AbstractPurpose: Adequate enteral nutrition (EN) delivery to critically ill patients is difficult to achieve. Given the large number of unpreventable influences affecting adequate caloric intake, further research on preventable influences of adequate EN administration is warranted. The purpose of this study was to evaluate whether hang height of EN formula, formula viscosity, or flow rate influences pump accuracy and formula delivery. Methods: Formulas of varying viscosities (1.0, 1.5, and 2.0 kcal/mL) were infused at different hang heights (0, 6, 12, and 18 inches) and rates (20, 40, and 80 mL/h). The mean percent difference and the bias between the programmed volume, volume reported, and volume delivered were calculated for the different hang heights, formula compositions, and infusion rates studied. Results: For all prespecified hang heights and infusion rates, the volume delivered was less than the programmed volume and volume reported; the mean percent difference increased as the hang height decreased. The volume was overestimated for both the programmed volume (14.4% ± 5.5%) and volume reported (12.9% ± 6.7%) compared with volume delivered. The overestimation bias was significantly influenced by differences in hang height as well as type of formula (P < .0001, each) but not by rate of delivery (P = .4633 for programmed volume and .8411 for volume reported). Conclusions: Measures should be taken in clinical practice to ensure adequate hang height of EN. Appropriate hang height of EN may result in more accurate delivery of nutrition provisions to the critically ill patient and subsequently reduce complications related to underfeeding.