Table 2.
Observational Studies Measuring Spontaneous Swallow Frequency in Patients with, or at Risk of Developing, Dysphagia.
| Author, year | Aetiology | N | Sub-group | Swallow rate (/min) | p | Additional details | Swallow identification method |
|---|---|---|---|---|---|---|---|
| Crary et al. (2014) | Stroke, known dysphagia | 26 | Dysphagia | 0.23 (±0.15) | <0.0001 | Acute stroke patients screened using SSF (via acoustic analysis) vs. standard clinical screening protocols for dysphagia identification | Microphone taped lateral inferior to the cricoid and connected to a digital recorder (Crary et al., 2013) |
|
Stroke, n o dysphagia |
36 |
High-risk |
0.55 (±0.3) |
||||
| Niimi et al. (2018) | Stroke, high SP | 17 | High-risk | 0.51 ± 0.34 | 0.016 | To determine the relationship between SSF and salivary substance p (SP) levels. SP is known to act as a neurotransmitter in the swallowing reflex. Low levels of SP in saliva attenuate the swallowing reflex. SSF data collected for 1-hr per condition | Microphone placed onto the anterolateral side of the neck |
| Stroke, low SP |
23 |
High-risk |
0.27 ± 0.19 |
||||
| Murray et al. (1996) | Older, hospitalised, full cohort | 47 | N/A N/A N/A |
0.89 (±0.85) | Investigation of SSF in the predication of aspiration of food and liquid, following dysphagia categorisation using fiberoptic endoscopic evaluation of swallowing (FEES) | Fiberoptic endoscopic evaluation of swallowing (FEES) | |
| Older, hospitalised, aspiration | 29 | 0.72 (±0.78) | |||||
| Older, hospitalised, no aspiration | 18 | 1.16 (±0.91) | |||||
| Older, normal |
17 |
N/A 2.82 (±1.71) |
|||||
|
Young, normal |
5 |
N/A 2.96 (±0.88) |
|||||
| Crary et al. (2013) | Older, normal | 11 | Healthy old | 0.47 | <0.0001 | To evaluate an acoustic recording technique as a measure to estimate SSF. No significant differences in spontaneous swallow frequency were observed between the multichannel physiologic recordings and the acoustic recordings (0.85 vs. 0.81 sw/min) | Multichannel recordings including surface EMG, swallow apnoea and cervical auscultation. Microphone for acoustic recordings attached just below the lateral cricoid cartilage |
|
Young, normal |
18 |
Healthy yng |
1.02 |
||||
| Tanaka et al. (2013) | Older, normal | 20 | Healthy old | 0.16 (±0.08) | 0.023 | SSF in older people during daily life: a comparison of (1) older persons versus young, and (2) older bedridden versus older semi-bedridden. Recorded for 1-hr each time | Laryngeal microphone and digital voice recorder |
| Bedridden | 10 | High-risk | 0.11 (±0.06) | ||||
|
Semi-bedridden |
10 |
Healthy old |
0.2 (±0.09) |
||||
| Young, normal | 15 | Healthy yng | 0.68 (±0.33) | <0.0001 | |||
| Trocello et al. 2015 | Wilson's disease, dysphagic | 2 | N/A | 0.97 | >0.05 | Examination of hypersialorrhea in Wilson’s disease and association with dysphagia severity. SSF recorded for 10 mins | Stethoscope attached to the neck and a microphone connected to a rhinolaryngeal stroboscope |
| Wilson's disease, non-dysphagic | 6 | N/A | 1.35 | ||||
|
Young, normal |
10 |
Healthy yng |
1.70 |
||||
| Kamarunas et al. 2019 | Oropharyngeal dysphagia, post-CVA | 9 | Dysphagia | 0.73 (±0.75) | 0.48 | Group comparisons on SSF without vibration intervention. Data used as baseline information for study aiming to evaluate whether sensory stimulation could excite an impaired swallowing system (via use of SSF) | 1) Hyolaryngeal elevation (piezoelectric accelerometer peaks) 2) respiratory apnoea (inductive plethysmography - absence of ribcage/abdomen movement) 3) note from trained observer |
| Oropharyngeal dysphagia, post-radiation for H&N cancer | 4 | Dysphagia | 0.7 (±1.15) | ||||
|
Healthy control |
10 |
N/A |
Taken from Mulheren and Ludlow (2017) |
||||
| Pehlivan et al. (1996) | Parkinson’s | 21 | Parkinson’s | 0.8 | <0.05 | Use of “Digital Phagometer” (piezoelectric sensor and digital event counter) to measure SSF in patients with Parkinson’s | Piezoelectric sensor placed at the coniotomy region between the thyroid and cricoid cartilages |
|
Healthy control |
21 |
Healthy yng |
1.18 |
||||
| Marks and Weinreich (2001) | Parkinson’s | 28 | Parkinson’s | 0.55 (±0.32) | Use of an electret microphone to measure SSF to give an indication of drooling in patients with Parkinson’s | Microphone positioned over the centre of the cricoid cartilage | |
|
Healthy, age-matched control |
8 |
Healthy old |
0.13 (±0.03) |
||||
| Kalf et al. (2011) | Parkinson’s, droolers | 15 | Parkinson’s | 0.51 (±0.39) | 0.346 | Factors potentially contributing to drooling, including SSF, examined in Parkinson’s patients with and without diurnal saliva loss | EMG, motion sensor (at larynx) and video |
|
Parkinson’s, non-droolers |
15 |
Parkinson’s |
0.4 (±0.26) |