Preliminary Investigation of Swallowing Apnea Duration and Swallow/Respiratory Phase Relationships in Individuals with Cerebral Vascular Accident

Swallowing apnea duration (SAD) and swallow-respiratory phase relationships were examined in individuals with cerebral vascular accident (CVA) and dysphagia who aspirated (n = 11) and did not aspirate (n = 15). Simultaneous videofluoroscopic and respiratory measures were recorded across 5-, 10-, 15-, and 20-ml thin and thick liquid bolus trials. These data were also compared with that previously acquired with healthy older adults (n = 20). A moderate amount of systematic missing data was evidenced in the individuals who were dysphagic and especially those who aspirated subsequently limiting inferential analyses. Only 1 of the 11 participants who aspirated and 7 of the 15 who did not aspirate completed all 16 conditions. Six of the remaining ten who aspirated had missing data subsequent to termination of trials due to aspiration risk. The remaining four and seven of the eight who did not aspirate had missing data due to poor respiratory waveforms. From the remaining data, it was found that SAD and respiratory phase relationships differed among individuals with dysphagia and CVA (i.e., those who aspirate vs. those who do not aspirate) and healthy older adults. SAD was found to be longer for those who aspirated versus those who did not for all bolus viscosities and volumes with the exception of thick-liquid 10-ml boluses. In addition, SAD from those that aspirated was twice as long as that found in healthy older adults for all conditions. Regarding respiratory phase relationships, there was a difference between the proportions of respiratory patterns in those who aspirated versus those who did not. Those who aspirated demonstrated a markedly greater percentage of swallows that interrupted inhalation. In addition, the inhale-swallow-inhale pattern occurred with a greater frequency as swallowing severity increased. Healthy older adults, those who did not aspirate, and those who aspirated used the inhale-swallow-inhale pattern 0.1%, 3.0%, and 9.0%, respectively.     

Effects of Nasogastric Tubes on the Young, Normal Swallowing Mechanism

The present study aimed to investigate the effects of different-sized nasogastric tubes on swallowing speed and function in 10 young normal volunteers. Using X-ray visualization, liquid barium swallows were recorded on video (videofluoroscopy) under three experimental conditions: no nasogastric tube, fine-bore nasogastric tube, and wide-bore nasogastric tube. Nasogastric tubes slowed swallowing but did not alter swallowing function, namely bolus transit and clearance, and airway protection. The presence of a wide-bore nasogastric tube caused significant duration changes in several swallowing measures, namely duration of stage transition, duration of pharyngeal response, duration of pharyngeal transit, and duration of upper esophageal sphincter opening. Similar trends were seen for the fine-bore tube. The implications for nonoral feeding of patients with swallowing disorders are discussed.     

Temporal and Durational Patterns Associating Respiration and Swallowing

This study obtained initial normative data on the temporal coordination of respiration and swallowing events in 12 young adults using a first-generation Respirodeglutometer. In addition, direction of airflow before and after deglutive apnea was obtained. Three swallows of two viscosities of bolus material were performed by each subject, yielding a total of 72 swallows. Qualitative and quanitative analyses were performed. Time of onset of submental surface electromyography and time of laryngeal movement were found to differ between males and females. Males began submental muscle contraction before females and laryngeal movement after females. Duration of deglutition apnea for all swallows was 0.75 ± 0.14 sec. Expiration occurred before the deglutition apnea 93% of the time and after the deglutition apnea 100% of the time. A modal pattern of events obtained with the Respirodeglutometer was present in 42% of the swallows, and an additional 47% had only one event differ from that order.     

Structural Displacements in Normal Swallowing: A Videofluoroscopic Study

Dynamic videofluoroscopic swallow studies were performed on 60 normal adult volunteers to establish normative data for displacement of upper aerodigestive tract structures during deglutition. Variables evaluated included hyoid bone displacement, larynx-to-hyoid bone approximation, pharyngeal constriction, and the extent of pharyngoesophageal sphincter (PES) opening during liquid swallows of 1, 3, and 20 cc. Results showed direct relationships between bolus size and hyoid displacement, between bolus size and PES opening, and between bolus size and pharyngeal constriction. Only hyoid-to-larynx approximation remained unchanged across bolus sizes. Sex differences were noted for all variables except PES opening. Reliability for most measurement variables was excellent. To our knowledge, normative data for pharyngeal constriction and larynx-to-hyoid approximation have not previously been described.     

