The effect of fluid density and volume on the accuracy of test weighing in a simulated oral feeding situation.

BACKGROUND

For preterm infants and infants who have difficulty with oral feeding, excessive drooling during oral feedings can result in inaccurate assessment of intake. The drooled volume is typically estimated by visual and tactile assessment of the bib. Research, however, has demonstrated that visual assessment is inaccurate.

PURPOSE

The purpose of this study was to determine the accuracy of a scale that was used for the test weighing of milk that was drooled during a study of oral feeding for preterm infants. Additionally, the effect of weighing solutions with different densities on the accuracy of test weights was examined.

METHOD

Descriptive, comparative design.

PROCEDURES

A simulated feeding situation was performed using 3 fluids (water, Enfamil(20), and Enfamil(24)) and 3 volume ranges (1 mL to 10 mL, 11 mL to 20 mL, and 21 mL to 30 mL). Data collection sessions were conducted for each of the 3 fluids using each range of volumes, for a total of 180 test weights. The research assistant performing the test weights was blinded to the preweight of the bib and the amount of fluid being applied to the bib.

RESULTS

Differences between the actual volume applied to the bib and the volume estimated by the scale were very small, with 51% of the differences equaling 0 mL and 48% of the differences between -1 mL and 1 mL. There were significant differences in errors related to both the type of fluid (F = 25.7; df = 2; P < 0.001) and volume range (F = 12.7; df = 2; P < 0.001), as well as for the interaction between the 2 factors (F = 7.02; df = 4; P < 0.001). Water had significantly less mean error than either formula, and large volumes had significantly greater mean error than either small or medium volumes.

CONCLUSIONS

Test weighing is an accurate method for measuring fluids of different densities and volumes in a simulation of drooling during oral feeding. The increased error with larger volumes of higher density solutions was not clinically significant. The study supports the need to consider both the accuracy of the scale and characteristics of the fluid when test weighing is used to measure volumes of fluids.