GB2517092A

GB2517092A - A polyurethane foam article

Info

Publication number: GB2517092A
Application number: GB1416952.8A
Authority: GB
Inventors: Ian Malcolm Vickery
Original assignee: DENTMED Ltd
Current assignee: DENTMED Ltd
Priority date: 2013-03-01
Filing date: 2013-08-27
Publication date: 2015-02-11
Anticipated expiration: 2033-08-27
Also published as: GB201308157D0; GB201416952D0; GB2513427B; GB201303667D0; GB201315214D0; GB2513427A; GB2517092B

Abstract

A polyurethane foam article has a hydrophobic polyurethane foam layer and a hydrophilic/haemophilic polyurethane foam layer, the article having at least one cavity therein, the at least one cavity having a corresponding vent extending to the exterior of the article, the at least one cavity containing an analgesic fluid. This forms a pad. The cavity may be formed during the manufacturing process, which comprises dispensing a non-polymerised layer onto a hydrophilic/haemophilic layer, and polymerising the hydrophobic layer. Metal tongues are used to keep the hydrophilic layer in the correct position in the mould. Once polymerisation is complete the tongues are removed, to form a cavity or chamber in the interior of the article, which is then filled with analgesic using a syringe inserted into the vent. The analgesic is released when the article is used. Also described is a similarly layered article where at least one of the layers contains barium sulphate for radio-opacity. Preferably, the barium sulphate is in the hydrophobic layer.

Description

A POLYURETHANE FOAM ARTICLE

Cotton swabs for use during a surgical procedure predate the times of Hippocrates, Aristotle and Galeu et al and although cotton quality has improved the current BSEN 14079:2003 still states that "not more than slight traces of leaf, pericap seed-coat or other impurities", section 3.1 -performance requirements! The present invention relates to a polyurethane foam article for use during a surgical procedure or when dealing with blood/fluid loss in other situations.

Prior to, during, or immediately following a surgical procedure, it can be necessary for articles such as sponges or gauzes to be placed within, and for removal from, an anatomical cavity, a wound cavity, or a surgical site.

Sponges, gauzes, or wadding are also frequently used during surgery to isolate and/or protect organs not directly involved in the surgical procedure and to absorb/remove fluids such as blood or other bodily fluids.

I

Despite mandatory procedures to confirm removal of such articles they are sometimes overlooked and remain within the patient following completion of the surgery.

Further surgical procedures may then be reguired resulting in additional avoidable risks to the patient and incurring medico-legal implications.

The most commonly used method of accounting for items temporarily inserted into a body or wound cavity during a surgical procedure is to record the number of items initially available at the start of the procedure and to manually confirm the removal of the same number of items at the end of the operation.

However it is possible for such items to migrate within the body or wound cavity during surgery and, in addition, it is common for such articles to become soaked in blood/or other fluids so that they appear to be part of the surrounding bodily tissues or organs.

Thus it can be difficult to manually locate and remove all articles inserted into the body or wound cavity at the end of the surgical procedure and there can be several factors associated with retained foreign bodies, [RFB,s], resulting in the diagnosis of GOSSYPIBOMA/or TEXTILOMA.

Possible causes for such an event are -Emergency procedures.

Lengthy procedures.

Unexpected changes in procedures.

Patients with a high BMI -Obesity.

Prolonged operations.

Operating room environment.

-Poor communication.

-Inexperienced/untrained staff.

-Lack of cooperation between team members.

-Interrupted swab/instrument counts.

-Different nursing teams.

-Lack of standardised count process.

Prior Art.

It is known to incorporate a radio-opaque thread or thin sheet containing Barium Sulphate in a surgical swab/sponge visible on an X-ray image of the patient.

Barium Sulphate is a suitable material for such applications as it is an insoluble salt that is not mobile, is chemically inert and non-injurous to body tissues.

US 2005/0049563 Al. Describes a surgical sponge comprising a radio-opaque marker having a high radiographic density and a distinctive X-ray recognisable shape. The marker has an X-ray density equivalent to at least 0.lgm/cm2 of Barium Sulphate which produces an X-ray image with high contrast and distinctive shape that is readily differentiated from images produced by other items and structures commonly seen in X-rays of post-operative patients.

