Does What I Say Matter? Influence of Verbal Instruction on Bolus Size: Pilot Data

Research Objectives: To evaluate the effects, if any, verbal instructions and delivery method may have on bolus size with self-administration of thin liquids.

Design: Prospective, randomized, repeated measure study.

Setting: Freestanding rehabilitation hospital.

Participants: Convenience sample of healthy adults with no history of dysphagia.

Interventions: Subjects were randomized into either the cup or straw group. Each subject consumed eight boluses of water under four different instructions: 1) Take a drink; 2) Take a comfortable sip; 3) Take a small sip: 4) Take a small sip like it is hot coffee. Order of instructions was randomized. Each subject had eight cups prepared (4 cups 60-ml water in 120-ml cup; 4 cups120-ml water in 240-ml cup). Subjects received new cup for each drink instruction. Ratio of liquid to cup size was the same between two cup sizes.

Main Outcome Measures: Bolus size extrapolated from weight of cup / water before and after each administration.

Results: Ten healthy subjects (5 men; 5 women), age range 22-58 years, mean age 39.3 years (SD=11.4 years) participated in the study. Overall, the differences between the mean volume consumed using various instructions were statistically significant (take a drink=28.80 ml; comfortable sip=14.35 ml; small sip=5.3 ml; small sip like it is hot coffee=3.01 ml; F=22.51, p≥.0001). Differences in mean volume consumed by cup size (i.e., 4-ounce cup vs. 8-ounce cup) were not statistically significant (p=.581). Differences in mean volume consumed by straw or cup presentation were not statistically significant (p=.914).

Conclusions: Results suggest verbal instruction has an influence upon bolus size with healthy adults with the semantic cue instruction (hot coffee) resulting in the lowest volume consumed. No differences were observed in amount consumed by cup size or straw vs. cup presentation. Reducing bolus size is a common clinical strategy to eliminate or reduce aspiration. It is important for the dysphagia rehabilitation team to understand the influence verbal instructions may have upon bolus size to facilitate a safe swallow.

Author(s) Disclosures: The authors have no conflicts of interests to disclose.