Understanding the World of Viscosity: A Tutorial on Rheology

Transcription

1 Understanding the World of Viscosity: A Tutorial on Rheology Catriona M. Steele, Ph.D., CCC Jane Mertz Garcia, Ph.D., CCC Russell H. Mills, Ph.D., CCC-SLP, BRS Ph.D., CCC-SLP, S-LP(C) S Ph.D., CCC-SLP SLP, BRS-S, S, FASHA ASHA Convention 28. Chicago, IL. Outline History of texture modification: What does the literature say? (Steele) Current practice patterns with respect to texture modification (Garcia) Standards, Terminology and Limitations in our knowledge (the honesty piece) (Mills) Rheology: Definitions (Steele) Factors that influence viscosity (Garcia) Application to Clinical Practice (Mills) History of texture modification (Steele)? What is the physiological impact of texture modification 1

2 The effects of viscosity on swallowing: Lof,, G. L., & Robbins, J. (199). Test-retest variability in normal swallowing. Dysphagia, 4, greater variability for 7 of 9 duration variables for paste-consistency compared to liquid barium swallows The effects of viscosity on swallowing: Lazarus, C. L., Logemann, J. A., Rademaker, A. W., Kahrilas, P. J., Pajak,, T., Lazar, R., et al. (1993). Effects of bolus volume, viscosity, and repeated swallows in nonstroke subjects and stroke patients. Archives of Physical Medicine and Rehabilitation Arch.Phys.Med.Rehabil, 74(1), longer durations of tongue-base to posterior pharyngeal wall contact and of P-E E segment opening for paste- consistency compared to liquid barium swallows The effects of viscosity on swallowing: Miller, J. L. (1993). The influence of volume and viscosity on the distribution of anterior lingual force during oral stage swallowing. Unpublished Masters, McGill University, Montreal. higher peak force in tongue for high viscosity (pudding, applesauce) versus low (water) THIN 2

3 The effects of viscosity on swallowing: Pouderoux,, P., & Kahrilas, P. J. (1995). Deglutitive tongue force modulation by volition, volume, and viscosity in humans. Gastroenterology., 18(5), ml boluses of pudding and mashed potato elicited higher amplitudes and later onset of tongue base peak pressure than 3 ml boluses of water; peak pressures were significantly higher for mashed potato than for pudding THIN? SOFT SOLID The effects of viscosity on swallowing: Nicosia, M. A., Hind, J. A., Roecker, E. B., Carnes, M., Doyle, J., Dengel,, G. A., et al. (2). Age effects on the temporal evolution of isometric and swallowing pressure. Journals of Gerontology Series A-Biological A Sciences & Medical Sciences., 55(11), M Higher lingual pressures observed for 3 ml semi solid bolus (esophacat( esophacat) compared to 3 ml and 1 ml liquid (thin barium) boluses The effects of viscosity on swallowing: Perlman, A. L., Vandaele,, D. J., & Otterbacher, M. S. (1995). Quantitative assessment of hyoid bone displacement from video images during swallowing. J Speech Hear.Res., 38(3), Larger hyoid movements for paste vs. thin liquid barium stimuli 3

4 The effects of viscosity on swallowing: Swallowing frequency (swallows per second) was reduced for thicker items (? longer transit times) A trend towards greater variability in the amplitude and duration of downward tongue dorsum movement was seen with thicker consistencies (honey-thick vs. thinner items) THIN & Texture Modification Steele, C. M., & Van Lieshout, P. H. (24). Influence of bolus consistency on lingual behaviors in sequential swallowing. Dysphagia, 19(3), Logemann, J. A., Gensler,, G., Robbins, J., Lindblad, A. S., Brandt, D., Hind, J. A., Kosek,, S., Dikeman,, K., Kazandjian,, M., Gramigna,, G. D., Lundy, D., McGarvey- Toler, S. & Miller Gardner, P. (28). A Randomized Study of Three Interventions for Aspiration of Thin Liquids in Patients with Dementia or Parkinson s s Disease (aka( Protocol 21). Protocol 21 Part 1: Studied immediate (compensatory) effect of chin-tuck, nectar-thick thick liquid and honey-thick liquid on aspiration in videofluoroscopy. Part 2: Studied incidence of pneumonia over 3 months in patients randomized to either chin-tuck, nectar-thick thick liquid or honey-thick liquids. 4