However, as the radio-opaque thread, sheet, or marker is generally small compared to the size of the sponge or swab this degree of radio-opacity is frequently inadequate in identifying the complete sponge/swab on an X-ray image even when MRI or CT scans are used. In addition, if the sponge/swab is damaged, cut, or becomes fragmented during a surgical procedure It may only be possible to locate those parts of the sponge/swab that include the thread, sheet, or marker.

Thus with the known arrangements discussed above it is not possible to accuratly ensure that all articles have been removed from the patient at the end of a surgical procedure.

At its most general, a first aspect of the present invention provides a polyurethane foam article for surgical use made from a mixture of specific formulations of polyol/isocyanate and barium sulphate that have sufficient radio-opacity to produce a visibly distinct X-ray image of the foam article.

According to this aspect of the invention there may be provided a polyurethane foam article for surgical use, the foam artiole oomprising a hydrophobic polyurethane foam layer and a hydrophilic/haemophilic polyurethane foam layer, at least one of the layers containing barium sulphate.

Barium Sulphate is incorporated into the hydrophobic polyurethane foam section of the article and extends into the hydrophilic/haemophilic section of the foam article resulting in sufficient radio-opacity to produce a visibly distinct shadow on an X-ray image.

Thus the shadow produced on an X-ray image is that of both sections of the unit rather than the shadow produced on an X-ray image by known sponges/swabs that include a radio-opaque thread, sheet, or a marker.

The X-ray density equivalent of O.94gm/CC3 indicates a 3 dimensional distribution of Barium Sulphate through the polyurethane foam article rather than a 2 dimensional X-ray density equivalent of O.lgm/002 described in prior art.

In the unlikely event of fragmentation of the polyurethane foam article -fragments may have sufficient radio-opacity to produce a visibly distinct shadow on an X-ray image unlike in known sponges/swabs where only those fragments having thread, sheet, or marker attached may produce a visible shadow on an X-ray Image. Thus with the polyurethane foam article of the present invention it is possible to account for and remove articles placed in a body or wound cavity during a surgical procedure even in circumstances where an article may have become fragmented.

It is possible, during manufacture of polyurethane foam article for surgical use, for one or more cavities to be made within the article, the or each cavity having a vent extending to the exterior of the article. The cavity or cavities may then contain an analgesic or haemostatic fluid. The fluid is absorbed into the hydrophilic/haemophilic polyurethane foam layer, and the hydrophobic polyurethane foam layer restricts escape of the fluid, in the absence of an external trigger.

When the article is compressed, to provide that trigger, the fluid will then be released, enabling the analgesic or haemostatic fluid to act on the patient.

Indeed, this use of an analgesic fluid in a polyurethane foam article is applicable to articles which do not contain barium or other radio opague material. The article can still act as a swab, and will then be one which releases the analgesic fluid. Alternatively the article may be a pad which may be applied to the exterior of the patient, to permit release of the analgesic fluid at an appropriate time.

Thus, according to this aspect of the invention, the present invention may provide, A polyurethane foam article for surgical ilse, the foam article comprising a hydrophobic polyurethane foam layer and a hydrophilic/haemophilic polyurethane foam layer, the article having at least one cavity therein, the at least one cavity having a corresponding at least one vent extending to the exterior of the article, the at least one cavity containing an analgesic or haemostatic fluid.

The materials used to form the hydrophobic polyurethane foam layer and/or the hydrophilic/haemophilic polyurethane foam layer may be the same as in the first aspect.

Whether barium is present or not, the fluid may be e.g. bupivacaine, diclofenac or aspirin dissolved in a carrier.

The article according to the first aspect may be formed by (i) disposing a non-polymerised hydrophobic layer comprising a polyol, isocyanate and barium sulphate composition over a hydrophilic/haemophilic layer; and (ii) polymerising the hydrophobic layer; wherein before and/or during the polymerising step, the barium sulphate of the non-polymerised hydrophobic layer partially migrates or egresses into the hydrophilic/haemophilic layer.

