Effect of a gum-based thickener on the safety of swallowing in patients with poststroke oropharyngeal dysphagia

Abstract

Background: Increasing viscosity with thickening agents is a valid therapeutic strategy for oropharyngeal dysphagia (OD). To assess the therapeutic effect of a xanthan gum-based thickener (Nutilis Clear^® ) at six viscosities compared with thin liquid in poststroke OD (PSOD) patients.

Methods: A total of 120 patients with PSOD were studied in this controlled, multiple-dose, fixed-order, and single-blind study using videofluoroscopy (VFSS). A series of boluses of 10 mL thin liquid and 2000, 1400, 800, 450, 250, and 150 mPa s viscosities were given in duplicate, interrupted in case of aspiration. We assessed the safety and efficacy of swallow and the kinematics of the swallow response.

Key results: A total of 41.2% patients had safe swallow at thin liquid which significantly increased for all viscosities from 71.9% at 150 mPa s to 95.6% at 1400 mPa s (P < .001). PAS score (3.7 ± 2.3) at thin liquid was also reduced by increasing bolus viscosity (P < .001). The prevalence of patients with aspiration at thin liquid was 17.5% and decreased at all viscosities (P < .01), except at 150 mPa s. Increasing viscosity shortened time to laryngeal vestibule closure (LVC) at all viscosities (P < .01) and reduced bolus velocity at ≥450 mPa s (P < .05). The prevalence of patients with pharyngeal residue at each viscosity 37.7%-44.7% was similar to that at thin liquid (41.2%).

Conclusions and inferences: The prevalence of unsafe swallow with thin liquids is very high in PSOD. Increasing shear bolus viscosity with this xanthan gum-based thickener significantly increased the safety of swallow in patients with PSOD in a viscosity-dependent manner without increasing the prevalence of pharyngeal residue.

Keywords: aspiration; deglutition disorders; shear viscosity; stroke; swallow response; thickener; xanthan gum.

Figure 1

Study design

Figure 2

Percentage of PSOD patients with safe/unsafe swallow at each level of viscosity. “N” represents the number of patients who performed the bolus out of the PP population (114). The percentage of patients with unsafe swallow includes those with aspirations at the former viscosity who discontinued due to the safety rule. Percentage of patients who discontinued at each viscosity: thin liquid (0.0%), 150 mPa s (12.3%), 250 mPa s (8.8%), 450 mPa s (4.4%), 800 mPa s (1.8%), 1400 (1.8%), 2000 mPa s (0.9%). *P < .05; **P < .01; ***P < .001 vs thin liquid

Figure 3

Percentage of PSOD patients with safe/unsafe swallow compared between levels of viscosity. Data of patients who discontinued due to the safety rule were imputed with the last observation carried forward. Values are presented for the PP population (114).*P < .05; **P < .01; ***P < .001

Figure 4

Percentage of patients with PSOD of the PP population (114) with oral and pharyngeal residue at each viscosity level. “N” represents the population who performed the bolus. *P < .05; **P < .01; ***P < .001 vs thin liquid

Figure 5

Dose‐response curves for the therapeutic effect of the gum‐based thickener on safety and efficacy of swallowing in patients with PSOD. The upper panel shows the curve of the viscosity‐dependent response represented by the percentage of patients with safe swallows vs the log of the viscosity. The lower panel shows the curve representing the effects on the prevalence of oral and pharyngeal residue vs the log of the viscosity. The shadowed area represents the therapeutic range (150‐800 mPa s) of the product

Figure 6

Time to LVC at each viscosity level. The upper panel shows mean time to LVC at each viscosity. The lower panel shows time to LVC plotted against safe/unsafe swallow at each viscosity level. Time to LVC was delayed in patients with unsafe swallowing at all viscosity levels except for 2000 mPa s. Time to LVC <160 ms (green line): safe swallowing as established in a study with healthy volunteers.4Time to LVC ≥340 ms (red line): cutoff time to detect the presence of unsafe swallowing in poststroke patients according to previous studies.12 *P < .05; **P < .01; ***P < .001

Figure 7

Mean bolus velocity from GPJO to UESO at each viscosity level. Bolus velocity was reduced above 450 mPa s. *P < .05; **P < .01; ***P < .001 vs thin liquid

Figure 8

Comfortability while swallowing the product. The comfortability while swallowing the product at each viscosity level was evaluated by using a 9‐point Likert scale to the following sentence: “I felt comfortable while swallowing this product.” Likert scale score is divided into three categories for each viscosity. For the statistical analysis, these three catergories and the category of missing values were used. “N” represents the population who answered the question, the category of missing values is not shown in the figure. *P < .05; **P < .01; ***P < .001 vs thin liquid