Device for measuring liquid viscosity

Abstract

A device for assessing liquid viscosity, comprising a concave reservoir 7 which holds a liquid, which has one or more recesses at the bottom (referred to as wells) 21, 23, 25, 27. Each of these wells

Description

Field of the Invention The invention relates to a device for measuring liquid viscosity wherein said device comprises a concave reservoir configured to hold a volume of liquid and one or more wells extending from an opening disposed at the base of said reservoir, wherein said base comprises an aperture having dimensions configured to retain within said well a liquid having a viscosity at or above a specific threshold viscosity by surface tension, but permit a liquid having a viscosity below said specific threshold viscosity to pass through said well under the influence of gravity. Further, the invention also relates to a method for assessing liquid viscosity using the abovementioned device, particularly in individuals suffering from dysphagia in healthcare facilities, such as care homes. Background of the Invention Dysphagia (difficulties with swallowing) has been associated with high case fatality and poor functional outcomes and puts patients at risk of aspiration, pneumonia, dehydration and malnutrition [1], Dysphagia is a highly prevalent clinical condition that affects up 50% of individuals with stroke [2], 60-80% of individuals with neurodegenerative diseases [3], 10-30% of adults aged 65 years and above [4] and over 51% of institutionalized elderly patients [5]. Current practice in the management of dysphagia frequently involves modification of diet and fluids with patients expected to adopt fluid restriction or change for the course of their dysphagia. Liquids are commonly thickened by adding a commercial thickening agent to the drink in order to increase the consistency of the fluid. Thickening fluids is claimed to reduce aspiration due to these fluids moving more slowly through the oral cavity, thus allowing more time for the individual to trigger a swallow reflex. Additionally, if the laryngeal closure is incomplete during the swallow, it is suggested that thicker viscosities are also less likely to trickle into a person’s airway [6], The degree to which a drink is thickened in order to produce the consistency of fluid which is considered safe for the individual to swallow is determined from an assessment of the nature and severity of the presenting swallowing deficit. In order to address patient safety each drink that the person consumes is thickened to the required consistency. However, guidelines for thickening fluids in care settings are often imprecise with only brief written instructions provided by speech and language therapists (SLTs) and product manufacturers, and these instructions are not always accurately followed by the health workers or carers who prepare drinks for patients. This often results in patients being given drinks that are of a thicker or thinner consistency than is actually required for the individual to swallow safely. Evidence suggests inconsistent making of fluid consistencies across a range of health care professionals and poor inter and intra-rater reliability of fluid consistency production has been reported [7], This lack of consistency may contribute to the patient experiencing medical complications and delayed hospital discharge [8], [9], Following recognition that global agreement on terminology would continue to enhance patient safety and address the number of critical incidents worldwide, the International Dysphagia Diet Standardisation Initiative (IDDSI) was founded in 2013 to develop global standardised definitions to describe texture modified diets and thickened liquids. Figure 1 shows the schematic produced as part of the initiative to aid with the training and understanding of the new descriptors. The initiative breaks food and drinks into eight bands (band zero being an unmodified liquid) with liquids categorised as thin, slightly thick, mildly thick, moderately thick and extremely thick (International Dysphagia Standardisation Initiative, IDDSI, 2019). The IDDSI initiative also proposes that the thickness of the fluid can be determined from a timed gravity flow test using a 10ml syringe. The test requires the syringe to be filled with the thickened liquid and the residual amount in the syringe after 10s determines the thickness level as per the descriptors, i.e. a mildly thick liquid would have a residual fluid level of between 4-8ml and a moderately thick liquid a residual level of between 8-10ml. The test is proposed in this fashion since it uses 'off the shelf' equipment is believed to be user-friendly, inexpensive, easily accessible measurement