The article according to the second aspect may be formed by the steps of (i) disposing a non-polymerised hydrophobic layer comprising a polyol and isocyanate composition over a hydrophilic/haemophilic layer; and (ii) polymerising the hydrophobic layer; wherein the method further includes: forming at least one cavity in the article, the at least one cavity having a corresponding vent extending to the exterior of the article; and inserting an analgesic fluid into the cavity.

Another method according to the second aspect may comprise inserting the analgesic fluid into at least one cavity as a pre-formeci article where the article comprises a hydrophobic polyurethane foam layer and a hydrophilic/haemophilic polyurethane foam layer, the article having at least one cavity therein, the at least one cavity having a corresponding at least one vent extending to the exterior of the article; Embodiments of the present invention will now be described by way of example with reference to the accompanying pictures.

The polyol composition is as listed below -Polyoxyalklene triols.

Triethanolamine.

Dipropylene glycol.

Triethydiamine.

Organo-modified polysiloxanes.

09-11 alcohol ethoxylate.

2-f [2-dimethylamino]ethyl]methylamino}ethanol.

With an isocyanate composition listed below - Methylenediphenyl diisocyanate. [MDI I -Homopolymer.

This combination of Poiyol and Isocyanate provides the formulations used in the manufacture of the Dentmed V-Pack.

The ratio's required to provide the specifications for the current poiyurethane article are based on a ratio of 2.2 parts of polyoi to 1 part of isocyanate.

Small V-Swab.

16.5 grams of polyol.

7.5 grams of isocyanate.

3.8 grams of barium sulphate Moulded in a 2 impression tool -above ratio's may be varied 1-2% depending on mould temperature.

Medium V-Swab.

15.4 grams of polyol.

7 grams of isocyanate.

3.5 grams of barium sulphate.

Moulded in a 1 impression tool -above ratios may be varied 1 -2% depending on mould temperature. ii

Large V-Swab.

49 grams of poiyoi.

22 grams of isocyanate.

11 grams of barium suiphate.

Moulded in a 1 impression tool -above ratio's may be varied 2 -3% depending on mouid temperature.

The above formulations are required to form the HYDROPHOBIC section of the present invention.

5905/102 -High Density Foam System.

This poiyoi is a mixture of polycis -Butane did.

Benzenepropanoic acid.

3, 5-bis [ 1, 1-dimethylethyl]-4-hydrcxy.

C7-9 branched alkyl esters [stabilizer] Glycerine.

Silicone surfactants.

Triethylene diamine.

The Isocyanate is an MDT.

Diphenyimethane -4, 4-diisocyanate -ISO 135/159.

Tn phenyl phosphite -TTP.

This formulation of polyol and isocyanate is that recommended by the manufacturers with the ratio of 100 parts polyol to 81 parts of isocyanate and a 1-3% tolerance to allow a variation in product hardness.

This formulation provides the HYDROPHTLIC/HAEMOPHILIC section of the present invention.

The V-pack represented the FIRST polyurethane foam article to be developed for intra-cavity use within the human body during & surgical procedure.

As there was no previous British Standard for such a polyurethane foam article a list of specifications was developed, and confirmed with the MHPA and was patented in the UK, GERMANY, USA, and JAPAN.

The present invention is based on 40 YEARS clinical use of a polyurethane foam for intra-cavity use.

Dentmed V-packs are designed to act as a barrier to the passage of fluids or solids into the lungs and to the escape of anaesthetic gases into the operating area. -In I-,

This polyurethane foam is therefore HYDROPHOBIC and is specifically designed to absorb minimal amounts of blood/fluid at its surfaces but predominantly to act as a barrier whilst adapting to any changes in shape of the cavity within which it is placed.

The present invention reguires a section of the above HYDROPHOBIC foam acting in MUTUALTSTTC SYMBIOSIS/MLJTUALTSM with a section of HYDROPHILTC/HAEMOPHILIC foam with embedded X-RaY DETECTABLE THREAD within cotton tape and extending from the junction between the two sections of the unit.

Specifications for the X-ray detectable tape and thread.

Yarn decitex -3,800+/-10%.

No of filaments -nominal.

Wrapper Yarn [tpi] -7 -10 tpi.

Minimum tenacity -l.OCn/tex.

Composition by weight -Barium Sulphate minimum 60% -Pharmaceutical Grade.

