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Nutr Hosp. 2009 Jul-Aug;24(4):492-7.

Viscosity and flow-rate of three high-energy, high-fibre enteral nutrition formulas.

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Human Nutrition Unit, Hospital Universitari Sant Joan de Reus, Rovira i Virgili University, Reus 43201, Spain.



There have been few studies evaluating how the viscosity of the enteral nutrition formulas determine the time of nutritional administration by gravity and whether viscosity causes tubes to become obstructed.


To assess how long it takes for three polymeric, hypercaloric and fibre-rich enteral nutrition formulas marketed in Europe to pass through different nasointestinal tubes by gravity and whether these formulas obstruct the tubes.


We evaluated the in vitro viscosity of the three formulas using a rotational viscometer and by calculating how long these formulas took to pass by free fall through the equipment and different calibre tubes. We also assessed the possible obstruction of the tubes or the equipment after the three formulas had been administered, simulating the administration conditions in clinical practice (1,500 ml over 24 h).


The administration time by gravity of 500 ml of each of the formulas studied was closely related to the viscosity determined in vitro of each of the formulas used. The larger the internal diameter of the tube, the shorter the emptying time by gravity or free fall. The possibility of tube obstruction was higher in the case of the two more viscous formulas.


The viscosity of the enteral nutrition formulas should be included in the labelling of the product. This information would assist the clinician to make decisions about the kind of formula to be used with different types and calibres of tube.

[Indexed for MEDLINE]

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