A Study of the Differences Between Submental Ultrasonography (SUS) and Assessment by Speech-Language Pathologists (SLP) for Nasogastric Tube Removal
Phase: NA
Conditions: Dysphagia Rehabilitation
Sponsor: National Taiwan University Hospital

 
Official title: A Study of the Differences Between Submental 
Ultrasonography (SUS) and Assessment by Speech-Language 
Pathologists (SLP) for Nasogastric Tube Removal 
NCT number: 202411050RINC 
Document date: December 30, 2025 
 
 

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Study Protocol 
Participants 
The research was performed at the 7th floor Integrated Medicine wards of National Taiwan 
University Hospital from February to December 2025. All 26 Taiwanese patients were stabilized 
acute illness (post-acute) without any nasogastric (NG) tube before this admission and referred to 
our team. The inclusion and exclusion criteria were shown below in Table 1.   
Inclusion criteria 
Exclusion criteria 
Adults aged 18 and above 
Impaired consciousness 
Long-term NG use, before this admission 
Nasogastric (NG) tube use in this admission 
Oxygen mask or mechanical ventilation 
Excessive drooling or frequent aspiration 
Non-stroke stabilized acute illness status 
Oral or head and neck surgery history 
Patient refusal 
Table 1. Inclusion and exclusion criteria 
The submental ultrasonographic examination and speech therapists’ swallowing assessments 
were performed once when the participants agreed to join the study. The Research Ethics 
Committee of National Taiwan University Hospital approved the study protocol and all 
participants provided written informed consent. IRB number: 202411050RINC. 
This study was a randomized controlled trial (RCT), 26 patients with NG agreed to join 
initially. After their agreement, the patients were randomly distributed to either submental 
ultrasonography group (SUS) or speech therapist group (ST). Each two groups would undergo 
submental ultrasound examination and speech therapist’s assessment, but the criteria for entering 
oral feeding training and NG removal will be followed by their group. As the SUS group for 
entering oral feeding training and NG removal, the criteria would be maximum hyoid bone 
displacements over 1.38 cm; while the ST group would base on the speech therapist’s assessment 

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forms to determine pass or fail. If the patients fail to pass the criteria no matter in SUS group or 
ST group, they would undergo routine swallowing rehabilitation and keep NG feeding after 
discharge. The RCT flowchart is showed in Figure 5 .  
Submental ultrasonographic examination and measurement 
Protocol for submental ultrasonographic examination 
Figure 1. RSST and submental ultrasonographic examination 
 
Shown in fig 1, participants were examined in upright position and kept the mandible 
vertical with the neck. First, RSST (repetitive saliva swallowing test) was performed by the 
examiner for initial assessment. (Cut-off value was feeling swallowed motion three times in 
thirty seconds.) (Oguchi et al., 2000) Then, a self-designed water-filled bag (150 ml water in a 
small size glove) was placed on ultrasound probe to keep stable when examined. (as the picture 
shows) Placed the probe in the midsagittal plane in the submental area. Asked patients swallow 
their saliva and recorded the hyoid bone displacement. Repeated three times for each examiner 
to take mean maximum hyoid bone displacement value. 
Images Measurement   
The wireless ultrasound machine used in this study was a LeSono Ultrasound Imaging 
System LU710L (Leltek Inc., New Taipei City, Taiwan) with a 5.0 MHz convex transducer in 
grayscale 2-dimensional mode, in combination with a Galaxy Tab S7 FE 5G SM-T736B 
(Samsung Electronics Co., LTD, Taipei, Taiwan). Record each examination as videos and using 
the internal distance measurement tool in ultrasound image software to measure hyoid bone 

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displacement = distance between the shadows created from the mandible and the hyoid bone (at 
rest, neutral)-(during swallowing). Take the maximum displacement of each assessment. Set cut 
off values, 1.38 cm to determine the patient pass (>1.38cm) or fail (<1.38 cm), which was based 
on our previous pilot study. The examples were in figure 2 and 3. 
 
Figure 2. submental ultrasonographic image and anatomical structures 
 
 
 
 

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Figure 3. Ultrasonographic examples of pass and fail results 
Length Measurement: The green dash-line 
A, C: at rest, neutral position 
B, D: Maximum muscle contraction during swallowing 
 
Fig A, B: Patient passed the criteria 
Maximum displacement(neutral-swallowing) = 5.067-3.365 = 1.702 cm 
Fig C, D: Patient failed to the criteria 
Maximum displacement(neutral -swallowing) = 4.849-3.926 = 0.923 cm 
  
Speech therapists’ swallowing assessments   
Two well-trained, licensed speech therapists were invited to assess the patients’ swallowing 
function using a protocol developed by the Department of Physical Medicine and Rehabilitation 
at National Taiwan University Hospital. The speech therapists first evaluated the patients’ 
cooperation and level of consciousness, followed by an objective examination of the oral-motor 
mechanism, including the lips, cheeks, jaw, and tongue. Next, for the swallowing test, they 
provided small amounts of water or thickened liquids, or asked the patients to swallow their saliva, 
to observe their swallowing performance. Key observations included a prolonged oral phase, 
delayed swallowing reflex, reduced laryngeal elevation, choking, and the presence of a wet voice. 

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Each observation was coded on a 0–2 (impaired to normal) point scale, yielding a total possible 
score of 10. 
Based on these findings, the speech therapists determined whether the patient passed or failed 
the assessment for initiating oral feeding training for NG tube removal. In addition, they provided 
rehabilitation strategies and exercises for the patients. 
Oral feeding training 
Oral feeding training protocol was based on The International Dysphagia Diet Standardisation 
Initiative (IDDSI) framework. Once the patients passed the criteria of their group, they will start 
to try oral feeding training for 2 to 5 days. The protocol was shown in table 2, following the order 
of IDDSI 2 to 4 to 5. After the sixth meal was done, and no chocking occur, NG could be removed. 
If chocking recurred several times, the training would stop and defined as training failure, and the 
patient remained feeding by NG.  
 
Order 
Annotations 
IDDSI 2 
(thicken water) 
100ml① 
200ml② Add Food Thickener 
IDDSI 4 
100ml③ 
200ml④ Adjust tube feeding amount to keep the 
Total Daily Energy Expenditure 
IDDSI 5 
100ml⑤ 
200ml⑥ Remove NG after passing these meals 
without chocking  
Table 2. Oral feeding training protocol 
Statistical analysis Plan 
Method 
All statistical analyses were performed using the SPSS 27 (IBM Corporation, Armonk, NY, 
USA).  Group differences for all parameters were compared using Kruskal-Wallis H test (age, 
gender, GCS, Barthel Index). The correlations of three swallowing evaluation methods, SUS, 
RSST, and SLP assessments were analyzed by Fisher’s Exact Test and Spearman’s rank 
correlation. The mean maximum displacement of hyoid and mandible bone was the predictors for 
swallowing function and swallowing times measured in RSST were all collected to plot the 
receiver operating characteristic (ROC) curve. The optimal cut-off value of the ROC curve was 
determined by Youden index.  

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Flow chart of the trial