[10] , However, despite these improvements, concern had been raised by SLTs and care home staff that whist the IDDSI test claimed was that it was 'cost effective, inexpensive and easy to use', usage in a real care home, hospital or home setting would be inconsistent. This is, in part, due to operational issues, including the propensity for staff to accidentally overfill the syringe and spill the liquid. These problems lead to considerable variability in test preparation time, which is exacerbated by factors such as time pressures for care staff and / or inexperience, as well as a lack of expertise by care givers in the home environment of elderly relatives. The inventors have developed a new method for measuring the viscosity of liquids, providing a portable device that comprises a reservoir connected to a series of wells that permit the flow of liquid into a receptacle. Each well contains an aperture at its base with dimensions configured to reflect the threshold viscosity that define different IDDSI levels. Therefore, the IDDSI level may be ascertained by monitoring the flow of liquid through apertures of increasing cross-sectional dimensions. The present invention, therefore, provides a means of quickly and easily assessing the viscosity of liquids for use in the treatment of patients suffering from dysphagia. Importantly, this device improves upon the current practice by permitting the standardisation of viscosity testing, therefore mitigating the abovementioned problems associated with inconsistency of testing within different settings and among different device operators. Further, the device is easier to operate and quicker to use than the current standard, leading to fewer instances of misuse and, therefore, more precise patient management. Statements of Invention The present invention, in its various aspects, is as set out in the accompanying claims. According to a first aspect, the invention provides a device for assessing liquid viscosity, said device comprising: a. a concave reservoir, configured to hold within said reservoir a volume of liquid; and b. one or more wells extending from an opening disposed at the base of said reservoir and comprising one or more side walls and base, wherein said base comprises an aperture having a depth and cross-sectional dimension(s) configured to retain within said well a liquid having a viscosity at or above a specific threshold viscosity by surface tension, but permit a liquid having a viscosity below said specific threshold viscosity to pass through said well under the influence of gravity. By careful selection of the well dimensions, in particular the depth and cross-sectional dimension(s) of the aperture present within the base, the device can be used to readily identify whether a liquid sample applied to the concave reservoir is of sufficient viscosity to be safely consumed by a patient. In particular, if the liquid sample is retained within the well after a period of time, e.g. from about 5 seconds to about 5 minutes, has passed, one can conclude that the tested liquid is above the viscosity threshold that is specific to the well and, in particular, the aperture dimensions. In contrast, if the liquid has substantially or completely passed through the well via the aperture within this period of time, one can conclude that the tested liquid is at or below the viscosity threshold that is specific to the well. Furthermore, liquid viscosity tests are easily repeatable using the device of the invention, with reliable results obtained in a short amount of time compared to conventional viscosity measurement methods such as the syringe based gravity flow test. As a result, it has been found that the test device is used more regularly to assess the viscosity of nutritional fluids for consumption by given to individuals suffering from dysphagia, particularly in pressurized and time sensitive healthcare facilities such as care homes. Such an increase in compliance with patient specific fluid thickening and viscosity testing will reduce the risk of choking and aspiration for dysphagic individuals, and ultimately save lives. The size of the device is not particularly limited and can vary depending on the volume of liquid the user wishes to apply in order to test the viscosity of any given sample. However, in a preferred embodiment, said reservoir is configured to hold a volume of liquid of at least about 2.5 mL, and more preferably from about 2.5 mL to about 10 mL. In an exemplary embodiment, the reservoir is configured to hold a volume of about 5 mL, i.e., equivalent to a teaspoon of liquid. Such a volume has been found to be sufficient to achieve a reliable result without wasting sample fluid. The dimensions of the wells are not particularly limited, provided that they are of appropriate size considering the volume of sample fluid to be added. However, in preferred embodiments, each of said one or more wells has a cross-sectional area of at least about 20 mm2, more preferably at least about 30 mm2, still more preferably at least about 40 mm2. Alternatively, or additionally, in preferred embodiments, each of said one or more wells has a cross-sectional area of