Purpose: Modifying milk flow rate is a common pediatric dysphagia treatment. Though past investigations have demonstrated how this can be achieved using bottle nipples, little is known about the impact of other bottle modifications. The objective of this investigation is to demonstrate how bottle vent, bottle position, and volume of milk alter bottle pressures and milk flow.
Method: A Dr. Brown's bottle filled with formula was secured to a retort stand and inverted to allow milk to free flow from a Level 1 nipple. Milk flow rate and bottle pressures were calculated under three conditions: (a) with and without a vent in place; (b) with varying volumes of milk (1-4 oz); and (c) in horizontal, semi-inverted, and completely inverted positions. Differences between flow rates under the conditions were tested using repeated-measures analysis of variance.
Results: Upon inversion, milk dripped from both vented and unvented bottles. Dripping continued throughout the 20-min testing period in the vented bottle; however, as air pressure and hydrostatic pressure declined (p < .01) in the unvented bottle, milk flow slowed and eventually ceased (p < .001). As angle of bottle inversion increased, hydrostatic pressure and milk flow rate had corresponding increases as well (p < .001). Hydrostatic pressure increased an average of 1.4 ± 0.12 mm Hg per additional ounce of formula that was added to the bottle, with corresponding increases in milk flow rate observed (p < .001).
Conclusions: Milk flow rate can be altered by feeding conditions outside of bottle nipples alone. Future work examining the clinical significance of these modifications is warranted to determine optimal interventions.