Acoustic study of pharyngeal swallowing as a function of the volume and consistency of the bolus.

Cervical auscultation is a noninvasive technique for the exploration of swallowing and has been used since the 1960s. The aim of our study was to describe how the volume and consistency of the bolus affect swallowing acoustic sound characteristics in healthy subjects. Twenty-three subjects aged from 20 to 59 years were included (13 women and 10 men). A microphone mounted on a stethoscope chest piece, positioned on the skin on the right side in front of the posteroinferior border of the cricoid cartilage, was used; it was connected to a computer for acoustic recordings. Each subject swallowed 2-, 5-, and 10-ml aliquots of water, yogurt, and mashed potato. Each bolus was administered once, with a period of at least 30 s between each swallow. For each recorded sound, the total duration of the sound and the duration of each sound component (SC) (SC1, SC2, and SC3) and interval (IT1 and IT2) between the SCs were measured. For all records, the average duration of acoustic measures was calculated. Differences according to the volume and the consistency of the swallowed bolus were assessed using Student's t test for paired data. We calculated the percentage of recordings that included each SC. We also compared results between men and women using Student's t test. We successfully interpreted 540 of the 621 (87 %) records. The results indicated that the average total duration of the sound, and especially the average duration of SC2, increased with increasing volume and was greater for mashed potato than for the boluses of other consistencies. SC2 was present in all of the records.

Pharyngeal swallowing sound profile assessed after partial and total laryngectomy.

Recently, we described three components of a normal pharyngeal swallowing sound. The aim of the present study was to identify variations of these components using synchronized acoustic-radiological data in partially laryngectomized (PL) and totally laryngectomized (TL) patients before and after surgery. In this prospective study, from January 2003 to December 2006 we enrolled 14 patients in a PL group and 9 patients in a TL group. A fluoroscopy camera and a microphone were connected to a computer to obtain acoustic-radiological data (25 images/s). The subjects were asked to perform six deglutitions of 10 ml of barium suspension. The average durations of the sound variables were measured before and after surgery. The duration of the preoperative pharyngeal sound was 602 ms in the PL group and 562 ms in the TL group. It was significantly decreased after the TL (296 ms) and was increased after the PL (740 ms). A typical profile of the swallowing sound for each group was obtained. This study allowed us to describe the main variations of the pharyngeal swallowing sound induced by PL and TL. This noninvasive tool could be useful to assess postoperative swallowing function.

Acoustic study of swallowing behaviour in premature infants during tube-bottle feeding and bottle feeding period.

The premature infant has limited ability to integrate the swallowing-breathing cycle during feeding. The aim of this study was to assess the pattern of swallowing between the period of tube-bottle (TBF) and bottle (BF) feeding by means of cervical auscultation in premature infants. Twenty-three premature infants were enrolled (mean gestational age 34.7 +/- 1.7 weeks). Audiosignal recordings were made during TBF and BF with a small microphone set in front of the cricoid cartilage. The following parameters were calculated for 2 min and reported at 1 min: the percentage of time involved in swallowing (ST), the numbers of swallows (SN) and swallowing bursts (SB) and swallowing groups (SG). Individual histograms were established to show the individual pattern of swallowing behaviour and the distribution of groups, bursts and swallows over 2 min. Mean (STm), (SNm), (SBm), (SGm) values were calculated (+/- S.D.). Statistical analysis was used to compare the means and to establish correlations between parameters and curves. (STm), (SNm) and (SBm) increased significantly during BF compared with TBF for all premature infants and during follow-up. The histograms showed that in BF the groups were high in bursts. These findings and the histograms for each infant will allow determination of transition to bottle feeding without risk corresponding to the stage of maturation of swallowing function.

Study of swallowing sound at the esophagogastric junction before and after fundoplication.