no more than about 200 mm2, more preferably about 150 mm2 and still more preferably about 125 mm2. In an exemplary embodiment, the cross-sectional area is configured to be about 50 mm2. As the skilled reader will readily appreciate, the wells must have a sufficient depth to hold a volume of liquid that is easily observable by eye. Therefore, in preferred embodiments, each of said wells has a depth of at least about 2 mm, more preferably at least about 3 mm and still more preferably at least about 4 mm. Alternatively, or additionally, each of said wells preferably has a depth of no more than about 10 mm, more preferably about 8 mm and still more preferably about 6 mm. In an exemplary embodiment, each of said wells has a depth of about 5 mm. Each of said wells has an aperture at its base through which fluid can pass under the influence of gravity. As will be appreciated, the dimensions of the aperture primarily dictate whether a liquid of any given thickness is able to pass through or is retained within the well. Further, if the liquid is retained within the well, one can conclude that the tested liquid is too thick to pass through the aperture, whereas if no appreciable liquid remains in the well after a specified period of time, e.g. from about 5 seconds to about 5 minutes, has passed, one can conclude that the tested liquid is at or below the well specific viscosity threshold. For example, if liquid is retained within a well configured to permit liquids of a thickness approximately equivalent to IDDSI Level 2 to pass through it, the tested liquid would have a thickness of at least IDDSI Level 3. However, if the liquid has passed through the well within the specified test period, the tested liquid has a thickness of no more than IDDSI Level 2. In preferred embodiments, the outlet, i.e. the end distal to the well, of each of said apertures is counterbored and so are recessed within the main body of the base. The provision of such an enlarged outlet significantly reduces surface tension at the aperture exit, and so enables more uniform liquid flow. It is within the skilled persons remit to configure appropriate aperture dimensions, i.e. cross-sectional radius and depth that will allow liquid of any specified thickness to pass. However, it has been found that apertures, typically cylindrical apertures, having a cross-sectional diameter of from about 0.5 mm to about 6 mm and / or a depth of from about 5 mm to about 15 mm are suitable for the intended use. It has been found that, by varying the cross sectional profile and / or depth within these specified ranges, wells can be specifically designed to allow fluids having a thickness equivalent to Level 4, Level 3, Level 2, or Level 1 on the IDDSI framework to pass through. Such apertures may be of substantially uniform profile along their length, and may or may not comprise an enlarged, counterbored, outlet. However, said apertures may have a shallow taper (e.g. about 2 degrees or less) to facilitate production of the device. In such embodiments, the specified aperture dimension is measured distal to the well, before any enlarged, counterbored, outlet. For example, the cross-sectional profile of cylindrical apertures having a depth of about 12 mm can be configured to only allow liquids of a thickness equivalent to a specific IDDSI Level to pass. In particular, a cylindrical aperture having a cross-sectional radius of 0.8 mm allows IDDSI Level 1 (slightly thick) liquids to pass. Similarly, cylindrical apertures having a cross-sectional radius of 1.3 mm, 3 mm, and 5.5 mm allow IDDSI Level 2 (mildly thick), IDDSI Level 3 (moderately thick), IDDSI Level 4 (extremely thick) liquids to pass, respectively. However, it would be readily appreciated that alternative configurations could equally be used. For example, if the aperture depth is increased, the cross-sectional area may be reduced to provide similar viscosity threshold. The device may comprise one or more wells. As will be appreciated, a device comprising a single well is suitable for determining whether a tested liquid is at or below a target viscosity. However, a device comprising a plurality of wells can be used to determine with more accuracy the actual viscosity of the tested liquid, provided that each of said wells comprises an aperture having a depth and cross-sectional dimensions that is configured to only retain a liquid having viscosity at or above a different specific threshold viscosity to each other member of said plurality of wells. For example, noting that the IDDSI system characterises liquid thickness into four distinct categories, said base may preferably comprise four wells, wherein the first well comprises an aperture having a cross sectional area and depth configured to only retain a liquid having a viscosity at or above a specific threshold viscosity approximately equivalent to IDDSI level of 1 (slightly thick); the second well comprises an aperture having a cross sectional area and depth configured to only retain a liquid having a specific viscosity at or above a threshold viscosity approximately equivalent to IDDSI level of 2 (mildly thick); the third well comprises an aperture