Determining Viscosity of Blenderized Formula: A Novel Approach Using the International Dysphagia Diet Standardisation Initiative Framework

Background Blenderized formula (BF) can be used in place of standard enteral formula and is composed of blenderized whole foods and purees. Benefits of using BF include reduced vomiting and retching, in part related to a higher viscosity. Commercially prepared BFs vary significantly in viscosity when comparing available products. Viscosity can be measured using a viscometer, although this requires expensive and sophisticated equipment. We proposed an alternative method to describe viscosity of BFs using the International Dysphagia Diet Standardisation Initiative (IDDSI) framework. This flow test provides a simple and objective method to describe liquid thickness and requires only a 10-mL luer tip syringe and stopwatch. Methods Full-strength BFs were measured using the IDDSI flow test and compared with a standard enteral formula. BFs were then diluted until a slightly thick viscosity was achieved, which correlated to the viscosity of the reference formula. Results IDDSI flow-test results indicated that undiluted BFs ranged in viscosity, from slightly thick to extremely thick, when measured at room temperature. The volume of water required to achieve a slightly thick viscosity ranged from 0 to 270 mL per serving, resulting in a wide variation in dilution of formula. Conclusion The IDDSI flow test was simple to perform and can serve as a tool to determine the viscosity of BFs.