Measurement Of Objective Parameters Associated With Pharyngeal Swallowing Function In Chinese Adults

Background:Swallowing is an extremely complex physiological process of reflex, which is divided into oral, pharyngeal and esophageal stages. Slight dysfunction of each stage can lead to swallowing problems or disorders. Oral stage is to bring the bolus to the palate and stimulate the peripheral nerve receptor in the soft palate, palatopharyngeal arch and tongue base, which triggered the next stage-the pharyngeal stage. Pharyngeal stage is a series of involuntary reflex physiological activities, including the velopharyngeal valve close, faucial close and airway close to avoid the bolus to the nasopharynx, oral cavity and airway, and also including the pharyngeal wall contraction, the elevation of the hyoid bone and the larynx and the cricopharyngeal opening, that propel the bolus to the esophagus safely. The esophageal stage moves the bolus to the stomach through the esophageal peristalsis. The oral pharynx is the common passage of the breathing air and swallowing food. In the pharyngeal stage of swallowing, coordination of the breathing and swallowing is a complex process and is a very precise action. During the swallowing, the airway must be precisely and completely closed, in order to ensure that food is not being diverted to the airway, so pharyngeal stage is very important in the process of swallowing.In recent years, with the further study of dysphagia, it was found that the population incidence of dysphagia is very high. A report on the survey of the aged people found that87%of the elderly had the eating problems in different degrees, of which68%had obvious swallowing disorders,46%had oral feeding difficulties, and35%had a poor eating posture. Dysphagia can cause aspiration pneumonia, malnutrition, dehydration and other complications, which seriously affect the patients’ quality of life, and even lead to death. After years of development, dysphagia has become a highly important issue of the medical field. But the study of swallowing is not very popular in our country. Current clinical assessment of swallowing function and diagnosis of dysphagia, such as the bedside water testing and repeated saliva swallowing test, are based on the patients’clinical symptoms and subjective feelings. The sensitivity and specificity of each report is quite different.Fiberoptic endoscopic evaluation of swallowing can observe the anatomical structures of the throat. It not only could assess the patients’swallowing function by swallowing different viscosity foods with edible pigment, but also could assess the laryngeal sensory function by jet different pressure pulse airflow to the arytenoids through the endoscopic biopsy hole. It can be used for different degree patients, even can be used for patients in ICU. Fiberoptic endoscopy can find all the lesions such as edema, granuloma, ulcer, vocal cord paralysis and stenosis of the larynx, it can only observe the larynx, hypopharynx, but it can not see the whole process of the swallowing. Because when swallowing, the pharynx closed, endoscopic vision disappeared, so we just can evaluate the changes before and after swallowing.Videofluorographic swallowing study is the best method for examination of the swallowing process, because it can observe the whole process of swallowing. It can find the subtle abnormal changes in swallowing movements, and distinguish swallowing disorders caused by structural abnormalities from functional abnormalities. Dynamic swallow study developed on this basis, which overcome some of its disadvantages. With the further application of computer technique and image management software, foreign experts applied computer technique and image measurement software to the process of swallowing by analyzing the swallowing videos frame by frame and found some objective parameters associated with pharyngeal swallowing function such as maximum displacement of the hyoid bone (HmaxD), pharyngeal transit time (PTT), pharyngeal constriction ratio (PCR) and maximum opening of the esophageal entrance (EEmax). Now foreign experts have established an assessment system through the dynamic swallow study, which had a more accurate judgment on the diagnosis and treatment of swallowing disorders. Compared with the normal data associated with pharyngeal swallowing function, we can get the abnormalities of the patients with swallowing problems more precisely. We can begin management the dysphagia of the patients based on the assessment results. This work has not been carried out in our country. In this study, we use dynamic swallow study method and obtained a series of objective parameters associated with pharyngeal swallowing function in Chinese adults.Objectives:To obtain a series of objective parameters associated with pharyngeal swallowing function using dynamic swallow study in Chinese adults.Methods:Eighty healthy adult volunteers were recruited and informed consent was signed. Dynamic videofluoroscopic swallow study