Effects of Bolus Volume on Pharyngeal Contact Pressure During Normal Swallowing

This cross-sectional study investigated the effect of bolus volume on contact pressure within the pharynx and upper esophageal sphincter (UES). Three solid-state manometric pressure sensors were placed transnasally into the pharynx and the proximal esophagus of 40 participants (gender equally represented and between the ages of 20 and 45 years). Participants completed five repetitions each of three swallowing conditions: 5-, 10-, and 20-ml water bolus swallows. Repeated-measures ANOVA revealed no significant differences in the amplitude of pharyngeal contact pressure between the three swallowing conditions (sensor 1: p = 0.627, sensor 2: p = 0.764). Similarly, for durational measures nonsignificant main effects were found at both sensor 1 (p = 0.436) and sensor 2 (p = 0.350). Significant differences were found in UES pressure between the three conditions of bolus swallows (p = 0.000), with negative pressure in the UES inversely proportionate to bolus volume. However, durational measures of UES relaxation pressure were not significantly different between all conditions (p = 0.473). This study demonstrates no significant pressure differences of amplitude and duration between swallowing conditions in the pharynx. At the level of the UES, smaller boluses generated greater negative pressure.     

Inter- and Intrajudge Reliability of a Clinical Examination of Swallowing in Adults

This study investigates inter- and intrajudge reliability of a clinical examination of swallowing in adults. Several investigations have sought correlations between clinical indicators of dysphagia and the actual presence of dysphagia as determined by videofluoroscopy. Whereas some investigations have reported interjudge reliability for the videofluoroscopic measures employed, none have reported reliability for clinical measures. Without established reliability for rating clinical measures, conclusions drawn regarding the utility of a measure for detecting aspiration can be called into question. Results of the present study indicate that fewer than 50% of the measures clinicians typically employ are rated with sufficient inter- and intrajudge reliability. Measures of vocal quality and oral motor function were rated more reliably than were history measures or measures taken during trial swallows. There is a need to define more clearly the measures employed in clinical examinations and to be consistent in reporting reliability for clinical measures of swallowing function in future research.     

Videomanometric Analysis of Supraglottic Swallow, Effortful Swallow, and Chin Tuck in Healthy Volunteers

Simultaneous videoradiography and solid-state manometry (videomanometry) was applied in eight healthy volunteers (four women, four men; age range 25–64 years, mean age 41 years) without swallowing problems. Three different swallowing techniques were tested; supraglottic swallow, effortful swallow, and chin tuck. Seven videoradiographic variables and six manometric variables were analyzed. The supraglottic swallowing technique did not differ significantly from that of the control swallows. The effortful swallow had a significantly (p= 0.0001) reduced hyoid–mandibular distance preswallow due to an elevation of the hyoid and the larynx, which caused a significantly (p= 0.007) reduced maximal hyoid movement and a significantly (p= 0.009) reduced laryngeal elevation during swallow. The chin tuck swallow had a significantly (p= 0.001) reduced laryngohyoid distance and also a significantly (p= 0.004) reduced hyoid–mandibular distance. The chin tuck swallow also displayed significantly (p= 0.003) weaker pharyngeal contractions. Videomanometry allows for analysis of bolus transport, movement of anatomical structures, and measurement of intraluminal pressures. These variables are important when evaluating swallowing techniques. In the present study, we made a few observations that never have been reported before. When healthy volunteers performed supraglottic swallow, they performed the technique somewhat differently. Therefore, we assume dysphagic patients would need a substantial period of training to perform a technique efficiently. Chin tuck could impair protection of the airways in dysphagic patients with weak pharyngeal constrictor muscles.     

Comparative Review of Techniques for Recording Respiratory Events at Rest and during Deglutition

The coordination between swallowing and respiration is essential for safe feeding, and noninvasive feeding-respiratory instrumentation has been used in feeding and dysphagia assessment. Sometimes there are differences of interpretation of the data produced by the various respiratory monitoring techniques, some of which may be inappropriate for observing the rapid respiratory events associated with deglutition. Following a review of each of the main techniques employed for recording resting, pre-feeding, feeding, and post-feeding respiration on different subject groups (infants, children, and adults), a critical comparison of the methods is illustrated by simultaneous recordings from various respiratory transducers. As a result, a minimal combination of instruments is recommended which can provide the necessary respiratory information for routine feeding assessments in a clinical environment.     