having a cross sectional area and depth configured to only retain a liquid having a specific viscosity at or above a threshold viscosity approximately equivalent to IDDSI level of 3 (moderately thick); and the fourth well comprises an aperture having a cross sectional area and depth configured to only retain a liquid having a specific viscosity at or above a threshold viscosity approximately equivalent to IDDSI level of 4 (extremely thick). Where a device comprises a plurality of wells, each of said wells can be provided at the base of a single reservoir. However, in an alternative embodiment, said device is a modular device comprising a plurality of vertically stackable modules, wherein each of the plurality of modules comprises a reservoir comprising a single well having an aperture having a depth and cross-sectional dimension(s) configured to only retain a liquid having a viscosity at or above a different specific threshold viscosity. For example, the device may comprise four removably stackable modules, wherein: the first module comprises a first well having an aperture having a depth and cross-sectional area configured to only retain a liquid having a viscosity at or above a specific threshold viscosity approximately equivalent to IDDSI level of 4 (extremely thick); the second module comprises a first well having an aperture having a depth and cross-sectional area configured to only retain a liquid having a viscosity at or above a specific threshold viscosity approximately equivalent to IDDSI level of 3 (moderately thick); the third module comprises a first well having an aperture having a depth and cross-sectional area configured to only retain a liquid having a viscosity at or above a specific threshold viscosity approximately equivalent to IDDSI level of 2 (mildly thick); and the fourth module comprises a first well having an aperture having a depth and cross-sectional area configured to only retain a liquid having a viscosity at or above a specific threshold viscosity approximately equivalent to IDDSI level of 1 (slightly thick), wherein, in use, said modules are configured in a vertically stacked orientation such that the first module is disposed above the second module, the second module is disposed above the third module, and the third module is disposed above the fourth module. As will be appreciated, the modular device may contain less than four such modules, or less than four of said modules may be used at any given time. The device is manufactured from any suitable material, e.g., plastic or metal. However, in preferred embodiments, the device is made from a plastic, more preferably a food- and dishwasher-safe plastic material. Typical examples of such food grade and dishwasher-safe plastics include any bisphenol A (‘BPA’) free thermoset or thermoplastic material having a glass transition temperature of at least 70°C. Many such food grade and dishwasher safe plastics are commercially available, including but not limited to high density polyethylene (HDPE), low density polyethylene (LDPE) and polypropylene (PP). In use, the device is typically placed over a fluid collection device, such as a cup or a mug. Therefore, in a preferred embodiment, said device comprises an optionally removable support member, wherein said support member is configured to secure the concave reservoir(s) in an upright position above a fluid collection device such as a cup or mug. Clearly the use of such a support member makes the device hands-free. The device is configured to assess the viscosity of thickened liquids, particularly in healthcare environments. Therefore, according to a second aspect, the invention provides a method for assessing the viscosity of a liquid, the method comprising: a. providing a device according to the first aspect of the invention; b. adding a volume of liquid to be assessed on to the concave reservoir; c. allowing a period of time for said liquid to pass through said device; d. observing whether said liquid has been retained within any or all of said wells; and e. where said liquid is observed to have been retained in any member of said one or more wells, concluding that said liquid is at or before the specific threshold viscosity of said well, or where said liquid is observed to have passed through any member of said or more wells, concluding that said liquid is below the specific threshold of said well. Preferably, in step c., said period of time is at least about 5 seconds, more preferably, at least about 15 seconds, still more preferably at least about 30 seconds. Alternatively, or additionally, said period of time is preferably no more than about 5 minutes, more preferably no more than about 3 minutes, still more preferably no more than about 1 minute. According to a third aspect, the invention provides a method for assessing the viscosity of a liquid, the method comprising: a. providing a modular device according to the first aspect of the invention; b. stacking at least two and optionally all of said modules in a vertical arrangement in numerical order based on aperture size, with the module comprising the largest sized aperture disposed at the top of the stack and the module