Abstract
Objective. To evaluate the effect of effortful swallow on pharyngeal pressure while swallowing saliva and water using a novel high-resolution manometry (HRM) system.
Study Design. Case series with planned data collection.
Setting. Nagasaki University Hospital.
Subjects and Methods. Eighteen asymptomatic Japanese adult volunteers were studied. A solid-state HRM assembly with 36 circumferential sensors spaced 1 cm apart was positioned from the velopharynx to the upper esophagus to record pressures while swallowing. The maximum values of the pressure while swallowing saliva (dry swallowing) and 5 mL of water were measured at the velopharynx, meso-hypopharynx, and upper esophageal sphincter (UES) with and without effortful swallows.
Results. The maximum values of dry swallowing pressures (mm Hg) at the velopharynx, meso-hypopharynx, and UES were significantly higher with effortful swallow (155.7 ± 59.7, 256.7 ± 78.7, and 276.5 ± 87.5, mean ± standard deviation) than without it (115.3 ± 60.8, 172.9 ± 57.0, and 195.8 ± 61.3). Those of water swallowing pressures were also statistically higher with effortful swallow (169.3 ± 69.1, 236.6 ± 77.2, and 267.3 ± 79.1) than without it (119.2 ± 59.7, 189.5 ± 70.7, and 221.3 ± 72.7).
Conclusion. The present results provide quantitative evidence of effortful swallow as well as physiological information. It also is hoped to be an aid to future clinical and investigative studies.
Keywords
Several swallowing maneuvers targeted toward either compensation for the disorder or restitution of impaired function are applied in the management of swallowing disorders. 1 Among those maneuvers, effortful swallow is a behavioral technique that is used in the rehabilitation of individuals who have swallowing impairment, or dysphagia. By instructing the patient to “squeeze hard with all your muscles as you swallow,” the effortful swallow is designed to increase contact between the tongue base and posterior pharyngeal wall while swallowing. 2 Although several studies have investigated the effortful swallow to elucidate its effect on swallowing biomechanics and its potential for facilitating pharyngeal bolus propulsion, the results from these studies were conflicting. Using conventional manometry, some studies demonstrated that the pharyngeal pressure increased with effortful swallowing, 3-5 whereas another documented only a minor decrease of peak pharyngeal pressure measured at the level of the inferior pharyngeal constrictor, found in the effortful swallow versus the noneffortful swallow in all the participants. 6
Characteristics of pharyngeal swallowing have been quite difficult to study using conventional manometry. That is because the movement of the soft palate and the elevation of the larynx while swallowing cause a spike-like movement along the velopharynx and upper esophagus. Also, it is extremely difficult to detect the exact pressure of a specific point by analyzing the values with only a few sensors widely spaced about 2 cm or more apart. Advances in computer technology have enabled the large volume of data acquired by novel high-resolution manometry (HRM) to be presented in real time not only as conventional “line plots” but also as “spatiotemporal plots” (sometimes referred to as a “contour” or “topographic” plots). These display the direction and force of esophageal pressure activity. Esophageal HRM is now used for both research and clinical practice. 7 We previously reported the feasibility of the novel HRM system for evaluating pharyngeal swallowing along the velopharynx and upper esophagus of normal Japanese adults and demonstrated that HRM can overcome those disadvantages of conventional manometric methods. 8,9 The purpose of this study was to quantify the effects of effortful swallow on the pharyngeal pressure in healthy participants using the HRM system and to suggest the feasibility of the effortful swallow maneuver as a rehabilitative procedure for dysphagic patients.
Methods
Subjects
We studied 18 healthy Japanese male volunteers without a history of dysphagia, gastrointestinal symptoms, upper gastrointestinal tract surgery, or significant medical condition. Their ages ranged from 23 to 28 years. The study protocol was approved by the Institutional Review Board Committee of Nagasaki University Hospital, and written informed consent was obtained from each participant.
Measurement Using High-Resolution Manometry
The protocol using the HRM system (ManoScan, Sierra Scientific Instruments, Inc, Los Angeles, California) was described in our previous report in detail. 8 In brief, after local anesthesia in the nasal cavity, the catheter was inserted and fixed by taping at the nostril with the patient in a natural supine position.
Examinees were asked to perform 4 different swallowing conditions: (1) noneffortful dry (saliva) swallow, (2) noneffortful swallow of 5 mL of ice water, (3) effortful dry swallow, and (4) effortful swallow of 5 mL of ice water. For each condition, 3 trials were completed with a 30-second interval between each swallow, and the mean values were adopted. We used ice water (0°C) to keep the conditions of thermal stimulation to the pharynx constant among examinees during the examination.
Manometric data were initially analyzed using ManoView analysis software (Sierra Scientific Instruments, Inc; Figure 1 ). Parameters measured in this study were the maximum value of the swallowing pressures at velopharynx, meso-hypopharynx, and upper esophageal sphincter (UES) regions. The definition of the swallowing pressures at velopharynx, meso-hypopharynx, and UES regions was described in our previous report in detail. In brief, the sites showing the velopharyngeal and meso-hypopharyngeal swallowing pressures were easily identified by vocalizing “kakkakaka.” 8
Using ManoView analysis software, the maximum value of swallowing pressure in mm Hg is demonstrated. A selected area (dotted line) shown in this figure is the velopharyngeal region. The white arrow revealed the maximum value of swallowing pressure in the area.