5 Protocol 21, Part 1: 711 participants with usable data, 7% male 59% aged 8 or older Diagnoses: Dementia (49%), Parkinson s s disease (32%), both (19%) Participants declined option of enteral feeding before study Eligibility criterion in VFSS: aspiration on at least 1 thin liquid swallow (three 3-ml 3 sips, 3 cup sips) Interventions tested in random order: Chin tuck with thin liquid Nectar-thick thick liquid Honey-thick liquid Aspiration resolved by ALL 3 interventions: 25% overall (32% PD, 2% Dementia, 26% both) Aspiration continued with ALL 3 interventions: 49% overall (39% PD, 55% Dementia, 5% both) 26% with preferential response discharged with that recommendation Protocol 21, Part 2: 177 participants who did not aspirate with ANY of the 3 Part I interventions, PLUS 348 participants who aspirated regardless of the 3 Part I interventions Randomized to: Chin Tuck (with thin liquids) N = 259 Thickened Liquid N = 256 Nectar: N= 123 Honey: N=126 Measured occurrence of pneumonia over 3 months, defined as evidence of pneumonia on chest x-ray, x OR 3 or more of: Sustained febrile illness >1 F Presence rales or rhonchi Positive Sputum grams stain Positive Sputum culture 5

6 Protocol 21, Part 2: The 3-month 3 incidence of pneumonia did not differ significantly between patients randomized to chin down posture and those randomized to thickened liquids (nectar, honey) Within the group randomized to thickened liquids, the probability of developing pneumonia was significantly higher in those receiving the honey-thick liquids. Are we hypersensitive to the fact that our patients may aspirate? John R. Ashford. PhD Tennessee State University, Nashville, TN (Dissertation 1999, Vanderbilt University) 6

7 NUTRITION Patients with CVA (1%) 43-54% Aspirators 46-57% Nonaspirators 37% Pneumonia 63% No Pneumonia 3.7% Omega Veterans Health Administration Directive 26-32; May 17, 26 RBC INDICES HYDRATION ORAL PHARY NGEAL ESOPHA GEAL INFECTION IMMUNE SYS RENAL C RH Mills 25 Understanding practice patterns is important Asha 27 Survey of Health Care SLPS 7

8 Survey of Practice Patterns On-line survey of DIV 13 members 145 SLPs responded Highly experienced (48% with 1 or more years of dysphagia management) Primarily served adults Acute/Subacute 68% Outpatient 57% Rehabilitation 37% SNF 35% Garcia, J. M., Chambers IV, E., & Molander, M. (25). Thickened liquids: Practice patterns of speech-language pathologists. American Journal of Speech-Language Pathology, 14, Do SLPs support the use of thickened liquids? 1% 9% 8% 7% 6% 5% 4% 3% 2% 1% % 85% Yes No Other How frequently are liquid modifications recommended? 24% 11% 7% 4% No Response < 5% 15% 6-15% 16-25% 26-5% 51-75% 13% 76-9% >9% 26% Half of SLPs prescribe thickened liquids for ¼ to ¾ of patients with impaired swallowing 8

9 What are typical levels of modification? Most thicken to nectar-like consistency (72% of respondents) Estimated percent of patients at each level of modification 64% nectar-thick thick 31% honey-like 5% spoon-thick What are SLP perceptions about patients attitudes? Spoon-thick Honey Nectar Strong liking Strong disliking Neither likes nor dislikes Half like & half dislike Liking relates to product Other No response % 1% 2% 3% 4% 5% Does a patient s s attitude about thickened liquids change over time? Yes, it improves No, it doesn t t change Yes, it worsens No response 21.5% 27.5% 32.9% 18.1% About 6% felt that initial attitudes did not change or attitudes actually worsened 9