Effects of Physostigmine on Swallowing and Oral Motor Functions in Patients with Progressive Supranuclear Palsy: A Pilot Study

The purpose of this pilot study was to investigate whether cholinergic stimulation reduces swallowing and oral motor disturbances in patients with progressive supranuclear palsy (PSP). A controlled, double-blind crossover trial of physostigmine, a centrally active cholinesterase inhibitor, and placebo was conducted. Patients were randomized to a 10-day crossover placebo-controlled double-blind trial of physostigmine at their previously determined best dose administered orally every 2 hr, six times per day. Patients were evaluated with ultrasound imaging of the oropharynx and an oral motor examination at baseline and during the third or fourth days of each study phase (placebo and drug). Under the double-blind placebo-controlled conditions, patients showed no statistically significant improvement in oral motor functions or swallow durations. Because patients with PSP have increased sensitivity to cholinergic blockade compared with control subjects, studies with newer, more potent cholinergic stimulating agents need further exploration. Suggestions for future research include the evaluation of newer direct cholinergic agonists in the treatment of the less-impaired PSP patients who may have a greater number of cholinergic neurons preserved and the evaluation of combined therapies.     

Voluntary and Reflex Influences on the Initiation of Swallowing Reflex in Man

The electrophysiological features of voluntarily induced and reflexive/spontaneous swallows were investigated. In normal subjects, swallows were elicited by infusing water either into the mouth (1–3 ml) or directly into the oropharyngeal region through a nasopharyngeal cannula (0.3–1 ml). For water infused orally, subjects were either requested to swallow voluntarily or instructed to resist swallowing and maintain the horizontal head position until swallowing occurred reflexively. Spontaneous saliva swallowing was investigated in patients with severe dysphagia who had a prominent clinical picture of suprabulbar palsy. Comparisons between different swallowing types were made by measuring the time interval between the onset of submental electromyographic activity (SM-EMG) and the onset of the upward movement of the larynx recorded by a movement sensor. This interval was less than 100 ms, even frequently less than 50 ms, in reflexive/spontaneous swallows, while in voluntarily induced swallows it was substantially longer. The rising time of submental muscle's excitation was also shorter in reflexive/spontaneous swallows. It was suggested that the triggering of voluntarily induced swallows commences more than 100 ms before the onset of swallowing reflex and that this mechanism is under the control of corticobulbar–pyramidal pathways. If the swallowing reflex is triggered within such a short period of time following the onset of SM-EMG, the central control by the bulbar swallowing center should be effective until the end of oropharyngeal swallowing.     

Effects of Age, Gender, Disease, and Multisystem Involvement on Oxygen Saturation Levels in Dysphagic Persons

The purpose of this study was to examine the effects of age, gender, disease, and multisystem involvement on SpO₂ levels of 104 dysphagic patients and 77 nondysphagic persons. Results indicated that solid aspirators had lower SpO₂ levels than liquid aspirators, penetrators, and nondysphagics. In addition, SpO₂ levels varied by age, with older persons having lower levels than younger persons among dysphagics but not among nondysphagics. Patients with COPD had lower SpO₂ levels than dysphagics with other disorders. Significant interactions were found among age, gender, and disease. Multisystem involvement was found not to be a factor in SpO₂ levels. It was concluded that although normal aging processes reduce swallowing and pulmonary functioning, it became a significant factor only when combined with an assault to the system, such as CVA or COPD.     

Teaching Speech Pathology Students the Interpretation of Videofluoroscopic Swallowing Studies

This article examines a teaching package that was designed to cover the progression of skills agreed to by clinicians and educators as being pertinent to interpreting Videofluoroscopy Swallowing Studies (VFSSs). Sessions taught included knowledge of anatomy and physiology of swallowing, examination and identification of structures and landmarks from radiographs, and the use of an assessment scale such as the Bethlehem Assessment Scale (BAS) to interpret VFSSs. The ability to interpret eight VFSSs using the BAS was used as the final assessment. ANOVA for repeated measures and post hoc tests using Tukey's HSD statistic revealed that there was a statistically significant correlation between students' knowledge of anatomy and physiology and their knowledge of radiographic anatomy. There was a statistically significant correlation between their knowledge of radiographic anatomy and their ability to interpret videofluoroscopic examinations, as assessed using the BAS. There was also a statistically significant correlation between their knowledge of anatomy and physiology and their ability to interpret videofluoroscopic examinations using the BAS.     

