Investigating the effects of strap tension during non-invasive ventilation mask application: a combined biomechanical and biomarker approach

Figures & data

Figure 1 (A) The location of the Sebutape on the bridge of the nose pre- and post-mask applications. (B) Graduated marks (white vertical lines) placed on the straps of the mask to incrementally increase the strap tension. (C) Location of Talley pressure monitoring cells on the nose and cheeks.

Table 1 Summary of outcome measure data from M1 and M2 across three strap tensions

Outcome measure	M1			M2
	T1	T2	T3	T1	T2	T3
Interface pressure – nose (mmHg), mean ± SD	84 ± 39	132 ± 63	158 ± 54	94 ± 49	102 ± 52	121 ± 55
Interface pressure – right cheek (mmHg), mean ± SD	32 ± 18	42 ± 21	54 ± 24	39 ± 12	41 ± 21	36 ± 20
Interface pressure – left cheek (mmHg), mean ± SD	37 ± 17	30 ± 13	42 ± 24	32 ± 21	38 ± 26	33 ± 29
Temperature (°C), median (range)	34 (32–35)	34 (33–36)	34 (32–36)	33 (29–35)	34 (32–35)	34 (32–35)
Humidity (% RH), median (range)	83 (67–91)	84 (75–92)	84 (77–92)	84 (77–96)	80 (67–93)	84 (73–94)
Discomfort score (VAS/10),* median (range)	4 (0–7)	5 (0–7)	6 (0–7)	4 (0–7)	5 (0–7)	5 (1–8)

Note:

* 1 = very comfortable, 10 = very uncomfortable.

Abbreviations: M1, mask 1; M2, mask 2; T1, tension 1; T2, tension 2; T3, tension 3; RH, relative humidity; VAS, visual analog scale.

Figure 2 Box and whisper plots of the IL-1α cytokine ratios from pre- to post-mask application. Note: ^*P-value =0.04.

Abbreviations: M1, mask 1; M2, mask 2.

Figure 3 (A) IL-8 cytokine concentrations for participant P2 during M1 application. (B) IL-1α cytokine concentrations for participant P12 during M2 application. (C) IL-2 cytokine concentrations for participant P4 during M1 application.

Abbreviations: M1, mask 1; M2, mask 2; T1, tension 1; T2, tension 2; T3, tension 3; BL, baseline.

Table 2 Summary of ratio changes in the cytokines pre- to post-mask application

Pre- to post-mask ratio	M1			M2
	T1	T2	T3	T1	T2	T3
IL-1β, median (range)	0.75 (0.62–2.14)	1.18 (0.56–2.44)	1.27 (0.50–2.14)	0.73 (0.34–1.88)	1.44 (0.74–3.08)	0.70 (0.63–1.30)
IL-8, median (range)	1.34 (0.39–3.20)	1.45 (0.18–2.75)	1.60 (0.43–5.28)	0.53 (0.26–2.17)	2.84 (0.27–7.11)	0.62 (0.34–1.46)
IL-2, median (range)	2.60 (0.56–6.13)	0.90 (0.11–2.60)	0.53 (0.19–9.49)	0.34 (0.18–1.77)	2.00 (0.24–21.18)	0.50 (0.31–4.26)
IL-6, median (range)	1.44 (0.20–2.05)	0.71 (0.21–2.55)	1.01 (0.55–6.10)	0.90 (0.45–2.36)	1.30 (0.62–2.99)	0.80 (0.58–2.35)
IL-10, median (range)	2.24 (0.41–4.60)	1.03 (0.14–2.18)	0.73 (0.15–9.14)	0.37 (0.26–1.95)	2.49 (0.26–23.50)	0.66 (0.34–3.45)
IFN-γ, median (range)	2.01 (0.38–3.16)	0.87 (0.19–1.77)	0.66 (0.26–5.85)	1.32 (0.29–2.05)	1.17 (0.35–10.00)	0.62 (0.39–2.40)

Abbreviations: M1, mask 1; M2, mask 2; T1, tension 1; T2, tension 2; T3, tension 3.

Figure 4 Relationship between cytokine groups: (A) IL-1 family, IL-1α and IL-1β; (B) IL type II family, IFN-γ and IL-10 and (C) γ family, IL-2 and IFN-γ.