10 What types of thickening products? Prethickened 33.8% Products that require preparation 33.1% Combination approach 2% What is the decision-making process for production selection? No Response 12% Patient Preference 7% Other 12% Cost 17% Ease of Preparation 5% Don't Know 38% SLP role in product selection appeared limited Service delivery Who is responsible for their preparation? No one profession Usually not the SLP, patient or family member Are staff formally instructed in their preparation? Only 44.9% indicated that their facility routinely did so Varied training procedures 1

11 Practice patterns reflect High percentage of SLPs value thickened liquids as a management strategy Nectar-modification is most common Prescribed for ¼ to ¾ of patients with dysphagia in some settings Patients do not like thickened liquids Less than ½ of SLPs provide staff instruction about preparation SLPs have limited involvement in product selection Standards, Terminology and Limitations (Mills) National Dysphagia Diet Task Force Sanctioned by ADA, but not by ASHA. An initial step in standardization of diets. Provided nomenclature and viscosity ranges for liquids. Provided diet nomenclature, levels and component foods. Final document released as an ADA publication in 22. Criticized as a consensus document. 11

12 Viscosity Label Distributions Subjects Responding Thin Nectar Honey SpoonTK Brown, MS, Mills, RH, Daubert, CR and Casper, MA, Establishing Labels and Standards for Thickened Liquids in the Dysphagia Diet, Consultant Dietitian, 23:2, 1998, pp 1-5. Number of Unique Labels Distribution of Viscosity Labels Viscosity Levels Brown, MS, Mills, RH, Daubert, CR and Casper, MA, Establishing Labels and Standards for Thickened Liquids in the Dysphagia Diet, Consultant Dietitian, 23:2, 1998, pp 1-5. (t=-4.195; p=.23) SLPs RDs National Dysphagia Diet (USA) Liquid Viscosities: Thin: 1-5 cp Nectar-Like: cp Honey-Like: cp SR = 5 -s Food Textures: Level 1: Dysphagia Pureed Level 2: Dysphagia Mechanically Altered Level 3: Dysphagia Advanced 12

13 National Dysphagia Diet Food Texture Parameters Compression: deformation of food as force is applied (marshmallow) Adhesiveness: food is attracted to another surface (peanut butter) Tensile: food is extended or elongated due to the force applied. Shear: food is cut into pieces by forces that are not directly opposing resulting in a shredding action. Fracture: food is broken by two directly opposing forces (a crispy cracker bitten between the incisors). Veteran s s Dysphagia Diet (USA) An effort of the VA Nutrition & Food Service Speech-Language Pathologist Task Force Originally planned for four Diet Textures System-wide Production Problems were encountered VDD now mirrors NDD 13

14 Australia North America (NDD) Nectar-thick Fluids ( s-1 ) Honey-thick Fluids ( s-1 ) Spoon-thick Fluids (>175 5 s-1 ) REMEMBER: Standard terminology is a worthy goal BUT All standardized labeling conventions to date are PERCEPTION- BASED and SUBJECTIVE Science Driven Standards? National Dysphagia Diet USA (22) Fluid Standards Texture Standards Consensus Driven Consensus Driven Australian Standards for Texture Modified Foods & Fluids (27) Fluid Standards Consensus Driven Texture Standards Consensus Driven National Veteran s s Dysphagia Diet (28) Fluid Standards Texture Standards Consensus Driven Consensus Driven Rheology: Definitions (Steele) 14

15 What is Viscosity? Viscosity = resistance of a substance to flow under an applied force Rheograms for Newtonian Liquids Non-Newtonian Newtonian Liquids 15

