patient a more pleasant feeling than if the temperature of the liquid for infusion has a lower temperature than the body tempera¬ ture, for example room temperature. A person who has met with a serious accident - it may for example concern an accident in mountain country during wintertime - might have been chilled already at the site of the accident and/or while being transported in a cold ambulance, helicopter or other transport vehicle from the site of the accident to the hospital where further cooling can take place for exam¬ ple as a consequence of anaesthetic when the natural tempe¬ rature control system of the body functions worse than normally, the patient losening heat, or as a consequence of a surgical operation; during abdominal opening vaporizing of liquid takes place with accompanying chilling, which may amount to about 700 ml/h. After an operation the patient thus runs the risk of beeing chilled to about 28 °C which amounts to treatment in a respirator. If further chilling should take place, the risk of incurable auricullar fibril- lation is imminent. When removed from a supply depot a

SUBSTITUTESHEET liquid for infusion holds principally room temperature, accordingly a temperature of about 18 °C, and considering the risk of chilling it is thus not suitable to give it to the patient at this temperature. Hence, so called blood warmers are used, which are electrically heated and there¬ fore intended for connection to the mains and thus require access to an electrical connection. The container with liquid for infusion in a customary way is hanged on a stand of that kind which is available for this purpose, and the liquid for infusion is allowed to flow through the blood warmer on its way to the patient in order to impart to the liquid for infusion on its way from the container to the patient a temperature which makes the supply to the patient pleasant. Apart from being expensive to acquire (at present about 6,000 SEK) , such a blood warmer requires at each time it is being used a special insert bag which at present costs about 60 SEK. In cases of acute accidents, there is not always time to get the blood warmer going quickly enough and it can not be used for infusion at the site of the accident since it is operated from the mains. As far as meeting the demand of preventing chilling of the patient, the blood warmer is thus not quite ideal with respect to neither costs nor use.

In SE-A-8406229-8 there is suggested a movable tempe- ring system for liquid for infusion including a canister of light, heat insulating material with a side wall and end walls for handling the liquid for infusion supplied in a container, the canister being diveded lenghtwise in two halves in order to be placed around the container enclosing the same.

The invention refers to a canister of this kind. It is not particularly evident from SE-A-8 06229-8 how the two canister halves are kept together in the posi¬ tion enclosing the container. Considering the canister being used in case of an accident and then taking into account that it must be handled under severe conditions and maybe at low environmental temperature, it is a requirement that the canister is made of a durable material and it is also required that the canister can be applied to the con- tainer without using separate devices and/or devices that are difficult to handle for fastening the canister around the container.

In order to satisfy these requirements, the canister according to the invention has obtained the characterizing features of claim 1.

The liquid for infusion can be warmed to a suitable temperature (30-40 °C) in a heating chamber or a microwave oven or, as suggested in SE-A-8406229-8, by a heating coil which is connected to the electric system of an emergency vehicle in order to be kept at this temperature by later storing in the heat insulating canister which allows the liquid for infusion to be transported to and/or used at the site of the accident while maintaining the temperature thereof. Polypropylene is a strong material which withstands rough handling also under harsh conditions. Thus, the ribs and grooves arranged as a quick-lock for the two canister halves can be brought repeatedly into and out of engagement also at low environmental temperatures without the material being crumbled to bits and the locking effect thus being lost. The two canister halves in an easy way can be inte- rengaged in the position enclosing the container only by pressing them together. It is essential with respect to clinical use that the material is not crumbled to bits at the ribs and grooves since existing bits then would be able to contaminate open wounds etc.

The heat insulating canister of polypropylene is cheap in manufacture - about 250 SEK - and can be used repeatedly - 100 times or more - which apart from the above-mentioned advantages involves a considerable saving compared with the conventional blood warmer or container of polystyrene.

DE-A-38 00 283 and US-A-4 804 367 describe flexible insulated envelopes which are wrapped around the container (plastic bag) and fastened by means of Velcro tape, the in¬ sulation being less effective than if a heat insulating canister is used.

The invention will be described below with reference to the accompanying drawings, wherein FIG. 1 is a side view of a heat insulating canister according to the invention,

FIG. 2 is an end view of the canister in FIG. 1 viewed from above,

FIG. 3 is a side view in a reduced scale showing the canister with existing bag for liquid for infusion suspended from a stand,

FIG. 4 is a plan view of of one of the canister halves,

FIG.5 is an axial sectional view of the canister taken along the line V - V in FIG. 1, and

FIG. 6 is an enlarged cross sectional view of the canister taken along the line VI - VI in FIG. 1.

The heat insulating canister according to the inven¬ tion is indicated at 10 and comprises end walls and a side wall with bevelled edges between side wall and end walls. The. canister as a whole shall be made of expanded polypro¬ pylene, EPP, which is marketed by BASF under the designa¬ tion Neopolen P 9010V. The material has a weight by unit of volume of 30 kg/m³ and has excellent insulating capacity; the coefficient of thermal conductivity is 0.039 W/Km at 20 °C. It is manufactured completely without freon and has a smooth, rather sleek surface which is cleanable in order to satisfy highly raised hygienic demands. It is flame-proof, shock-proof, and tenacious and is not crumbled to bits. In the present case the canister has an octagonal cross section but it can have any other outer shape. It consists of two identical halves 10A and 10B having undercut ribs and corresponding undercut grooves for interengagemen , each half in the parting line along one long side thereof having a rib 11 and along the other long side thereof having a groove 12 and along the short side having a rib 13 and groove 14, FIG. 4. Polypropylene has a certain elasti¬ city which allows the undercut ribs and grooves to be pressed to interengagement without the material being broken.