was performed on all the volunteers in Department of Radiology of Navy General Hospital. The study was approved by the Navy General Hospital Ethics Committee. There were40males and40females with an age ranged from20to60years old. There were no swallowing diseases and diseases affecting swallowing function in volunteers. All the men and women volunteers were divided into two groups:age<40years as group1and age^40years as group2. There were19subjects and16subjects in male and female group1respectively, and21subjects and24subjects in male and female group2respectively.Shimadzu digital gastrointestinal machine, HORITA time recording and digital video recorder were used. The fluoroscopy is done in the upright position with the lateral view of the pharynx. The subjects take a bolus of60%barium sulfate suspension (20ml) for one swallow. The whole process of the swallow is recorded. The structures that are visualized include the base of the tongue, valleculae, epiglottis, pyriform sinuses, cricopharyngeal muscle and the cervical esophagus. The recording of the swallowing process were analyzed frame-by-frame through Avidemux2.5software and Image J measurement software. Finally we measured each subject’s HmaxD, PTT, PCR and EEmax.Maximum displacement of the hyoid bone (HmaxD):Hmaxd is defined as the distance traveled by the hyoid bone to the point of maximal elevation during swallow from its position before swallowing. The image of the hyoid bone before swallowing is saved. Then the video of swallowing was analyzed frame by frame to find the image of the hyoid bone moved to its maximum superior-anterior displacement position and saved using Avidemux2.5software. The anterior and inferior border of the hyoid bone was outlined and a90°angle was drawn out along the anterior border of the C3-C6cervical vertebrae and inferior border of the C6cervical vertebrae on the two images saved above using Image J software. Selection was made containing the portion of hyoid bone and the portion of90°angle on vertebrae on the first image and this part of the image selected was copied and pasted to the second image. The right angle from the two frames should be aligned completely in the second image. The diameter of a dime (1.9cm) placed under the submentum of the subjects was used as the reference length. The distance between the anterior parts of the two hyoid bones was measured using Image J software and the distance is the HmaxD.Pharyngeal transit time(PTT):PCR is defined as the total time of the bolus passage through the pharynx. HORITA time recorder can be accurate to0.01s on the video frame. The images of the first movement of the head of the bolus past the posterior nasal spine and the moment that the tail of the bolus past the pharyngoesophgeal sphincter and fully within the esophagus were saved. The time difference between two images is the PTT.Pharyngeal constriction ratio(PCR):The PCR is defined as the ratio of the pharyngeal area measured in the lateral view at its point of maximum constriction during swallow to the pharyngeal area measured before swallow. The images of the lateral view of the pharynx before swallow and the image at the point of maximum constriction during swallow were saved. The two dimensional area of the pharynx at the two images was measured using Image J software. The PCR was calculated using the formula:[(pharyngeal area before swallow-maximum constriction pharyngeal area)/pharyngeal area before swallowx100%].Maximum opening of the esophageal entrance(EEmax):EEmax is defined as the greatest expansion of the esophageal entrance during swallow. The image of the greatest expansion of the esophageal entrance during swallow was saved and the distance of the esophageal entrance was measured using Image J software, which is the EEmax.Statistical methods:The data of the parameters measured was inputted into a computer to establish a database for statistical analysis using SPSS16.0. Measurement data obtained showed a normal distribution and homogeneity of variance. Group differences were tested using the t test with mean±standard deviation (x±s), P<0.05for the difference was statistically significant.Results:In the80adults, the HmaxD, PTT, PCR, and EEmax were (1.91±0.48)cm,(0.82±0.15)s,94.9%±3.41%, and (0.91±0.05)cm respectively. The95%confidence limits of HmaxD, PTT, PCR, and EEmax were1.14～2.94cm,0.50～1.12s,86.9%～100.0%and0.82～1.02cm in male subjects respectively, and0.88～2.68cm,0.70-0.96s,89.5%～100.0%,0.81～1.01cm in female subjects respectively. The HmaxD of the male (2.04～0.46)cm was significantly larger than that of the female (1.78±0.47) cm (t=2.44, P=0.017), but the PTT, PCR, and EEmax had no significant difference between different gender and age groups (P>0.05).Conclusion:Objective parameters of the HmaxD, PTT, PCR, and EEmax during swallowing are obtained in Chinese adults. These data are very important for assessment of the swallow function and provide a foundation for further research on assessment of swallowing function in Chinese adults.