Monitoring military pilots with textile sensors: physiological responses and signal quality under extreme conditions

Figures

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  Figure 1. Simulated altitude profile. The blue periods highlight the phases when the participants had their aviator oxygen masks removed (phases 3 and 5). Details regarding the phases are available in Table 2. The orange annotations (i1 to i6) indicate the specific 30-second measurement intervals for ECG and breathing signals.

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  Figure 2. G-force exposure protocol for the qualification profile. The intervals i1 to i9 were used for the numeric analysis of the wearable system data (ECG and breathing signals). The yellow annotations (i1 to i9) indicate the specific 30-second measurement intervals for ECG and breathing signals with exception for i2, i5 and i8 in orange representing the 15-second high-G exposure intervals.

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  Figure 3. Heart rate and heart rate variability for various measurement intervals (i1 – i9; further information on the prevailing conditions during the individual measurement intervals can be found in Figure 1) during hypobaric hypoxia exposure (*p ≤ 0.05, **p≤ 0.01). (A) Median HR across n = 10 participants for each interval (Hypoxic conditions highlighted in blue), with marked significance for consecutive changes in mean HR. (B) Overview of participant-based mean HR for each interval. (C) Median SDNN across n=8 for each interval (Hypoxic conditions highlighted in blue), with marked significance for consecutive changes in mean SDNN. (D) Overview of participant-based mean SDNN for each interval.

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  Figure 4. Respiratory frequency and respiratory sensor elongation amplitude for various measurement intervals (i1 – i9; further information on the prevailing conditions during the individual measurement intervals can be found in Figure 1) during hypobaric hypoxia exposure (Hypoxic conditions highlighted in blue). (A1) Shows the median for the respiratory amplitude across all intervals for n=6. (A2) Shows the median for the respiratory frequency across all intervals for n=6. (B1) Heatmap for interpersonal variability of respiratory amplitude for each interval (n=6). (B2) Heatmap for interpersonal variability of respiratory frequency for each interval (n=6).

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  Figure 5. Heart rate and heart rate variability for various measurement intervals (i1 – i9; further information on the prevailing conditions during the individual measurement intervals can be found in section 2.3, Figure 2) during high G-exposures (*p ≤ 0.05, **p≤ 0.01, ***p ≤ 0.001). (A) Median HR across n=9 for pre and post high G-exposure intervals, with marked significance for consecutive changes in mean HR. (B) Overview of participant-based mean HR for each interval. (C) Overview of changes in HR from i1 to post-G-Exposure, with mean significance level. (D) Mean SDNN across n=8 participants for pre and post high G-exposure intervals.

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  Figure 6. Respiratory frequency and respiratory sensor elongation amplitude for various measurement intervals (i1 – i9; further information on the prevailing conditions during the individual measurement intervals can be found in Figure 2) during high G-exposures. (A1) Shows the median for the respiratory amplitude across all intervals for n=9. (A2) Shows the median for the respiratory frequency across all intervals for n=9. (B1) Heatmap for interpersonal variability of respiratory amplitude for each interval (n=9). (B2) Heatmap for interpersonal variability of respiratory frequency for each interval (n=9).