comprising the smallest sized aperture disposed at the bottom of the stack; c. adding a volume of liquid to be assessed to the concave reservoir of the module disposed at the top of the stack; d. allowing a period of time for said liquid to pass through all of said modules; e. observing whether the liquid has been retained within any of said modules; and f. where said liquid is observed to have been retained in the well of any of said modules, concluding that said liquid is at or before the specific threshold viscosity of said well, or where said liquid is observed to have been in contact with but has subsequently passed through the well of any such modules, concluding that said liquid is below the specific threshold of said well. Preferably, in step d., said period of time is at least about 5 seconds, more preferably, at least about 15 seconds, still more preferably at least about 30 seconds. Alternatively, or additionally, said period of time is preferably no more than about 5 minutes, more preferably no more than about 3 minutes, still more preferably no more than about 1 minute. In preferred embodiments of the first, second and third aspects, said liquid is intended for introduction into a mammalian, preferably a human, body. In particular, said liquid is intended for oral consumption, and preferably for oral consumption by an individual with swallowing difficulties, for example, patients with dysphagia. According to a fourth aspect, the invention provides for the use of the device according to the first aspect for assessing the viscosity of nutritional liquid. In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word “comprises”, or variations such as “comprise” or “comprising” is used in an inclusive sense i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise. Throughout the description and claims of this specification, the term “about” includes a variation of ± 5%, preferably ± 4%, more preferably ± 3%, still more preferably ± 2% and most preferably ± 1% unless the context otherwise requires. For the purpose of the application, the terms viscosity and thickness are used interchangeably. Preferred features of each aspect of the invention may be as described in connection with any of the other aspects. Other features of the present invention will become apparent from the following examples. Generally speaking, the invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including the accompanying claims and drawings). Thus, features, integers, characteristics or compounds described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein, unless incompatible therewith. Moreover, unless stated otherwise, any feature disclosed herein may be replaced by an alternative feature serving the same or a similar purpose. Any references, including any patent or patent application, cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. Further, no admission is made that any of the prior art constitutes part of the common general knowledge in the art. Embodiments of the invention will now be described by way of example only with reference to the following figures where: Figure 1 provides a schematic representation of the IDDSI thickness framework (source IDDSI.org) routinely used to assess the texture and viscosity of foods and thickened liquids for people with dysphagia; Figure 2 provides a perspective view of the viscosity assessment device according to the first aspect of the invention; Figures 3(A) and 3(B) provide perspective views of the main body component of the viscosity assessment device shown in Figure 1; Figure 4 provides a perspective view of the viscosity assessment device according to the first aspect of the invention, wherein the main body and support member components are formed as separate components; Figure 5 provides a schematic representation, showing internal features, of the main body component of the viscosity assessment device shown in Figure 1; and Figure 6 provides a bottom view of the main body component of the viscosity assessment device shown in Figure 1. Referring firstly to Figure 2, a perspective view of an embodiment of the device of for assessing liquid viscosity is shown. The device 1 is formed from two parts, a main body 3 and a removable support member 5, each of which are formed from a food- and dishwasher-safe thermoset polypropylene. However, as will be readily appreciated, the main body 3 and support member 5 may be made from a wide variety of suitable materials, in particular a metal or BPA-free plastic. The main body 3 and support member 5 are shown separately in Figure 3 and Figure 4, respectively. The main body 3 comprises a concave reservoir 7, which is appropriately dimensioned to receive and hold at least 5 mL, i.e. the equivalent of a single teaspoon, of a liquid to be tested. In addition, a first well 21, second well 23, third well 25 and a fourth well 27, each of which has a depth of about 5 mm and cross sectional area of about 50 mm2, extends downwards from the base of the reservoir 7. Further, cylindrical apertures 31, 33, 35, 37, each having a depth of about 12 mm, are located at the base of said wells 21, 23, 25, 27. Notably, and as shown most