16 From Steffe, J.F. (1996). Rheological methods in food process engineering. Available online: Freeman Press: East Lansing, MI. What Influences or Determines Fluid Viscosity? ph and chemical composition Solids content Temperature Time Amount of force applied (shear stress) Rate at which shear force is applied Wall-slip (saliva and mucosal conditions) What Other Fluid Characteristics Might Influence Swallowing? Consistency: a quality that is perceptible to touch Density: the mass (weight) per unit of volume Yield Stress: the amount of force required to initiate liquid flow 16

17 Rotational spindle viscometer Falling weight viscometer Cone-plate viscometer Cone-Plate Viscometry 17

18 Line Spread Test Budke, J., Garcia, J. M., & Chambers IV, E. (28). Comparisons of thickened beverages using line spread measurements. Journal of the American Dietetic Association, 18, Sample line spread with thickened orange juice Nectar-like Honey-like Repeatable Measurements Nectar Honey 8 7 Line Spread Value Water OJ Milk Water OJ Milk Thicken Up Thick & Easy Differentiated products/beverages Flow distances correlated to some extent with viscometer measurements 18

19 Factors that influence viscosity Thickener composition (starch vs. gum) Base liquid Setting time to thicken Serving temperature Instant (requires preparation) vs. Prethickened products Process of Thickening Similarity swelling process to thicken Differences (rice vs. spaghetti) Starch-based thickeners Particles expand (sponge like) More susceptible to chemical interactions Gum-based thickeners Mass of strands tangle together to fill space liquid held between strands Less susceptible to chemical interactions Viscosity measurements Quantify a fluid s thickness at a specific point (shear rate) Permit comparison of product/liquid combinations across thickening products and within product lines Allow examination of results in relation to NDD guidelines 19

20 Starch-based thickeners reflect different patterns of thickening Nectar-consistency (Manufacturer Guidelines) Centipoise Water Apple Juice Orange Juice 2% Milk Coffee Thick & Easy Thick It Thicken Up Garcia, J. M., Chambers IV, E., Matta, Z., & Clark, M. (25). Viscosity measurements of nectar and honey-thick liquids: Product, liquid, & time comparisons. Dysphagia, 2, despite generally similar product label information (modified food starch) Honey-consistency (Manufacturer Guidelines) Centipoise Water Apple Juice Orange Juice 2% Milk Coffee Thick & Easy Thick It Thicken Up Garcia et al., (25) Results also highlight importance of base liquid Orange juice contains contains acid and pulp that can breakdown starch Milk contains protein & minerals that promote greater bonding and thickening capacity, while fats interfere with bonding Water low solids content (often less viscous) Base liquid components may have a synergistic effect with thickening agents over time 2

21 Nectar-consistency consistency (highlighted range of NDD: cp) Thicken Up Thick & Easy Thick It 7 6 Centipoise T1 T2 T3 T1 T2 T3 T1 T2 T3 T1 T2 T3 T1 T2 T3 Water Apple Juice Orange Juice 2% Milk Coffee Garcia et al. (25) Honey-consistency (highlighted range of NDD: 351 to 1,75 cp) Centipoise Thicken Up Thick & Easy Thick It T1 T2 T3 T1 T2 T3 T1 T2 T3 T1 T2 T3 T1 T2 T3 Water Apple Juice Orange Juice 2% Milk Coffee Some starches continue to absorb liquid over time (like a balloon swells with air) Gum-based thickeners Nectar-consistency Simply Thick Thik & Clear 5 4 Honey-consistency Simply Thick Thik & Clear Centipoise T1 T2 T3 T1 T2 T3 T1 T2 T3 T1 T2 T3 T1 T2 T3 Centipoise T1 T2 T3 T1 T2 T3 T1 T2 T3 T1 T2 T3 T1 T2 T3 Water Apple Juice Orange Juice 2% Milk Coffee Water Apple Juice Orange Juice 2% Milk Coffee Gum-based products maintained consistent level of thickness over time 21