Cytotoxicity -ISO B55736.

Acute Systemic Toxicity -ISO B55736.

Intracutaneous Reactivity -ISO BS5736.

Skin Irritation -ISO BS5736.

Contact Sensitsation -ISO BS5736.

Biocompatability & Toxicity -no adverse comments.

Additional Specifications for the Cotton Tape.

Warp Yarn: 300 denier Optic White Dyed Yarn 29 ends intermingled.

Weft Yarn: 300 denier Optic White Dyed Yarn 1 end intermingled.

X-ray thread 2800 denier blue twisted yarn.

Warp density 75.0 ends per cm.

Weft density 8.0 courses per cm.

Fig. 1 then illustrates mculds that may be used to manufacture swabs in accordance with the invention as can be seen from the Dual small mould. A mould may be configured to produce more than one swab in a single process.

In order to maintain the correct positioning of the hydrophilic/haemophilic section one metal tongue is used in the small moulds, two tongues for the medium, and three tongues for the large moulds -see Fig. 1 referred to above. is

Once the polymerisation process has been completed, the metal tongue or tongues are removed from the resulting article. This has the effect of forming one or more chambers in the article, with the number of chambers corresponding to the number of tongues used. The removal of the tongue or tongues also means that any such chamber and event extending from it to the exterior of the article, to form a vent to the chamber or chambers.

The vent can then be used to permit the introduction of a haemostatic or analgesic fluid into the chamber created within the article. The compression of the article may then permit release of the fluid either during or prior to completion of the surgical operation in which the article is used.

The hydrophobic foam layer is allowed to polymerise over the hydrophilic/haemophilic section trapping the x-ray detectable tape, forming a strong adhesive bond, and partially invading the section of hydrophilic/haemophilic foam whilst carrying more barium sulphate into its cell structure.

As mentioned previously, compression on the CXT, or the digital extensions of the swabs of sizes Digital 1 and Digital 2 will allow release of the fluid either dnring or prior to completion of surgery.

Fig. 2 then illustrates the position of the X-ray detectable tape in swabs in accordance with the invention.

Following quality control procednres, each polynrethane foam article is sealed in a steam sterilisable package in order to carryout porous load autoclaving at 134 degrees C 32 PSI followed minus 50 bar vacuum drying.

Embodiment 1.

currently used cotton swabs compliant with ESEN 14079:2003 are manufactured to multiple sizes whilst the current polyurethane foam articles are made to set dimensions with the small and medium sizes having the CEXT extension to enable use in otherwise difficult areas to reach thus the V-Swab differs in all aspects from the current cotton swab. The corner extension -CEXT -is designed to allow single finger location and compression of the V-SWAB to enable suction to be accurately applied to a specific anatomical area -of particular value in plastic surgery, neurosurgery, ophthalmic surgery, and other surgical specialities.

Fig. 3 illustrates examples of swabs of different sizes in accordance with Embodiment 1. Sizes Digital 1 and Digital 2 correspond to one digit (finger) and two digit (finger) sizes respectively. The CEXT extension is illustrated in Fig. 4.

Embodiment 2.

This embodiment is similar to embodiment 1. Fig. 5 illustrates the absorption and release of blood by the swab.

Compression followed by release allows inbuilt suction to be transferred to the -hydrophilic/haemophilic section maximising the volume of blood/fluid drawn into the foam article.

Prior to initial use this external surface should be moistened with saline to allow Its cell structure to become more flexible and thus receptive to blood/fluid absorption.

Following a series of compression and absorption -the V-swab can then be emptied by squeezing over a measuring bowl and the whole sequence repeated as required.

It should be noted that this discharging process occurs through both the external surface of the hydro/haemophilic layer and through the tongue vents shown in Fig. 6.

With this invention it is likely that just ONE polyurethane foam article/unit maybe required per operative procedure -it is therefore very unlikely that such a single article/unit would be misplaced/retained following completion of the procedure -however should such an event occur then the presence of Barium Sulphate within this polyurethane foam article plus the firmly attached raytec tape allows a greater likelihood of locating and removal of a retained unit following completion of surgery.