clearly in Figure 5 and Figure 6, the cross sectional radius of each aperture is different, with the cross sectional radius increasing from the first aperture 31, the second aperture 33, the third aperture 35 and the fourth aperture 37. As will be appreciated, by providing a series of wells comprising apertures of increasing cross sectional diameter, one is able to accurately assess the viscosity of a test liquid applied onto the surface of the reservoir 7. In particular, in a preferred embodiment the first aperture 31 has a cross sectional radius of about 0.8 mm, the second aperture 33 has a cross sectional radius of about 1.3 mm, the third aperture 35 has a cross sectional radius of about 3 mm, and the fourth aperture 37 has a cross sectional radius of about 5.5 mm, and so permit liquids of viscosity approximately equivalent to IDDSI level 1 (slightly thick), IDDSI level 2 (mildly thick), IDDSI level 3 (moderately thick), and IDDSI level 4 (extremely thick) to pass, respectively. As will be appreciated, the apertures 31, 33, 35, 37, are of substantially uniform profile along their length. However, as best shown in Figure 5 and Figure 6, each aperture 31, 33, 35, 37 is provided with a counterbored, i.e. enlarged and recessed within the main body 3, fluid outlet 41, 43, 45, 47, which reduces surface tension at the aperture exit, thus enabling a more uniform liquid flow. In use, the main body 3 is typically placed vertically above a fluid collection device, typically a cup or mug, prior to application of a liquid sample to the concave reservoir 7. Therefore, liquid that passes through any of wells 21, 23, 25, 27 through apertures 31, 33, 35, 37 will be recovered in the collection device without spillage. Therefore, the main body is preferably used in conjunction with a support member 5, which may be formed as a separate component to body 3 (as best shown in Figure 4) or, alternatively, support member 5 and body 3 may be provide as a single integrated component. As shown in Figure 2 and Figure 4, the support member 5 is a thin adapter that has sufficient length in at least one dimension to engage with the rim of, and so sit securely above, a cup or mug. In addition, the support member 5 comprises a hole 9, which is appropriately dimensioned to accept and securely hold the body 3 in an upright position directly above the fluid collection device. The device is small, lightweight and portable, and so can be carried by, e.g., healthcare professionals without difficulty. Moreover, when there is a need to assess the viscosity of a thickened liquid, e.g. when a dysphagic patient requires a nutritional fluid to be at or above a particular IDSII framework viscosity, the device 1 can be simply placed above a cup or mug, and approximately 5 ml (i.e. a tea spoon) of the thickened liquid added on to the reservoir 7 and left to pass into and / or through the wells 21, 23, 25, 27 under the influence of gravity for a period of time (e.g. from 5 seconds to 5 minutes). Then, once the allotted time has passed, the thickness of the tested liquid can be determined by assessing within which wells the test liquid has passed through. For example, if it is found that the tested liquid has been retained in the first well 21 and the second well 23, but has passed through both the third well 25 and fourth well 27, one can conclude that the thickness of the tested liquid was (i) greater than IDDSI level 1; (ii) greater than IDDSI level 2; (iii) at or below IDDSI level 3; and (iv) at or below IDDSI level 4. Therefore, based on these findings in totality, one can conclude that the tested sample was of a thickness equivalent to IDDSI level 3 (moderately thick). References [1] Warlow, C., van Gijn, J., Dennis, M., Wardlaw, J., Bamford, J., Hankey, G. J., Sandercock, P., Rinkel, G., Langhorne, P., Sudlow, 0., &Rothwell, P. 2008, Stroke Practical Management, 3rd edn, Blackwell Publishing.Philip Bath Syst review. [2] Singh, S. &Hamdy, S, 2006, Dysphagia in Stroke Patients. Postgrad Med J. Jun; 82(968): 383-391. [3] Horner, J., Alberts, M. J., Dawson, D. V., &Cook, G. M., 1994, Swallowing in Alzheimer's disease. Alzheimer disease and associated disorders, 8(3), 177-189. [4] Barczi SR, Sullivan PA, Robbins J. How should dysphagia care of older adults differ? Establishing optimal practice patterns. Semin Speech Lang. 2000;21:347-61. [5] Kayser-Jones K, Pengilly K. Dysphagia among nursing home residents. Geriatr Nurs. 1999;20:77-84. [6] Logemann, J.A. The evaluation and treatment of swallowing disorders (1998) Current Opinion in Otolaryngology and Head and Neck Surgery, 6 (6), pp. 395-400. [7] Chichero, J., Clave, P. Stepping stones to living well with dysphagia: 72nd nestle nutrition institute workshop, Barcelona, May, 2011: Comment (2013) Dysphagia, 28 (4), p. 593. [8] Finestone, H.M., Foley, N.C., Woodbury, M.Gail, Greene-Finestone, L. Quantifying fluid intake in dysphagic stroke patients: A preliminary comparison of oral and nonoral strategies (2001) Archives of Physical Medicine and Rehabilitation, 82 (12), pp. 1744-1746. [9] Crary MA, Groher ME. Introduction to Adult Swallowing Disorders. Philadelphia, PA: Butterworth Heinemann; 2003