22 Single-point comparisons reflect Significant variability across products and within product lines despite highly controlled preparation procedures Composition of base liquid impacts viscosity Setting time is important (especially for starch products) Samples that fit NDD ranges Nectar-consistency consistency 91% Honey-consistency consistency 36% Temperature also impacts thickness Viscosity measurements typically have an inverse relationship to temperature (thickness increase with temperature decrease) Clinical application a a thickened beverage is more viscous when cold No characteristic pattern in viscosity increase or decrease across temperature Room = 25 degrees C Serving = 4 degrees C (except coffee, 7 C) Standard 1Min 3 Min Standard 1 Min 3 Min Standard 1 Min 3 Min Standard 1 Min 3 Min Standard 1 Min 3 Min Standard 1 Min 3 Min Centipoise Water Orange Juice Coffee Water Orange Juice Coffee Thick & Easy Simply Thick Garcia, J. M., Chambers IV, E., Matta, Z., & Clark, M. (28). Serving temperature viscosity comparisons of nectar and honey-thick liquids. Dysphagia, 23,

23 Nectar Honey Thick & Easy Thicken Up Simply Thick Thick & Easy Thicken Up Simply Thick Centipoise 5 4 Centipoise T1 T2 T3 T1 T2 T3 T1 T2 T3 T1 T2 T3 T1 T2 T3 T1 T2 T3 T1 T2 T3 T1 T2 T3 T1 T2 T3 T1 T2 T3 Water Apple Juice Orange Juice 2% Milk Coffee Water Apple Juice Orange Juice 2% Milk Coffee Coffee heating of starch dispersions causes granules to swell, further increasing in viscosity What about commercially Prethickened beverages? Adeleye,, B., & Rachal,, C. (27). Comparison of the rheological properties of ready-to to-serve and powdered instant food-thickened beverages at different temperatures for dysphagic patients. Journal of the American Dietetic Association, 17, Adeleye & Rachal (27)... 2 thickeners (Resource products) Granular starch-based thickener Commercially prethickened samples Nectar and honey-like juices (AJ, OJ, Cranberry), 2% milk, & water Viscosity measured 1 o & 2 o Celsius Setting time (maximum of 3 min) 23

24 Results showed that... Commercially packaged prethickened samples measured consistently higher (more viscous) than granular starch-based product from same manufacturer regardless of base liquid or temperature or level of thickness Nectar-consistency consistency Prepared Prethickened Centipoise Water Apple Juice Orange Juice 2% Milk Cranberry Measured at 2 degrees C (about room temperature) Honey-consistency Prepared Prethickened Centipoise Water Apple Juice Orange Juice 2% Milk Cranberry Measured at 2 degrees C (about serving temperature) 24

25 Adeleye & Rachal (27) Suggest that prethickened beverages Continue to hydrate (thicken) once packaged Contain undisclosed ingredients that contribute to this process Findings highlight Variability within a product line, even for commercially packaged prethickened beverages Challenges of product consistency (produced by same manufacturer) In summary what can you expect? Challenges with quality control despite controlled preparation procedures Variability between thickening products Variability within a product line Variables interact with one another (e.g., type of product with base liquid and & setting time) Lack of product label information is a concern in analyzing effects Statistical differences may or may not be clinically significant for safe swallowing Application to Clinical Practice (Mills) What can the clinician do to promote good practice? 25

26 A Boots on the Ground View of Thickened Liquids Thin Dietary Liquid Viscosities Viscosity Labels VFSS Test Material Viscosities Thickened Liquid Viscosities A Model of Viscosity Control in Dysphagia Management Preparation and Delivery Granular Starch Based Thickeners Pre-thickened Liquids T H I C K E N E D L I Q C RH Mills 28 Mixing of a Thin Liquid VFSS Test Material by Visual SR 11 s -1 Centipoise Dysphagia Mgt Team Thin Samples Target (1.2 cp) Mills, RH (2). Dysphagia in Adults: Expanding the Diagnostic Options, Pro-ed 26

