Effects of sitting posture and bolus volume on activation of swallowing-related muscles

Chewing Well Modulates Pharyngeal Bolus Transit During Swallowing in Healthy Participants

Mastication is controlled by central pattern generator in the brainstem and can be modulated by volition. The aim of this study was to investigate the effect of chewing well on swallowing. Twenty-six healthy participants were instructed to eat 8, 12, and/or 16 g of steamed rice with barium sulphate under the following two conditions: chewing freely task (CF; chewing naturally in their usual manner) and chewing well task (CW; chewing the food with a request to "chew well"). We evaluated bolus transport and swallowing movement using videofluoroscopy and electromyography of the masseter, suprahyoid and thyrohyoid muscles. The chewing time and pharyngeal transit time (PTT) at the first swallow showed high reproducibility in both CF and CW. PTT for CW was significantly shorter and longer than CF in 12 and 16 g, respectively. In 12 g, CW increased the pharyngeal bolus velocity and decreased thyrohyoid EMG activity during swallowing compared with CF. In 16 g, the difference between CW and CF in the estimated swallowed bolus volume was positively correlated with that in upper esophageal sphincter transit duration. We speculate that CW modulates PTT during swallowing depending on the mouthful volume.

Influence of Spinal Sagittal Alignment in Sitting Posture on the Swallowing Speed of Older Adult Women: A Cross-Sectional Study

Thoracolumbar kyphosis in sitting posture is associated with forward head posture and may adversely affect swallowing function. However, few studies have investigated the effect of spinal alignment in the sitting posture on the swallowing function of older adults. This cross-sectional study aimed to investigate whether spinal alignment in the sitting posture influences the swallowing function of older adult women. Overall, 18 older adult women (mean age, 69.78 ± 3.66 years) without dysphagia were enrolled. Participants were positioned in two sitting postures, namely, comfortable sitting (CS) and thoracic upright sitting (TUS). In each sitting posture, the kyphosis index (using a flexicurve), sagittal angles (head, cervical, shoulder, and pelvic angles; using a digital camera), and cervical range of motion (ROM) were evaluated. Swallowing speed (100-mL water swallowing test), maximum tongue pressure (MTP), and oral diadochokinesis (ODK) were also evaluated. Compared with TUS, CS showed a greater kyphosis index, anterior head translation, and posterior pelvic tilt. CS had greater flexion (p < 0.001) and less extension (p < 0.001) of cervical ROM than TUS. Swallowing speed was significantly decreased in CS compared with TUS (p = 0.008). MTP and ODK were not significantly different between CS and TUS. Thus, changes in sitting posture with spinal alignment may affect swallowing speed. Consequently, adjustments to reduce sitting postural kyphosis in older adult women may improve swallowing speed.

Ultrasonographic measurements of the omohyoid muscle during shoulder muscles contraction

BACKGROUND

The main function of the omohyoid muscle is to depress and withdraw the hyoid bone. This is an integral part of the swallowing process facilitating hyoid stabilization for tongue movement. Although the muscle is inferiorly attached to the scapula bone, its function during shoulder or scapula muscles contraction has yet not been studied.

AIM

To investigate whether changes occur in omohyoid muscle morphology during shoulder muscles contraction.

METHODS

The study included 40 healthy subjects (20 males and 20 females, Mean age: 25.68 (± 2.90) years) examined via diagnostic ultrasound. Omohyoid muscle morphology measurements (thickness and cross-sectional area) during different shoulder position (0°, 90° abduction and elevation) in rest and during isomteric contraction were evaluated.

RESULTS

The omohyoid muscle was activated when the shoulder was isometrically abducted at 90° abduction. Thickness and the cross-sectional area of the lower belly increased during contractions at 90° abduction compared with a resting position at 90° (p value < 0.01). No changes occurred at 0° isometric abduction. The CSA of the muscle was found to be significantly larger (p < 0.001) during contraction at 90° abduction compared with contraction at 0° abduction.

CONCLUSION

Omohyoid muscle was most contracted during abduction position with abduction shoulder muscles isometric contraction. Changes of the scapula position might influence omohyoid muscle function.