[10] Cichero, J.A.Y., Lam, P., Steele, C.M., Hanson, B., Chen, J., Dantas, R.O., Duivestein, J., Kayashita, J., Lecko, C., Murray, J., Pillay, M., Riquelme, L., Stanschus, S. Development of International Terminology and Definitions for Texture-Modified Foods and Thickened Fluids Used in Dysphagia Management: The IDDSI Framework (2017) Dysphagia, 32 (2), pp. 293-314.

Claims

1. A device for assessing liquid viscosity, said device comprising:a. a concave reservoir, configured to hold within said reservoir a volume of liquid; andb. one or more wells extending from an opening disposed at the base of said reservoir and comprising one or more side walls and base,wherein said base comprises an aperture having a depth and cross-sectional dimension(s) configured to retain within said well a liquid having a viscosity at or above a specific threshold viscosity by surface tension, but permit a liquid having a viscosity below said specific threshold viscosity to pass through said well under the influence of gravity.

2. The device according to claim 1, wherein said reservoir is configured to hold a volume of liquid of between about 2.5 mL and about 10 mL.

3. The device according to claim 1 or claim 2, wherein each of said one or more wells has a cross-sectional area of from about 20 mm2 to about 200 mm2.

4. The device according to any of the preceding claims, wherein each of said one or more wells comprises one or more side walls and a base that together define a well having a depth of from about 2 mm to about 10 mm.

5. The device according to any of the preceding claims, wherein each of said one or more wells comprises an aperture having a depth and cross-sectional dimensions configured to only retain within said well a liquid having a viscosity at or above a specific threshold viscosity approximately equivalent to IDDSI level 1 (slightly thick), IDDSI level 2 (mildly thick), IDDSI level 3 (moderately thick) and IDDSI level 4 (extremely thick).

6. The device according to any of the preceding claims, wherein each of said one or more wells comprises a cylindrical aperture having a cross-sectional radius of from about 0.5 mm2 to about 6 mm2.

7. The device according to any of the preceding claims, wherein each of said one or more wells comprises an aperture having a depth of from about 5 mm to about 15 mm.

8. The device according to claim 5, wherein each of said wells comprises a cylindrical aperture having a depth of about 12 mm and a cross section radius selected from: about 0.8 mm (IDDSI Level 1 (slightly thick)); about 1.3 mm (IDDSI Level 2 (mildly thick)); about 3 mm (IDDSI Level 3 (moderately thick)); and about 5.5 mm (IDDSI Level 4 (extremely thick)).

9. The device according to any of the preceding claims, wherein the distal end of said aperture(s) are counterbored.

10. The device according to any of the preceding claims, wherein said device is a food-and dishwasher-safe plastic material.

11. The device according to any of the preceding claims, wherein said base comprises a plurality of wells, and wherein each member of said plurality of wells comprises an aperture having a depth and cross-sectional dimensions configured to only retain a liquid having viscosity at or above a different specific threshold viscosity to each other member of said plurality of wells.