27 Mixing of a Thin Liquid VFSS Test Material by Visual SR 11 s -1 Apparent Viscosity (cp) Thick Samples Target (35 cp) Dysphagia Mgt Teams Mills, RH (2). Dysphagia in Adults: Expanding the Diagnostic Options, Pro-ed Varibar Product Line *Varibar Thin Target <15 cp **Varibar Nectar Target 3 cp Range cp ***Varibar Thin Honey Target 15 cp Range 8 18 cp ***Varibar Honey Target 3 cp Range cp 3 sec 25C Conclusions RHM * Excellent Viscosity Match ** Likely a Fair-Good Viscosity Match if Target is Achieved *** Uncertain of Adequacy of Match if Target is Achieved **** Poor Viscosity Match if Target is Achieved x DILUTION CURVE - HD-85@ SR s PREPARATION OF A 2 cp TEST SAMPLE 4 Centipoise Percent BaS 4 Mills, RH (1999). Rheology overview: Control of liquid viscosities in dysphagia management, Nutrition in Clinical Practice, Supplement, No. 5, pp. S52-S56. 27

28 Comparison in Compliance Dry Thickeners vs Prethickened Percent Compliance Q1 Q2 Q3 Q4 Q5 Q6 Q7 // Q1 Q2 Q3 Q4 Dry Thickener Quarters of Fiscal Year Prethickened Mills, RH (1999). Rheology overview: Control of liquid viscosities in dysphagia management, Nutrition in Clinical Practice, Supplement, No. 5, pp. S52-S56. Prethickened Milk and Water Products (Modified Corn Starch/Potato Starch with/without Maltodextrin) Though they are starch based they avoid three major problems common to granular starch based products: 1) No mixing needed (Staff too busy) 2) Imprecise measurement 3) Improper mixing technique Viscosities of Prethickened Liquids Apparent Viscosity (cp) Hml-Milk Hml-Apple Res-Milk Res-Apple Nectar Honey Kammer, Baillies, Gill, Hind, Hewitt, Dunn & Robbins, (2). Comparison of Commercial Thickeners for Achieving Diagnostic & Treatment Congruence (25). ASHA Convention, San Diego. 28

29 Honey-consistency (highlighted range of NDD: 351 to 1,75 cp) Centipoise Thicken Up Thick & Easy Thick It T1 T2 T3 T1 T2 T3 T1 T2 T3 T1 T2 T3 T1 T2 T3 Water Apple Juice Orange Juice 2% Milk Coffee Garcia, J. M., Chambers IV, E., Matta,, Z., & Clark, M. (25). Viscosity measurements of nectar and honey-thick liquids: Product, liquid, & time comparisons. Dysphagia, 2, Prethickend Liquid Stability Tests Viscosity Comparison Three Nectar Liquids s Res Dairy Nec Hml OR Nec Hml AP Nec min 1 min 3 min 24 hrs 48 hrs Post Mixing Measurement Time Prethickend Liquid Stability Tests Cross Brand Honey Viscosity Groups s Res Dairy Hny Hml OR Hny Hml AP Hny min 1 min 3 min 24 hrs 48 hrs Post Mixing Measurement Time 29

30 Prethickend Liquid Stability Tests Resource Dairy Nectar & Honey s Res Dairy Nec Res Dairy Hny min 1 min 3 min 24 hrs 48 hrs Post Mixing Measurement Time Prethickend Liquid Stability Tests Hormel Apple Nectar & Honey s Hml AP Nec Hml AP Hny min 1 min 3 min 24 hrs 48 hrs Post Mixing Measurement Time Prethickend Liquid Stability Tests Hormel Orange Nectar & Honey s Hml OR Nec Hml OR Hny min 1 min 3 min 24 hrs 48 hrs Post Mixing Measurement Time 3