A surface located marker or a silent' marker within the article may add a further safety feature in that the detail on these markers may show the MONTH and YEAR'' -of manufacture, or the source of manufacture.

With the reduction in the numbers of units/swabs to be required during a procedure, with single unit/swab use per procedure, and with high probability of radiographic location of a retained unit -the possibility of gossypiboma/textiloma is significantly reduced.

Fig. 7 illustrates blood absorption in a swab according to the invention.

Fig. 8 is another view of the X-ray visible thread.

Fig. 9 shows how the Barium Sulphate penetrates from the hydrophobic section into the hydrophilic section of the swab.

In Fig. 9, the upper part of the swab is hydrophobic and the lower part is hydrophilic. The penetration of the Barium Sulphate is also illustrated at the X-ray view of Fig. 10.

As mentioned above, the removal of the metal tongue or tongues of the article/swab results in a cavity or cavities within the swab. Figs. nato ilcand 12a to l2c then show the introduction of a haemostatic or an analgesic fluid into the swab. Figs. ha and llb show that the respective swabs are the size of one and two fingers. Figs. hib and lb show the introduction of such a fluid into one size of swab (the one finger sized swabs), and Figs. h2b and 12c show the introduction of the fluid into another size of swab (the two-finger sized swab) . The process is similar, with the fluid being loaded into a syringe, the syringe being inserted through the vent to a depth corresponding to the chamber within the swab, and then the fluid being expelled from the syringe into the chamber.

As mentioned previously, compression on the CEXT, or the digital extensions of the swabs of sizes Digital 1 and Digital 2 will allow a release of the fluid, either during or prior to the completion of surgery.

Embodiment 4.

In all the above embodiments, the article contains a barium compound, and may also have an X-ray visible tape, to provide radio-opacity. However, in the fourth embodiment, no such compound or tape is provided. This fourth embodiment may be a swab or pad. The manufacture of the swab or pad, and the other various materials used to form the swab or pad, may be the same as in the previous embodiments. In this embodiment, as in Fig. 3 for the small and medium sized articles, analgesic fluid is introduced into the chamber or chambers within the swab or pad, to enable the slow release of that fluid during or prior to completion of surgery or in order to help relieve muscle or joint pains, when the article is used as a pad. Moreover, these articles can then be used repeatedly as pads, in combination with a heat-providing package.

Additional features of the invention are discussed in the following clauses: 1. A polyurethane foam article for surgical use, the foam article comprising a hydrophobic polyurethane foam layer and a hydrophilic/haemophilic polyurethane foam layer, at least one of the layers containing barium sulphate.

2. A polyurethane foam article according to clause 1 wherein the hydrophobic layer contains barium sulphate.

3. A polyurethane foam article according to clause 1 or clause 2, wherein the hydrophobic polyurethane foam layer is made from a polyol and isocyanate composition in which the weight ratio of polyol to isocyanate is from 2:1 to 2.5:1.

4. A polyurethane foam article according to any preceding clause wherein the hydrophobic layer contains 10 to 15% by weight barium sulphate.

5. A polyurethane foam article according to any preceding clause which has an X-ray density eguivalent of from 0.02 to 0.12 gcm of barium sulphate.

6. A polyurethane foam article according to clause 5, which has an X-ray density equivalent of about 0.105 or about 0.035 or about 0.027 gcm of barium sulphate.

7. A polyurethane foam article according to any preceding clause wherein the hydrophilic/haemophilic polyurethane foam layer is made from a polyol and isocyanate composition, in which the weight ratio of polyol to isocyanate is from 1:1 to 1.5:1.

8. A polyurethane foam article according to any preceding clause further comprising an X-ray visible marker such as a sheet, or preferably a tape, which marker includes at least 60% by weight barium sulphate.

9. A polyurethane foam article according to clause 8, wherein the X-ray visible marker is bound between the layers.

10. A polyurethane foam article according any preceding clause, wherein in the polyol and isocyanate composition that forms the hydrophobic polyurethane layer; (i) the polyol comprises 94.8% by weight polyoxyalkylene triols, 1.8% by weight triethanolamine, 0.2% by weight dipropylene glycol, 0.1% by weight triethyldiamine, 0.4% by weight organo-modified polysiloxanes, 2.1% by weight 09-11 alcohol ethoxylate and 0.6% by weight 2-[ [2-dimethylamino)ethyl]methylamino] ethanol, and/or (ii) the isocyanate comprises 50% to 77% by weight diphenylmethanediisocyanate, isomers and homologues thereof, and 23% to 50% by weight isocyanates that are the reaction product of the polyol with methylenediphenyl diisocyanate.

