Influence of enteral nutrition viscosity on IDDSI classification, feeding tube and pump infusion compatibility

Background : Viscosity in enteral nutrition directly influences the flow characteristics of formulas through feeding tubes, the risk of tube occlusion, gastric emptying rates, nutrient absorption, and the likelihood of complications such as aspiration and reflux. Objective : This study aimed to evaluate the impact of increasing caloric density on viscosity, IDDSI (International Dysphagia Diet Standardization Initiative) classification, feeding tube and pump infusion compatibility of a powdered enteral formula prepared under standardized conditions. Methods : A fiber-free powdered enteral formula was prepared at 16 caloric densities (ranging from 1.0 to 2.5 kcal/mL) and homogenized via an ultrasonic homogenizer. Viscosity was measured by a rotational viscometer. The IDDSI classification was determined via the syringe flow test. Feeding tube compatibility was assessed by feeding tubes of varying diameters (4 to 16 Fr) under both gravity flow and infusion pump administration. Results : Viscosity increased significantly with rising caloric density (p < 0.0001; ρ = 1.0). IDDSI classification ranged from 0 to 3. Under gravity flow, formulas with caloric densities between 1.9 and 2.4 kcal/mL exhibited mild flow resistance through 12 Fr feeding tubes. Infusion pump failures were observed at densities ≥2.0 kcal/mL, with frequent flow errors and occlusion alarms occurring. Conclusion : Higher caloric density is associated with increased viscosity, which affects IDDSI classification and infusion performance. Enteral formulas ≥1.9kcal/mL or IDDSI 2 require tailored feeding tubes and pump infusion to avoid clinical failures.