31 Prethickend Liquid Stability Tests Cross Brand Cross Viscosity Groups s Res Dairy Nec Hml OR Nec Hml OR Hny min 1 min 3 min 24 hrs 48 hrs Post Mixing Measurement Time Prethickend Liquid Stability Tests Cross Brand Cross Viscosity Groups s Res Dairy Nec Res Dairy Hny Hml OR Nec Hml OR Hny Hml AP Nec Hml AP Hny min 1 min 3 min 24 hrs 48 hrs Post Mixing Measurement Time Simply Thick Stability Test Juice Samples 25 5-s Apple J Cranberry J Grape J KoolAid Pineapple J Prune J 5 1 min 24 hrs 48 hrs Post Mixing Measurement Time 31

32 8 Simply Thick Stability Test Supplement Samples 5 -S Choc Milk Ensure+ Van Glucerna Van Health Shake M. Shake St M Shake Van 2 Cal HN 1 min 24 hrs 48 hrs Post Mixing Measurement Time Per/Serving Cost of Thicken-up Based Thickened Liquids (Med-Diet Pricing Schedule) Product Thicken-up Viscosity Nectar Flavor Apple Servings/case 612 Cost/Serving $.97* Thicken-up Nectar Orange 734 $.81* Thicken-up Nectar Milk 612 $.97* Thicken-up Honey Apple 459 $.129* Thicken-up Honey Orange 525 $.113* Thicken-up Honey Milk 48 $.146* Serving Size: *= 4 oz Per/Serving Cost of Thick & Easy Prethickened Liquids (Med-Diet Pricing Schedule) Product Thick & Easy Viscosity Nectar Flavor Apple Servings/case Cost/Serving $.59-$.35* $.35* Thick & Easy Nectar Orange $.59-$.35* $.35* Thick & Easy Nectar Milk 27 $.98.2** Thick & Easy Honey Apple $.59-$.35* $.35* Thick & Easy Honey Orange $.59-$.35* $.35* Thick & Easy Honey Milk 27 $.98.2** Serving Size: *= 4 oz; ** = 8 oz serving 32

33 Other Cost Factors To Be Considered Labor to produce the product Waste when the product is not consumed Medical complications due to failure to consume the product Medical complications due to inappropriate viscosities consumed Medical complications due to blood sugar alterations in the diabetic patient Department of Veterans Affairs Nutrition & Food Service SLP Task Force Recommendations 1.Expand the use of Pre-thickened Liquids 2.Begin to move to the use of Gum-Based Thickeners 3.Only if the above are not possible, continue the use of Granular Starch- Based Thickeners Time for Questions and Comments 33

34 References/Suggested Readings Adeleye, B., & Rachal, C. (27). Comparison of the rheological properties of ready-to-serve and powdered instant food-thickened beverages at different temperatures for dysphagic patients. Journal of the American Dietetic Association, 17, Budke, J., Garcia, J. M., & Chambers IV, E. (28). Comparisons of thickened beverages using line spread measurements. Journal of the American Dietetic Association, 18, Garcia, J. M., Chambers IV, E., Matta, Z., & Clark, M. (25). Viscosity measurements of nectar and honey-thick liquids: Product, liquid, & time comparisons. Dysphagia, 2, Garcia, J. M., Chambers IV, E., & Molander, M. (25). Thickened liquids: Practice patterns of speech-language pathologists. American Journal of Speech-Language Pathology, 14, Garcia, J. M., Chambers IV, E., Matta, Z., & Clark, M. (28). Serving temperature viscosity comparisons of nectar and honey-thick liquids. Dysphagia, 23, Steele, C. M. (25). Searching for meaningful differences in viscosity. Dysphagia, 2, Steele, C.M. & Cichero, J.A.Y. (28). A question of rheological control. Dysphagia, 23(2),