11. A polyurethane foam article according to any preceding clause, wherein in the polyol and isocyanate composition that forms the hydrophilic/haemophilic polyurethane layer; (i) the polyol comprises butane diol, benzenepropanoic acid, 3,5-bis[i, i-dimethylethylj-4-hyroxy-07 branched alkyl esters (wherein 07 is understood to be a carbon backbone having 7 to 9 carbon atoms in it) , glycerine, silicone surfactants and triethylene diamine, and/or (ii) the isocyanate comprises diphenylmethane-4,4-diisocyanate and triphenylphosphite.

12. A polyurethane foam article according any preceding clause, which can be reversibly sgueezed or compressed into a compressed state, wherein liquids are expelled as the article is squeezed or compressed, and liquids are absorbed as the article expands from the compressed state.

13. A polyurethane foam article according to any one of the preceding clauses, having at least one cavity therein, the at least one cavity having a corresponding at least one vent extending to the exterior of the article, the at least one cavity containing an analgesic or haemostatic fluid.

14. A polyurethane foam article, the foam article comprising a hydrophobic polyurethane foam layer and a hydrophiiic/haemophilic polyurethane foam layer, the article having at least one cavity therein, the at least one cavity having a corresponding at least one vent extending to the exterior of the article, the at least one cavity containing an analgesic fluid.

15. A polyurethane foam article according to clause 14, wherein the hydrophobic polyurethane foam layer is made from a polyol and isocyanate composition in which the weight ratio of polyol to isocyanate is from 2:1 to 2.5:1.

16. A polyurethane foam article according to clause 14 or clause 15 wherein the hydrophilic/haemophilic polyurethane foam layer is made from a polyol and isocyanate composition, in which the weight ratio of polyol to isocyanate is from 1:1 to 1.5:1.

17. A polyurethane foam article according to any one of clauses 14 to 16, wherein in the polyol and isocyanate composition that forms the hydrophobic polyurethane layer; (iii) the polyol comprises 94.8% by weight polyoxyalkylene triols, 1.8% by weight triethanolamine, 0.2% by weight dipropylene glycol, 0.1% by weight triethyldiamine, 0.4% by weight organo-modified polysiloxanes, 2.1% by weight C9-11 alcohol ethoxylate and 0.6% by weight 2-[2-dimethylamino)ethyl]methylamino] ethanol, and/or (iv) the isocyanate comprises 50% to 77% by weight diphenylmethanediisocyanate, isomers and homologues thereof, and 23% to 50% by weight isocyanates that are the reaction product of the polyol with methylenediphenyl diisocyanate.

18. A polyurethane foam article according to any one of clauses 14 to 17, wherein in the polyol and isocyanate composition that forms the hydrophilic/haemophilic polyurethane layer; (iii) the poiyoi comprises butane diol, benzenepropanoic acid, 3,5-bis[l, l-dimethylethylj-4-hyroxy-C7 branched alkyl esters (wherein C79 is understood to be a carbon backbone having 7 to 9 carbon atoms in it) , glyoerine, silicone surfactants and triethylene diamine, and/or (iv) the isocyanate comprises diphenylmethane-4,4-diisocyariate and triphenylphosphite.

19. A method of forming a polyurethane foam article comprising two polyurethane foam layers, the method comprising the steps of: (i) disposing a non-polymerised hydrophobic layer comprising a polyol, isocyanate and barium sulphate composition over a hydrophilic/haemophilic layer; and (ii) polymerising the hydrophobic layer; wherein before and/or during the polymerising step, the barium sulphate of the non-polymerised hydrophobic layer partially migrates or egresses into the hydrophilic/haemophilic layer.

20. A method of forming a polyurethane foam article according to clause 13, further comprising the initial step of: (I) positioning an X-ray visible marker on the hydrophilic/haemophilic layer; such that the polymerising step traps the marker and bonds it securely in place.