Strategies of Screening and Treating Post-Extubation Dysphagia: An Overview of the Situation in Greek-Cypriot ICUs

Post-extubation dysphagia (PED) can lead to serious health problems in critically ill patients. Contrasting its high incidence rate of 12.4% reported in a recent observational study, many ICUs lack routine bedside screening, likely due to limited awareness. This study aimed to establish baseline data on the current approaches and the status of perceived best practices in PED screening and treatment, as well as to assess awareness of PED. A nationwide cross-sectional, online survey was conducted in all fourteen adult ICUs in the Republic of Cyprus in June 2018, with a 100% response rate. Over 85% of ICUs lacked a standard screening protocol for PED. The most commonly reported assessment methods were cough reflex testing and the water swallow test. Treatment approaches included muscle strengthening exercises without swallowing and swallowing exercises. Only 28.6% of ICUs acknowledged PED as a common issue. The study identified significant gaps in awareness and knowledge regarding PED screening and treatment in Greek-Cypriot ICUs. Urgent implementation of comprehensive dysphagia education programs within the units is necessary, and interdisciplinary collaboration among nurses, intensivists, and speech and language therapists is crucial to improve the quality of care provided.

Effect of Spinal Sagittal Alignment in Sitting Posture on Swallowing Function in Healthy Adult Women: A Cross-Sectional Study

Swallowing function is both directly and indirectly related to postures, such as head and cervical angle and body position. However, the effects of different sitting postures on oropharyngeal swallowing have not been investigated. This study aimed to investigate whether the change in thoracolumbar alignment affected the oropharyngeal swallowing. A total of 58 healthy adult women (mean age 22.2 ± 1.67 years) without dysphagia were enrolled in this cross-sectional study. Participants were positioned in three sitting postures: comfortable sitting (CS), thoracic upright sitting (TUS), and slump sitting (SS). In each sitting posture, the kyphosis index (using a flexicurve), head and cervical angles (using a digital camera), swallowing speed (100-ml water swallowing test), and oral and articulatory function [by maximum tongue pressure (MTP) and oral diadochokinesis (ODK)] were evaluated. SS showed the largest kyphosis index and was associated with a greater anterior translation of the head. Swallowing speed was significantly decreased in SS compared with CS (p = 0.002) and TUS (p = 0.020) and ODK was significantly decreased in SS compared with other postures, for both /ta/ (p = 0.004) and /ka/ (p < 0.001) syllables. Further, MTP tended to decrease in SS compared with TUS (p = 0.064). Our results suggest that changes in sitting posture with different thoracolumbar alignments affect swallowing speed and oral and articulatory function. Consequently, adjustments to reduce sitting postural kyphosis may improve swallowing speed and oral and articulatory function.

Noninvasive Evaluation of the Biomechanical Accommodations to Bolus Volume during Human Swallowing

Bolus volume is very important in the biomechanics of swallowing. By noninvasively characterizing swallow responses to volume challenges, we can gain more knowledge on swallowing and evaluate swallowing behavior easily. This study aimed to evaluate the impact of bolus volume on the biomechanical characteristics of oropharyngeal swallowing events with a noninvasive sensing system. Fifteen healthy male subjects were recruited and instructed to swallow 5, 10, and 15 ml of water. The sensing system consisted of a tongue pressure sensor sheet, bend sensor, surface electrodes, and a microphone. They were used to monitor tongue pressure, hyoid activity, surface EMG of swallowing-related muscles, and swallowing sound, respectively. In addition to the onset, the peak time and offset of the above four structures, certain characteristics, such as the duration, peak value, and interval of the structure motions, were measured during the different drinking tasks. The coordination between the hyoid movement and tongue pressure was also assessed. Although no sequence of the structural events changed with volume, most of the timings of the structural events were significantly delayed, except for certain hyoid activities. The swallowing volume did not affect the active durations of the monitored structures, the peak values, or intervals of tongue pressure and supra- and infrahyoid muscle activity, but certain hyoid kinetic phases were prolonged when a larger volume was swallowed. Additionally, sequential coordination between hyoid movement and tongue pressure was confirmed among the three volumes. These findings suggest that oropharyngeal structural movements change in response to bolus volume to facilitate safe swallowing. The noninvasive and quantitative measurements taken with the sensing system provide essential information for understanding normal oropharyngeal swallowing.