Effect of Liquid Bolus Consistency and Delivery Method on Aspiration and Pharyngeal Retention in Dysphagia Patients

There is no empirically derived consensus as to what food consistency types and method of food delivery (spoon, cup, straw) should be included in the videofluoroscopic swallowing (VFSS) studies. In the present study, we examine the rates of aspiration and pharyngeal retention in 190 dysphagic patients given thin (apple juice) and thick (apricot nectar) liquids delivered by teaspoon and cup and ultrathick (pudding-like) liquid delivered by teaspoon. Each patient was tested with each of the bolus/delivery method combinations. The fractions of patients exhibiting aspiration for each bolus/method of delivery combination were (1) thick liquids (cup), 13.2%; (2) thick liquids (spoon), 8.9%; (3) thin liquids (cup), 23.7%; (4) thin liquids (spoon), 15.8%, (5) ultrathick liquids (spoon), 5.8%. In each comparison [thick liquid (cup) vs. thick liquid (spoon), thin liquid (cup) vs. thin liquid (spoon), thick liquid (cup) vs. thin liquid (cup), thick liquid (spoon) vs. thin liquid (spoon), and thick liquid (spoon) vs. ultrathick liquid (spoon)], the p value for χ² was <0.001. These results suggest that utilizing thin, thick, and ultrathick liquids and delivery by cup and spoon during a VFSS of a patient with mild or moderate dysphagia can increase the chances of identifying a consistency that the patient can swallow without aspirating and without pharyngeal retention after swallowing. Submitted December 22, 1999; accepted September 6, 2000 with revision     

Exploration of Pharyngeal Swallowing by Audiosignal Recording

The aims of this study were to analyze the following by audiorecording of swallows: (1) the influence on the volume and consistency of ingested substances on the audiosignal recorded during separate swallows; and (2) the characteristics of successive swallows during ingestion of 100 ml of the same substances to define deglutitive behaviors. Volunteers followed two protocols. Protocol (P) 1 comprised ingestion of 100 ml of water or yoghurt in successive swallows and Protocol 2 comprised separate swallows of different volumes of the same substances. Audiosignal recordings were made with a dynamic microphone. The following parameters were measured in P1: total time of ingestion (TT), number of swallows necessary for ingestion (N), and spontaneous swallowing intervals (SI). In P2 the duration (d) of each signal was measured according to consistency and volume. Mean (m) values were then calculated (TTm, Nm, SIm, and dm). During P1, TTm for yoghurt was significantly longer than for water (23.1 vs. 6.5 sec (men) and 21.8 vs. 7.8 sec (women). Nm was also greater for yoghurt (10.1 vs. 4.3 (men) and 10.0 vs. 4.8 (women). Three types of swallowing behavior were defined according to SI: swallowing at regular intervals (Reg) with increasing intervals during ingestion (Prog) and swallowing at variable intervals (Irreg). These patterns did not differ significantly according to sex. In P2 the increase in volume swallowed increased the duration (dm) of the signal for water (600 msec for 5 ml and 960 msec for 15 ml). The dm for yoghurt was significantly less than for water (580 msec for 5 ml and 920 msec for 15 ml). Our technique of recording sounds of pharyngeal swallowing is simple, reproducible, and not expensive. It permitted the analysis of each swallow according to volume and consistency and the determination of three swallowing patterns (Reg, Prog, and Irreg), taking into account the spontaneous swallowing interval. Ingestion by successive swallows could be used to characterize certain pharyngoesophageal motor dysfunctioning in relation to this reference population and to integrate this into a deglutition rehabilitation program.     

Intra- and Interrater Variation in the Evaluation of Videofluorographic Swallowing Studies

The objective of this study was to determine the inter- and intrarater reliability in evaluating videofluoroscopic swallowing studies (VFSS). Participants included 4 physicians (3 physiatrists and 1 internist) and 5 speech-language pathologists with at least 5 years experience in evaluating VFSS. The main outcomes of the study were reliability ratios of positive and negative tests in inter- and intrarater evaluations. Raters independently rated each of 20 VFSS on two separate occasions. Traits evaluated included oral stage impairment, aspiration, pharyngeal retention, and several functional components: timing of swallow onset, adequacy of velopharyngeal apposition, laryngeal elevation, epiglottic tilt, pharyngeal contraction, and pharyngoesophageal (PE) segment opening. Reliability varied widely depending on food type and the trait under evaluation. Inter- and intrarater reliability ratios did not differ widely. Reliability ratios values typically were highest (greater than 90%) for aspiration, especially with solid food, and lowest for the functional components. It was concluded that inter- and intrarater reliability in VFSS are adequate for evaluating oral stage, laryngeal penetration, and aspiration and pharyngeal retention, but questionable for functional components.     