12. The device according to claim 11, wherein said base comprises four wells, and wherein:the first well comprises an aperture having a cross sectional area and depth configured to only retain a liquid having a viscosity at or above a specific threshold viscosity approximately equivalent to IDDSI level of 1 (slightly thick);the second well comprises an aperture having a cross sectional area and depth configured to only retain a liquid having a specific viscosity at or above a threshold viscosity approximately equivalent to IDDSI level of 2 (mildly thick);the third well comprises an aperture having a cross sectional area and depth configured to only retain a liquid having a specific viscosity at or above a threshold viscosity approximately equivalent to IDDSI level of 3 (moderately thick); andthe fourth well comprises an aperture having a cross sectional area and depth configured to only retain a liquid having a specific viscosity at or above a threshold viscosity approximately equivalent to IDDSI level of 4 (extremely thick).

13. The device according to any of claims 1 to 12, wherein said device is a modular device comprising a plurality of vertically stackable modules, characterised in that each of the plurality of modules comprises a reservoir comprising a single well having an aperture having a depth and cross-sectional dimension(s) configured to only retain a liquid having a viscosity at or above a different specific threshold viscosity.

14. The device according to claim 13, wherein said device comprises four removably stackable modules, and wherein:the first module comprises a first well having an aperture having a depth and cross-sectional area configured to only retain a liquid having a viscosity at or above a specific threshold viscosity approximately equivalent to IDDSI level of 4 (extremely thick);the second module comprises a first well having an aperture having a depth and cross-sectional area configured to only retain a liquid having a viscosity at or above a specific threshold viscosity approximately equivalent to IDDSI level of 3 (moderately thick);the third module comprises a first well having an aperture having a depth and cross-sectional area configured to only retain a liquid having a viscosity at or above a specific threshold viscosity approximately equivalent to IDDSI level of 2 (mildly thick); andthe fourth module comprises a first well having an aperture having a depth and cross-sectional area configured to only retain a liquid having a viscosity at or above a specific threshold viscosity approximately equivalent to IDDSI level of 1 (slightly thick), wherein, in use, said modules are configured in a vertically stacked orientation such that the first module is disposed above the second module, the second module is disposed above the third module, and the third module is disposed above the fourth module.

15. The device according to any of the preceding claims, further comprising an optionally removable support member.

16. The device according to claim 15, wherein said support member is configured to secure the concave reservoir(s) in an upright position above a fluid collection device such as a cup or mug.

17. A method for assessing the viscosity of a liquid, the method comprising:a. providing a device according to any of claims 1 to 12, 15 or 16;b. adding a volume of liquid to be assessed on to the concave reservoir;c. allowing a period of time for said liquid to pass through said device;d. observing whether said liquid has been retained within any or all of said wells; ande. where said liquid is observed to have been retained in any member of said one or more wells, concluding that said liquid is at or before the specific threshold viscosity of said well, or where said liquid is observed to have passed through any member of said or more wells, concluding that said liquid is below the specific threshold of said well.

18. A method for assessing the viscosity of a liquid, the method comprising:a. providing a modular device according to any of claims 13 to 16;b. stacking at least two and optionally all of said modules in a vertical arrangement in numerical order based on aperture size, with the module comprising the largest sized aperture disposed at the top of the stack and the module comprising the smallest sized aperture disposed at the bottom of the stack;c. adding a volume of liquid to be assessed to the concave reservoir of the module disposed at the top of the stack;d. allowing a period of time for said liquid to pass through all of said modules;e. observing whether the liquid has been retained within any of said modules; andf. where said liquid is observed to have been retained in the well of any of said modules, concluding that said liquid is at or before the specific threshold viscosity of said well, or where said liquid is observed to have been in contact with but has subsequently passed through the well of any such modules, concluding that said liquid is below the specific threshold of said well.

19. The method according to claim 17 or claim 18, wherein said liquid is intended for introduction into a mammalian, preferably a human, body.

20. The method according to claim 19, wherein said liquid is intended for oral consumption, and preferably for oral consumption by an individual with dysphagia.

21. Use of the device according to any of claims 1 to 16 for assessing the viscosity of a nutritional liquid.

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