Each canister half has a longitudinal slot 15 with a clear glass or plastic tube pressed thereinto, FIGS. 5 and 6, said slots being positioned opposite to each other in the assembled canister. In one end wall there is arranged a central square opening 17, and in the other end wall a cen¬ tral slot 18. A cord 19 with knots at the ends is threaded through this latter end wall and on this cord a washer 20 is mounted, said washer being shaped as a hook 21 having a through aperture 22. It should also be mentioned that the canister on the outside thereof can be shaped in such a way that each half forms a finger hold or a handle in order to be more easily gripped when the canister is put together or separated.

When handling liquid for infusion supplied in a plas- tic bag of conventional, well-known type or in a plastic or glass bottle by using the canister described the procedure is as follows: The container with liquid for infusion (replacement blood, nutrient solution etc.), in this case a plastic bag 23, is put into a heating chamber or a micro- wave oven for warming to a suitable temperature which lies between 30 and 40 °C. The bag can be provided on the out¬ side thereof with a temperature strip with liquid crystals in order to indicate the temperature of the contents of the bag. When the liquid for infusion is to be given to a patient, a canister of the described embodiment is taken out and opened manually by drawing the both canister halves apart, the halves being disengaged at the undercut ribs and grooves without the material being crumbled to bits, the material having enough resiliency to yield elastically when the ribs are pulled out of the grooves. One of the halves of the canister is put down with the cavity formed therein facing upwards, said half lying firmly in this position on its central plane external surface. The bag with liquid for infusion is taken out of the heating chamber or microwave oven, respectively, and is placed in the trough formed by said half canister, an outlet socket 24 at one end of the bag being passed through the opening 17. The hook 21 on the washer 20 is hooked to the suspension slot provided in a flap 25 at the other end of the bag, the washer 20 then being put into the slot 18 as shown in FIG. 5. The other half of the canister is now put on as a lid and the two canister halves are pressed together in order to lockingly engage the undercut ribs and grooves and keep the canister together. The bag is now hung up directly by means of the washer 20 by threading it onto a hook 26 on a conventional suspension stand 27, FIG. 3, the light canister being supported by the stand via the bag. By this suspension the the canister thus does not have to be loaded by the weight of the bag and its contents. The small strain caused by the light container is negligible. It should be pointed out here that the cord 19 and the washer 20 can be excluded and the flap 25 instead be withdrawn through the slot 18 in order to be engaged directly with the hook 26. The cord 19 can also be fastened directly to the flap 25. Thus, in these cases also the canister will be supported via the bag. When the bag with liquid for infusion is suspended thus enclosed by the heat insulating canister the liquid for infusion can maintain an adequate (fysiological) tempe¬ rature for supply to the patient for a long time. It has become apparent that the temperature of the liquid for in- fusion initially having a temperature of 40 °C during the next 8 hours falls only about 10° in an environment of room temperature. With the warmed liquid for infusion so well heat insulated it can also be transported in the canister without any appreciable temperature decrease to a site of accident for administration of the liquid for infusion at fysiological temperature at the site of the accident.

The liquid level can be read in one of the slots 15 against the incident light coming through the opposite positioned slot 15 in the other half of the canister. It is important to be able to do this especially when the liquid in the bag is running low and the slots 15 are consequently provided only along the lower part of the canister but, of course, nothing prevents extension of these slots over sub- stantially the total length of the canister.

On such occasions when a rapid infusion is needed and an approved cuff therefore is mounted around the bag in order to generate a pressure therein, also the pressure cuff can be placed inside the canister and the tubes to the manometer and the pump extended through the opening 17 and/or the slot 18.

Since the heat insulating canister can be used innu¬ merable times and is cheap to manufacture, the price at each occasion it is being used will be insignificant and only a smaller fraction of that cost which has to be taken into account when a conventional blood warmer with an insert bag of throw-away type is used every time liquid for infusion is supplied a patient. The canister does not come into contact with the liquid for infusion or infusion unit and thus has no effect on the sterility of the liquid for infusion.

As mentioned above, the existing fluid can also con¬ sist of antibiotics or cytostatics. In that case the canis¬ ter is used for maintaining a low temperature of the liquid while the liquid is supplied at a lower rate than is normal in order to prevent a chemical inflammation in the vascular walls.

Claims

1. Canister of light, heat insulating material with a side wall and end walls, for handling liquid for infusion supplied in a container (23), said canister being divided lengthwise into two halves, c h a r a c t e r i z e d in that the light, heat insulating material comprises expanded polypropylene, and that the two halves (10A, 10B) of the canister (10) are detachably interconnected by positive engagement at undercut ribs (11, 13) and grooves (12, 14) arranged on and in, respectively, the surfaces of the halves in the parting line.

2. Canister as claimed in claim 1, c h a r a c ¬ t e r i z e d in that slots (15) are arranged in the side wall of the canister (10), located opposite to each other for inspection of the contents of the canisters.

3. Canister as claimed in claim 2, c h a r a c ¬ t e r i z e d by a clear tube (16) of glass or plastic being inserted in each slot (15).