To evaluate the effect of swallow type (noneffortful vs effortful) and bolus type (saliva vs 5 mL ice water), statistical analysis was made using Wilcoxon signed-ranks test, and P values below .05 were regarded as significant.
Results
On the color-graphic presentation of the HRM system, the red color is deeper and wider with effortful swallow than without the effortful swallow while swallowing, indicating that the swallowing pressure increases and lasts longer with effortful swallow. The blue color in the UES region indicates that the UES relaxes with swallowing ( Figure 2 ). All results in the present study are demonstrated in Figures 3 , 4 , and 5 . During dry swallowing, the maximum values of pressures (mm Hg) at the velopharynx, meso-hypopharynx, and UES regions were significantly higher with effortful swallow (155.7 ± 59.7, 256.7 ± 78.7, and 276.5 ± 87.5, mean ± standard deviation) than without effortful swallow (115.3 ± 60.8, 172.9 ± 57.0, and 195.8 ± 61.3). Those of 5-mL ice-water swallow pressures were also significantly higher with effortful swallow (169.3 ± 69.1, 236.6 ± 77.2, and 267.3 ± 79.1) than without effortful swallow (119.2 ± 59.7, 189.5 ± 70.7, and 221.3 ± 72.7). However, there were no significant differences in the maximum values of pressures between dry and ice-water swallows at any of the 3 regions regardless if the swallow was effortful or noneffortful (P = .255 and P = .723, P = .136 and P = .407, and P = .981 and P = .352, respectively).
Typical change of the color-graphic pattern during dry swallow without (A) and with (B) effortful swallow was demonstrated. The red color during dry swallow pressure was stronger and wider with effortful swallow (B) than without effortful swallow (A). This indicates that the pressure increased and lasted longer with the effortful swallow in all regions. UES, upper esophageal sphincter.
Results of the maximum values of the dry and water swallow pressures with and without the effortful swallow at the velopharyngeal region are demonstrated. Solid circles and bars indicate mean values and standard deviations, respectively.
Results of the maximum values of the dry and water swallow pressures with and without the effortful swallow at the mesohypopharyngeal region are demonstrated. Solid circles and bars indicate mean values and standard deviations, respectively.
Results of the maximum values of the dry and water swallow pressures with and without the effortful swallow at the upper esophageal sphincter region are demonstrated. Solid circles and bars indicate mean values and standard deviations, respectively.
The distances from the nostril to each point of maximum values of swallow pressures with effortful swallow were almost the same as those without effortful swallow at all 3 regions ( Table 1 ).
Distances (cm) From Nostril to Maximum Pressure Point of Velopharynx, Meso-Hypopharynx, and UES Regions
Abbreviation: UES, upper esophageal sphincter.
Discussion
As for effortful swallow, a more thorough investigation of this technique was needed to enable a clearer understanding of the biomechanical changes that occur in response to volitionally altered swallowing behaviors. Some publications have documented increased pressure generation, 3-5 whereas others have reported conflicting results. 6 Because the novel HRM system has been established as one of the most appropriate tools for evaluating pharyngeal swallowing along the pharynx 8,9 and esophagus, 7 we conducted the present study clarifying the effect of effortful swallow pressures using it. To the best of our knowledge, this is the first study to investigate the effect of the effortful swallow pressures among velopharyngeal and UES regions with both dry and water swallows using the HRM system.
In the present study, the maximum values of the pressures with effortful swallows at the velopharynx, meso-hypopharynx, and UES regions increased compared to those without effortful swallows without change of the positions of maximum values at any region in any swallow or any bolus type. The base of the tongue was identified as the main driving force in bolus propulsion, 10,11 and effortful swallow was designed to increase contact between the tongue base and posterior pharyngeal wall while swallowing. 1,2 Therefore, we suppose that the base of the tongue may be a contributor for increased pharyngeal pressure in the meso-hypopharynx regions. We are not able to identify the exact point of the base of the tongue in the meso-hypopharynx regions on HRM.
The pressure increase accompanied by the effortful swallows was observed not only in the meso-hypopharyngeal region but also in the velopharyngeal and the UES regions. This suggests that the pressure increase might be caused also by voluntary stronger contractions of the superior and inferior pharyngeal constrictor muscles. Coulas et al 12 reported that effortful swallowing was linked to increased neck circumference and speculated that it may reflect a number of physiological factors in combination. From the present results, it was suggested that the superior and inferior pharyngeal constrictor muscles, as well as the middle pharyngeal constrictor muscle, may contribute to the increase in pressure in all regions of the pharynx during effortful swallowing by voluntarily constricting more strongly than usual.
In the present study, effortful swallowing revealed active changes in muscular contractions of all 3 regions, including velopharyngeal, meso-hypopharyngeal, and UES in healthy young participants. These results provide us with some of the quantitative evidence of the effortful swallow as an effective rehabilitative measure, as well as its physiological information, and it is hoped that it will be an aid to future clinical and investigative studies. As a next step, clinical extension of this research is needed to investigate the effect of the effortful swallow on patients with reduced base of tongue retraction or pharyngeal constrictor weakness to evaluate if this maneuver is effective for those patients as one of the rehabilitative measures for swallowing disorders.
Conclusion
The present results provide quantitative evidence of effortful swallow as well as physiological information. It is also hoped to be an aid to future clinical and investigative studies.
Author Contributions
Disclosures