INTRODUCTION: Swallowing sounds can be heard in the lower esophagus by xiphoid auscultation. We hypothesize that the xiphoid sound analysis could provide information concerning the integrity of the esophagogastric junction (EGJ), i.e., superposition of the lower esophageal sphincter (LES) and the diaphragm to assess clinical diagnosis of gastroesophageal reflux disease (GERD) and results of Nissen fundoplication (NF). The aim was to evaluate the changes in sound parameters using our acoustic technique after reorganization of the EGJ after NF. METHODS: For 21 patients with GERD and hiatus hernia, two microphones were placed below the cricoid and on the xiphoid cartilages. The frequency and duration of xiphoid sounds, esophageal transit time were calculated. We defined the xiphoid sound as composed of vibration groups separated by periods >100 ms. The number of vibration groups, number of vibrations per group, and interval between groups were also calculated. RESULTS: The xiphoid sound frequency was increased after NF, and the esophageal transit time and xiphoid sound duration were significantly decreased. A significant correlation was found between xiphoid sound duration and LES-diaphragm displacement. The number of vibration groups and interval between groups were reduced after NF. CONCLUSION: The acoustic technique for swallowing revealed the effects of NF upon the dynamic profile of the EGJ. The organization of vibration groups at the EGJ suggested that the passage of the bolus was modified by hiatus hernia, i.e., dissociation between the LES and the diaphragm and regularized by NF. Concomitant acoustic and radiologic study should contribute to better understanding of sound related to EGJ structure and boli.

Origin of the sound components during pharyngeal swallowing in normal subjects.

The aim of this study was to identify the origin of swallowing sound components by using modern techniques that can provide numeric, synchronized acoustic-radiologic data. We enrolled 15 volunteer subjects (10 men and 5 women, average age = 29.5 +/- 8 years) and used an X-ray camera connected to a video acquisition card to obtain synchronized acoustic-radiologic data (25 images/s). The subjects were asked to swallow 10 ml of a barium suspension. Each sound component was associated with a specific position of the bolus and the anatomic structure that was moving. The average duration of the pharyngeal sound was 690 +/- 162 ms. The durations of the laryngeal ascension sound and the laryngeal release sound were significantly different (72 +/- 38 ms and 106 +/- 47 ms, p < 0.001). The upper-sphincter opening sound was present in 100% of the recordings. Its duration was 185 +/- 103 ms and was significantly different from the two other sounds. The duration of the first interval was 108 +/- 44 ms and the duration of the second was 236 +/- 139 ms. This study allowed us to determine the origin of the three main sound components of the pharyngeal swallowing sound with respect to movements in anatomic structures and the different bolus positions.

Sound component duration of healthy human pharyngoesophageal swallowing: a gender comparison study.

Cervical auscultation is a noninvasive technique for studying swallowing that was first used in the 1960s. The aim of our study was to use the numeric acoustic recording technique for analyzing swallowing sound signals in healthy subjects while they ingested a defined volume and consistency of a specific substance. Twenty males and ten females were included in the study and given 10 ml of a barium suspension to swallow. A microphone was placed on the skin overlying the lateral border of the trachea, directly under the inferior border of the cricoid, and connected to a computer. For each sound recording, the total duration of the sound (td), the number (n) of sound components (SC), the duration of each SC (c1, c2, c3,...), and the intervals (i1, i2,...) between the SCs were measured. For all the recordings, the mean durations of acoustic parameters (TDm, C1m, C2m, C3m, I1m, I2m) were calculated and compared by using Student's t test. In the 20 male subjects, the mean acoustic parameters were calculated (MTDm, MC1m, MC2m, MC3m, MI1m, MI2m) and compared with the mean acoustic parameters (FTDm, FC1m, FC2m, FC3m, FI1m, FI2m) in the ten females by using a Wilcoxon nonparametric statistical test. We were able to interpret 80% of the recordings. The TDm was 710 +/- 28 ms. Three main SCs were detected: C1m = 100 +/- 56, C2m = 150 +/- 90, C3m = 80 +/- 54 ms; I1m = 100 +/- 66, I2m = 190 +/- 120 ms. No significant difference in these parameters was observed with respect to gender. This study enabled us to decompose the swallowing sounds into three main SCs and to quantify their normal durations. These results should prove useful for the assessment of sound variations in pathologic conditions.