Table 3.
Review of six research studies investigating the significant differences in voluntary swallowers in dysphagic populations including Stroke, Parkinson’s disease, and Amyotrophic cough measures between unsafe (penetrators and/or aspirators) and safe (non-aspirators) Lateral Sclerosis
| First author year | Patient population Number of participants (N) Swallowing safety groups |
Swallowing assessment method Testing stimuli Statistical comparison |
Significant outcomes: summary of results |
|---|---|---|---|
| Smith-Hammond et al. (2001) [25•] | Stroke N = 43 Stroke; 18 control Three airway safety groups: Severe aspirators (asp’ on all bolus trials) Mild aspirators (asp’ on one or two bolus consistencies) Non-aspirators (no asp’ across trials) |
VFSS or FEES (group n is not specified) 5 mL, 15 mL, and unregulated cup sips of thin liquid, ensure plus, and ‘thickened liquid’ (250–300 cP). (Liquid prepared to match available drinks to inpatients) Between groups comparison (severe aspirators vs. non-aspirators) |
Severe aspirators (vs. non-aspirators) demonstrated the following: Lower peak inspiratory flow rate (770.60 vs. 1120 mL/s) Lower peak expiratory flow rate (−875.13 vs. −1,884.14 mL/s) Higher expiratory rise times (0.34 vs. 0.09 s) Lower cough volume acceleration (5.49 vs. 27.84 mL/s/s) |
| Pitts et al. (2008) [24•] | Parkinson’s disease N = 20 Safe: PAS score 1 Unsafe: PAS score 2–8 |
VFSS 30 mL liquid Between groups comparison (safe vs. unsafe) |
PD patients with unsafe PD swallowing demonstrated the following: Longer compression phase durations (0.36 vs. 0.16 s) Higher expiratory rise times (0.41 vs. 0.21 s) Lower peak expiratory flow rate (6.17 vs. 8.94 L/s) Lower cough volume acceleration (17.02 vs. 45.24 L/s/s) |
| Smith-Hammond et al. (2009) [30] | Stroke N = 96 Non-aspirators: PAS score 1–4 Aspirators: PAS score 5–8 |
VFSS (n = 91) or FEES (n = 5) Pearson correlation coefficient to determine associations between aspiration risk (PAS ≥ 5) and objective cough measures |
Stroke patients who aspirated demonstrated the following: Lower inspiration phase volume (0.45 vs. 0.69 L) Lower inspiration peak flow (−0.82 vs. −1.44 L/s) Lower peak expiratory flow rate (1.98 vs. 5.62 L/s) Higher expiratory rise times (161.50 vs. 14.05 ms) Lower cough volume acceleration (23.49 vs. 136.15 L/s/s) |
| Pitts et al. (2010) [29•] | Parkinson’s disease N = 58 Safe: PAS score 1 Unsafe: PAS score 2–8 |
VFSS 30 mL liquid Receiver operator characteristic analysis |
Discriminant ability of voluntary cough airflow measures to detect penetration/aspiration: Compression phase duration: CP: 0.2 s, sensitivity: 95.8 %, specificity: 64.7 %, LR: 2.7, AUC: 0.83 Expiratory phase rise time: CP: 70.8 ms, sensitivity: 70.8 %, specificity: 64.7 %, LR: 2.7, AUC: 0.71 Expiratory phase peak flow: CP: 7.5 L/s, sensitivity: 87.5 %, specificity: 50 %, LR: 1.8, AUC: 0.69 Cough volume acceleration: CP: 84.5 s/s, sensitivity: 54.5 %, specificity: 97.1 %, LR: 18.4, AUC: 0.72 |
| Hegland et al. (2014) [26•] | Parkinson’s disease N = 40 Safe: PAS score 1–2 Unsafe: PAS score 3–8 |
VFSS ~5 mL thin liquid; cup sip thin liquid; two sequential sips thin liquid; spoon-sized pudding bolus; cookie coated in barium Between groups comparison among cough parameters and penetrator/aspirator vs. non-P/A |
On the first cough of the epoch, PD patients with safe vs. unsafe (PAS ≥ 4) swallowing demonstrated the following: Longer compression phase durations (0.45 vs. 0.22 s) Lower peak expiratory flow rates (5.51 vs. 4.19 L/s) Lower amount of air expired during the sequential cough (49 vs. 42 %) |
| Plowman et al. (2016) [16•, 46] | Amyotrophic lateral sclerosis N = 70 Safe: PAS score 1–2 Unsafe: PAS score 3–8 |
VFSS 20 mL liquid Between group comparisons and receiver operator characteristic analysis |
Unsafe ALS patients demonstrated the following: Lower cough volume acceleration (33.21 vs. 103.71 L/s/s) Longer peak expiratory rise times (159.20 vs. 78.80 ms) Lower peak expiratory flow rate (2.88 vs. 5.31 L/s) Discriminant ability of voluntary cough airflow measures to detect penetration/aspiration: Cough volume acceleration: CP: 45.3 s/s, sensitivity: 91.3 %, specificity: 82.2 %, LR: 5.1, AUC: 0.85 Expiratory rise time: CP: 80 ms, sensitivity: 82.6 %, specificity: 73.9 %, LR: 3.2; AUC: 0.81 Peak expiratory flow: CP: 3.98 L/s, sensitivity: 73.9 %, specificity: 78.3 %, LR: 3.4; AUC: 0.78 |
FEES fiberoptic endoscopic evaluation of swallowing; PAS Penetration–Aspiration Scale; VFS: videofluoroscopic swallow study; CP cut point; AUC area under the curve value; PPV positive predictive value, LR likelihood ratios