21. A method of forming a polyurethane foam article comprising two polyurethane foam layers, the method comprising the steps of: (i) disposing a non-polymerised hydrophobic layer comprising a polyol and isocyanate composition over a hydrophilic/haemophilic layer; and (ii) polymerising the hydrophobic layer; wherein the method further includes: forming at least one cavity in the article, the at least one cavity having a corresponding vent extending to the exterior of the article; and Inserting an analgesic fluid into the cavity.

22. A method of forming a polyurethane foam article containing an analgesic fluid, which article comprises a hydrophobic polyurethane foam layer and a hydrophilic/haemophilic polyurethane foam layer, the article having at least one cavity therein, the at least one cavity having a corresponding at least one vent extending to the exterior of the article; wherein the method comprises inserting an analgesic fluid into the cavity.

23. A polyurethane foam article substantially as described herein with reference to, and as illustrated in, the accompanying figures or a method substantially as described herein.

24. A surgical sponge comprising a polyurethane foam article according to any preceding clause.

Claims

CLAIMS1. A polyurethane foam article, the foam article comprising a hydrophobic polyurethane foam layer and a hydrophilic/haemophilic polyurethane foam layer, the article having at least one cavity therein, the at least one cavity having a corresponding at least one vent extending to the exterior of the article, the at least one cavity containing an analgesic fluid.
2. A polyurethane foam article according to claim 1, wherein the hydrophobic polyurethane foam layer is made from a polyol and isocyanate composition in which the weight ratio of polyol to isocyariate is from 2:1 to 2.5:1.
3. A polyurethane foam article according to claim 1 or claim 2 wherein the hydrophilic/haemophilic polyurethane foam layer is made from a polyol and isocyanate composition, in which the weight ratio of polyol to isocyanate is from 1:1 to 1.5:1.
4. A polyurethane foam article according to any one of the preceding claims, wherein in the polyol and isocyanate composition that forms the hydrophobic polyurethane layer; (i) the polyol comprises 94.8% by weight polyoxyalkylene triols, 1.8% by weight triethanolamine, 0.2% by weight dipropylene glycol, 0.1% by weight triethyldiamine, 0.4% by weight organo-modified polysiloxanes, 2.1% by weight C9-ll alcohoi ethoxyiate and 0.6% by weight 2-[ [2-dimethylamino)ethyl]methyiamino] ethanol, and/or (ii) the isocyanate comprises 50% to 77% by weight diphenylmethanediisocyanate, isomers and homologues thereof, and 23% to 50% by weight isocyanates that are the reaction product of the polyol with methylenediphenyl diisocyanate.
5. A polyurethane foam article according to any one of the preceding claims, wherein in the polyol and isocyanate composition that forms the hydrophilic/haemophilic polyurethane layer; (i) the polyol comprises butane diol, benzenepropanoic acid, 3,5-bis[1, 1-dimethyiethyij-4-hyroxy-07 branched alkyi esters (wherein 07 9 is understood to be a carbon backbone having 7 to 9 carbon atoms in it) , glycerine, silicone surfactants and triethylene diamine, and/or (ii) the isocyanate comprises diphenyimethane-4,4-diisocyanate and triphenyiphosphite.
6. A method of forming a polyurethane foam artiole comprising two polyurethane foam layers, the method comprising the steps of (i) disposing a non-polymerised hydrophobic layer comprising a polyol and isocyanate composition over a hydrophilic/haemophilic layer; and (ii) polymerising the hydrophobic layer; wherein the method further includes: forming at least one cavity in the article, the at least one cavity having a corresponding vent extending to the exterior of the article; and inserting an analgesic fluid into the cavity.
7. A method of forming a polyurethane foam article containing an analgesic fluid, which article comprises a hydrophobic polyurethane foam layer and a hydrophilic/haemophilic polyurethane foam layer, the article having at least one cavity therein, the at least one cavity having a corresponding at least one vent extending to the exterior of the article; wherein the method comprises inserting an analgesic fluid into the cavity.A surgical sponge comprising a polyurethane foam article according to any of claims 1 to 5.