Reflections on Clinical and Statistical Use of the Penetration-Aspiration Scale.

The 8-point Penetration-Aspiration Scale (PAS) was introduced to the field of dysphagia in 1996 and has become the standard method used by both clinicians and researchers to describe and measure the severity of airway invasion during swallowing. In this article, we review the properties of the scale and explore what has been learned over 20 years of use regarding the construct validity, ordinality, intervality, score distribution, and sensitivity of the PAS to change. We propose that a categorical revision of the PAS into four levels of increasing physiological severity would be appropriate. The article concludes with a discussion of common errors made in the statistical analysis of the PAS, proposing that frequency distributions and ordinal logistic regression approaches are most appropriate given the properties of the scale. A hypothetical dataset is included to illustrate both the problems and strengths of different statistical approaches.

Use of topical nasal anesthesia during flexible endoscopic evaluation of swallowing in dysphagic patients.

OBJECTIVE: This study aimed to determine the effect of topical lidocaine on Penetration-Aspiration Scale (PAS) scores and patient comfort and tolerance of flexible endoscopic evaluation of swallowing (FEES) examinations in dysphagic patients. METHODS: Adults with dysphagia referred for swallowing evaluation were recruited to participate in consecutive nonanesthetized and then anesthetized FEES examinations. Under endoscopic visualization, participants consumed 6 swallows consisting of graduated volumes of milk, pudding, and cracker in each condition and recorded their discomfort and tolerance in the 2 conditions. Penetration-Aspiration Scale scores were assigned in blinded fashion for each swallow. RESULTS: Twenty-five adults participated in the study. Although there was no statistically significant effect of anesthesia on PAS scores (P=.065), the odds of a higher PAS score were 33% higher during anesthetized swallows. The anesthetized condition yielded significantly less discomfort and pain during the examination, significantly less pain and discomfort during insertion and removal of the endoscope, and significantly greater overall tolerance than the nonanesthetized condition. CONCLUSION: The use of topical lidocaine during FEES may impair swallowing ability in patients with dysphagia, but this result does not achieve statistical significance. Topical nasal anesthesia significantly reduces subjective pain and discomfort and improves tolerance during FEES.

Stability of aspiration status in healthy adults.

OBJECTIVES: In multiple separate studies, we consistently found that approximately 30% of asymptomatic healthy older adults silently aspirated liquids during flexible endoscopic evaluation of swallowing (FEES). We subsequently questioned whether aspiration status remained stable in healthy older adults over time. The purpose of this study was to determine the stability of aspiration status in healthy older adults over time. METHODS: Eighteen healthy older participants, comprising of 9 aspirators and 9 nonaspirators whose aspiration status was identified in a previous study, underwent a second FEES approximately 6 to 21 months later. The participants contributed 36 swallows, comprising 5-, 10-, 15-, and 20-mL boluses of milk (ie, 1 bolus of each volume of skim, 2%, whole, and soy milk) and water via cup and straw delivery, during the original FEES. An abbreviated protocol was administered for the repeat FEES. The Penetration-Aspiration Scale was used to rate all swallows. RESULTS: A McNemar test demonstrated no change in aspiration status among participants between the initial test and the retest (p > 0.999). CONCLUSIONS: In this cohort, the aspiration status was stable over about 12 months. This finding lends credence to the premise that trace aspiration of liquids may be a normal and consistent finding in some healthy older adults.

The effects of topical anesthetic on swallowing during nasoendoscopy.

OBJECTIVES/HYPOTHESIS: To assess the effects of a typical otolaryngologic dose of 1 mL of 4% lidocaine on penetration aspiration scale scores and participant discomfort during flexible endoscopic evaluation of swallowing. STUDY DESIGN: A prospective pilot study. METHODS: Twenty healthy participants consumed 12 swallows consisting of graduated volumes of milk, water, pudding, and cracker in anesthetized and nonanesthetized conditions. Each participant was randomly selected to begin with the anesthetized or nonanesthetized condition. Each participant returned within 7 days to repeat the study in the other condition. Digital recordings of their evaluations were scored via the penetration-aspiration scale in a blinded fashion. Participants recorded their discomfort and tolerance of each flexible endoscopic evaluation of swallowing. RESULTS: The anesthetized condition yielded significantly worse swallowing function (P = .001) than the nonanesthetized condition. The nonanesthetized condition yielded greater discomfort and pain during the procedure (P = .006, .018), greater pain during insertion and removal of the endoscope (P = .002, .003) and less overall tolerance (P = .016) than the anesthetized condition. CONCLUSIONS: A typical otolaryngologic anesthetic dose of 1 mL of 4% lidocaine during flexible endoscopic evaluation of swallowing predisposed healthy young adults to higher penetration aspiration scale scores (less safe swallowing) than the nonanesthetized condition; however, the anesthetic reduced discomfort and provided better overall tolerance. Future studies need to evaluate the effects of lower doses of lidocaine (0.2 and 0.5 mL) on swallowing function and comfort.

Effects of chemesthetic stimuli mixtures with barium on swallowing apnea duration.