A Study of Interrater Reliability when Using Videofluoroscopy as an Assessment of Swallowing

Videofluoroscopic assessment of swallowing is widely used in clinical settings. The interpretation of such assessments depends on subjective visual judgments but the reliability of these judgments has been poorly researched. This study measured interrater reliability of judgments, made by speech pathologists, of videofluoroscopic images of subjects swallowing liquid and semisolid boluses. A 5-point rating scale was used in three conditions: individually after careful reading; together with other speech pathologists in group discussion; and individually after the group discussion. Analysis of the ratings for the three conditions revealed that the level of agreement among raters was generally higher for semisolid swallows than for liquid swallows. The highest levels of agreement occurred for ratings made after group discussions. The levels of agreement were lowest when raters worked alone, relying only on reading the scale. Individual rating after group discussion resulted in higher levels of agreement than sole reliance on reading the scale. Factors influencing the levels of interrater agreement, including the timing of observations, bolus consistency, the quality of the image, and the complexity of the task, are discussed.     

Learning about the Dynamic Swallowing Process Using an Interactive Multimedia Program

The management of dysphagia is the largest recognized subspecialty in the field of speech-language pathology. Practicing speech-language pathologists require a comprehensive theoretical and functional knowledge base to underpin the safe and effective management of people with dysphagia. Students need to develop an understanding of the normal integrated swallow and how it can be affected to appreciate the assessment or treatment of dysphagia. Although students are well motivated to learn this material, assimilating knowledge of the dynamic nature of the swallow has typically been problematic because of its complex character. The limitations of currently available teaching resources have been addressed by the production of an interactive multimedia program that includes integrated presentation of text, graphics, voice-overs, and video and animation sequences to highlight various aspects of the swallowing process. Students can selectively manipulate parts of this process to understand the normal swallow and to simulate different aspects of dysfunction and the consequent effects on swallow safety and efficiency. Feedback from students, faculty, and experts has demonstrated that The Dynamic Swallow would be a valued tool in the teaching of dysphagia.     

Fiberoptic Endoscopic Evaluation of Swallowing with Sensory Testing (FEESST) in Healthy Controls

The purpose of this study was to introduce a new method of bedside assessment of both the motor and sensory components of swallowing called fiberoptic endoscopic evaluation of swallowing with sensory testing (FEESST). This approach combines the established bedside endoscopic swallowing evaluation with a more recently described technique that allows objective determination of laryngopharyngeal (LP) sensory discrimination thresholds by delivering air pulse stimuli to the mucosa innervated by the superior laryngeal nerve via a flexible endoscope. A prospective study was conducted of FEESST in 20 healthy control subjects, mean age of 34 ± 11 years. LP sensory thresholds were defined as either normal (<4.0 mmHg air pulse pressure [APP]), moderate deficit (4.0–6.0 mmHg APP), or severe deficits (>6.0 mmHg APP). Subsequent to LP sensory testing, food of varying consistencies, mixed with green food coloring, was given and attention was paid to spillage, laryngeal penetration, pharyngeal residue, aspiration, and reflux. Therapeutic maneuvers such as postural changes and airway protection techniques were performed on each subject to determine if the assessed swallowing parameters were affected by maneuvers. All patients completed the study; all had normal LP sensory discrimination thresholds (2.9 ± 0.7 mmHg APP). There were no instances of spillage, laryngeal penetration, or aspiration. Two of 20 subjects had pharyngeal residue and 2 of 20 had reflux. Institution of therapeutic maneuvers resulted in a predictable change in the endoscopic view of the laryngopharyngeal anatomy. FEESST provides comprehensive, objective sensory and motor information about deglutition in the bedside setting and might have implications for the bedside diagnosis and management of patients with dysphagia.     

Food Transport and Bolus Formation during Complete Feeding Sequences on Foods of Different Initial Consistency

Food movements during complete feeding sequences on soft and hard foods (8 g of chicken spread, banana, and hard cookie) were investigated in 10 normal subjects; 6 of these subjects also ate 8 g peanuts. Foods were coated with barium sulfate. Lateral projection videofluorographic tapes were analyzed, and jaw and hyoid movements were established after digitization of records for 6 subjects. Sequences were divided into phases, each involving different food management behaviors. After ingestion, the bite was moved to the postcanines by a pull-back tongue movement (Stage I transport) and processed for different times depending on initial consistency. Stage II transport of chewed food through the fauces to the oropharyngeal surface of the tongue occurred intermittently during jaw motion cycles. This movement, squeeze-back, depended on tongue–palate contact. The bolus accumulated on the oropharyngeal surface of the tongue distal to the fauces, below the soft palate, but was cycled upward and forward on the tongue surface, returning through the fauces into the oral cavity. The accumulating bolus spread into the valleculae. The total oropharyngeal accumulation time differed with initial food consistency but could be as long as 8–10 sec for the hard foods. There was no predictable tongue–palate contact at any time in the sequence. A new model for bolus formation and deglutition is proposed.