Within-group analysis of signs of airway invasion (events)

No eventsYes eventsp-value
TWST for liquids
 Sample size125
 Total time s13.8 (8.1–20.6)27.3 (15.7–41.6)0.114
 Number of swallows7.7±2.4610.8±4.10.067
 Volume per second mL·s−112.5±6.86.2±3.90.073
 Volume per swallow mL21.7±16.915.6±8.50.124
 Time per swallow s1.7 (1.4–2.4)2.2 (2.0–2.6)0.092
TOMASS for solids
 Sample size125
 Total time s63.8±26.187.3±40.60.169
 Number of swallows7.0 (5.5–10.0)10.0 (7.0–14.0)0.134
 Number of bites3.1±1.25.4 ±1.10.002*
 Number of chews65.7±18.775.2±31.50.445
 Chews per bite22.3 (16.1–25.3)14.6 (10.0–15.8)0.011*
 Swallows per bite1.2±0.60.9±0.90.330
 Time per bite s19.0 (18.0–27.4)13.4 (11.5–16.3)0.058
 Time per chew s1.0±0.31.2±0.40.225
 Time per swallow s18.4 (15.4–24.7)14.2 (13.6–20.1)0.598
 Sample size125
 Tongue strength kPa42.6±16.150.2 ±15.60.805
 Sample size125
 Self-assessed dysphagia score1.0 (0.5–2.0)6.0 (3.0–10.0)0.085
IR scalenes
 Sample size94
 IR onset ms56.2±9.760.9±11.20.461
 IR duration ms62.3±28.675.2±32.60.485
 IR area mV·ms14.5 (10.0–17.7)15.3 (13.3–32.3)0.643
 IR peak %62.1 (60.4–70.1)60.2 (47.3–66.7)0.643
 IR peak time ms82.0 (76.0–94.5)93.5 (89.3–108)0.142
IR diaphragm
 Sample size63
 IR onset ms58.0±7.986.0±14.10.007*
 IR duration ms71.2±24.563.7±34.90.715
 IR area mV·ms19.3±8.921±18.20.854
 IR peak %62.4 (53.6–64.7)61.4 (36.8–78.8)0.796
 IR peak time ms101 (95.0–110)104 (104–115)0.294

Data are presented as n, median (interquartile range) or mean±sd, unless otherwise stated. Within-group analysis of participants with COPD who had clinical signs of airway invasion (events) during timed water swallow test (TWST) test for swallowing liquids. The presence of an inhibitory reflex (IR) in the scalene and diaphragm muscles was assessed using 2sd criteria, i.e. airway occlusion evoked a decrease in inspiratory muscle electromyographic activity (EMG) of 2sd below pre-occlusion EMG levels, which lasted ≥10 ms [12]. TOMASS: test of mastication and swallowing solids; IOPI: Iowa Oral Performance Instrument; EAT-10: eating assessment tool. *: p<0.05 for t-test comparisons and Spearman's correlations within the COPD group.