OBJECTIVES/HYPOTHESIS: This study tested the hypotheses that swallowing apnea duration (SAD) will increase given barium versus water, chemesthetic stimuli (i.e., water < ethanol, acid, and carbonation) mixed with barium, age (older > younger), and genetic taste differences (supertasters > nontasters). STUDY DESIGN: Prospective group design. SETTING: University Medical Center. METHODS: Eighty healthy women were identified as nontasters and supertasters, equally comprising two age groups: 18 to 35 years and 60+ years. The KayPentax Swallowing Signals Lab was used to acquire SAD via nasal cannula during individually randomized swallows of 5 mL barium, 2.7% w/v citric acid with barium, carbonation with barium, and 50:50 diluted ethanol with barium. Data were analyzed using path analysis, with the mediator of chemesthetic perception, adjusted for repeated measures. RESULTS: Significant main effects of age (P = .012) and chemesthetic stimuli (P = .014) were found, as well as a significant interaction between chemesthetic stimuli and age (P = .028). Older women had a significantly longer SAD than younger women. Post hoc analyses revealed that barium mixed with ethanol elicited a significantly longer SAD than other bolus conditions, regardless of age group. There were no significant differences in SAD between barium and water conditions, and no significant effect of chemesthetic perception (P > .05). CONCLUSIONS: Ethanol added to barium elicited longer SAD compared to plain barium, but not the other chemesthetic conditions. Older women had a longer SAD than younger women in all conditions. These findings may influence design of future studies examining effects of various stimuli on SAD.

Main taste effects on swallowing apnea duration in healthy adults.

OBJECTIVE: This study examined swallowing apnea duration (SAD) and respiratory phase patterns as a function of taste, tastes combined with barium, age, and genetic taste group. STUDY DESIGN: Prospective group design. SETTING: University medical center. SUBJECTS AND METHODS: Eighty healthy adult women were identified as nontasters and supertasters and equally comprised 2 age groups: 18 to 35 years (n = 40) and 60+ years (n = 40). The KayPentax Swallowing Signals Lab was used to acquire SAD and respiratory phase patterns via nasal cannula during randomized 5-mL swallows of water, 1.0 M sucrose (sweet), 1.0 M sodium chloride (salty), and 0.032 M caffeine (bitter) alone and mixed with barium. The SAD and respiratory patterns were analyzed in a linear mixed model and a binary logistic regression generalized estimating equation model, respectively. RESULTS: A significant main effect of age was found (P = .007). Older women demonstrated longer SAD than younger women. There were no significant effects of taste or genetic taste group on SAD. There was a significant interaction between barium and supertaster status; SAD was shorter in supertasters when barium was included. There were no significant differences in respiratory patterns between age groups, genetic taste groups, or among taste stimuli. CONCLUSION: Advanced age elicited longer SAD, a robust finding in repeated investigations from multiple laboratories. Main tastes did not affect SAD or respiratory phase patterns. Genetic taste group altered SAD when barium was combined with the taste. That is, taste + barium shortened SAD in supertasters. This finding may affect clinical management of dysphagia patients and warrants further investigation.

Effects of chemesthetic stimuli, age, and genetic taste groups on swallowing apnea duration.

OBJECTIVE: This study tested the hypotheses that swallowing apnea duration (SAD) will increase given chemesthetic stimuli (ie, water < ethanol, acid, and carbonation), age (older > young), and genetic taste differences (supertasters > nontasters). STUDY DESIGN: Prospective group design. SETTING: University medical center. SUBJECTS AND METHODS: Eighty healthy adult women were identified as nontasters and supertasters, equally comprising 2 age groups: 18 to 35 years (n = 40) and 60+ years (n = 40). The KayPentax Swallowing Signals Lab was used to acquire SAD via nasal cannula during individually randomized swallows of 5 mL deionized water, 2.7% w/v citric acid, seltzer water, and 50:50 diluted ethanol/water. Data were analyzed using path analysis, with the mediator of chemesthetic perception, adjusted for repeated measures. RESULTS: Significant main effects of chemesthetic stimuli (P = .002), age (P < .001), and genetic taste differences (P = .04) on SAD were found. Older women and supertasters had longer SADs than young women and nontasters. Post hoc analyses revealed ethanol and acid boluses elicited significantly longer SADs than water boluses did. There was no significant effect of chemesthetic perception (P > .05). CONCLUSION: SAD in healthy women increased with changes in chemesthetic stimuli, older age, and in supertasters versus nontasters. It is unclear at this stage if increased SAD is a helpful mechanistic change (potentially protective against aspiration) or a maladaptive change (associated with aspiration). Future research should use these chemesthetic changes in bolus properties to assess if increased SAD decreases aspiration in patients with dysphagia while accounting for genetic taste differences.

Pressure profile similarities between tongue resistance training tasks and liquid swallows.

Tongue-pressure resistance training is known to increase tongue strength in seniors and individuals with stroke-related dysphagia. However, evidence of associated functional improvements in swallowing is equivocal. We investigated similarities in pressure waveform profiles between swallowing and several tongue-palate pressure tasks to identify tasks that may be best suited for inclusion in tongue-pressure resistance training protocols for patients who are unable to safely perform real bolus swallows in treatment. Tongue-palate pressures were recorded in 20 healthy young adults. Participants performed water and nectar-thick juice swallows, effortful and noneffortful saliva swallows, and "half-maximum" tongue-palate partial-pressure tasks emphasizing either anterior or posterior tongue-palate contact at different speeds. Pressure slopes (amplitude change over time) during the pressure application (rise) and withdrawal (release) phases were analyzed. A subset of four tasks with the greatest similarity in slope characteristics to those seen in bolus swallows was identified: anterior-emphasis half-maximum tongue-palate presses, posterior-emphasis maximum isometric tongue-palate presses, posterior-emphasis half-maximum slow tongue-palate presses, and effortful saliva swallows. We propose that future research should explore the degree to which swallowing improvements are obtained from treatment protocols that emphasize these tasks.