Table 3.
Respiratory profile parameters for the eight different conditions tested
| Parameter (median [IQR]) | Spontaneous breathing (SB) | Assisted breathing without resistance | Assisted breathing with resistance | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Without resistance | With resistance | p values | PS low | PS high | NAVA | p values | PS low | PS high | NAVA | p values | |
| MV (L/min) | 9.9 (8.7–14.4) | 8.9 (7.1–10.5) | p = 0.03 | 13.7 (10.6–18.5) | 16.4 (10.7–24.4) | 12.9 (11.1–18.5) |
*p = 0.001, p < 0.05 for all the ventilation modalities compared to SB without resistance p > 0.05 for all pairwise comparisons between PS low, PS high and NAVA |
11.1 (10.5–12.1) | 13.7 (10.9–18.0) | 11.1 (9.9–12.5) |
#p = 0.001 p < 0.05 for all the ventilation modalities compared to SB with resistance p < 0.05 between PS high and PS low and between PS high and NAVA |
| RR (br/min) | 14.6 (12.5–15.7) | 10.9 (8.7–12.0) | p < 0.001 | 15.5 (12.9–17.7) | 15.3 (13.7–16.5) | 14.0 (12.1–17.8) | *p = 0.22 | 12.7 (10.2–13.6) | 12.5 (10.6–13.8) | 12.1 (10.4–16.5) | #p = 0.053 |
| VT (L) | 0.81 (0.65–1.00) | 0.90 (0.70–1.05) | p = 0.54 | 0.99 (0.79–1.20) | 0.99 (0.69–1.71) | 0.92 (0.74–1.21) |
*p = 0.004 p < 0.05 for all the ventilation modalities compared to SB without resistance. p > 0.05 for all pairwise comparisons between PS low, PS high and NAVA |
0.88 (0.86–1.01) | 1.33 (0.96–1.48) | 0.90 (0.78–1.04) | #p = 0.055 |
| Tin (ms) | 1.76 (1.48–2.00) | 2.41 (1.91–2.67) | p < 0.001 | 1.54 (1.38–1.78) | 1.45 (1.36–1.73) | 1.68 (1.29–1.91) | *p = 0.46 | 1.78 (1.63–2.01) | 1.78 (1.62–1.96) | 1.91 (1.43–2.15) |
#p = 0.027. p < 0.05 between SB with resistance and PS low, SB with resistance and PS high and SB with resistance and NAVA |
| Tiex (ms) | 0.17 (0.10–0.22) | 0.27 (0.22–0.38) | p < 0.001 | 0.20 (0.14–0.25) | 0.24 (0.11–0.29) | 0.24 (0.21–0.31) | *p = 0.23 | 0.31 (0.21–0.33) | 0.41 (0.31–0.64) | 0.28 (0.20–0.40) |
#p = 0.039. p < 0.05 between SB with resistance and PS high, and between PS low and PS high |
| Ti/Ttot | 0.41 (0.40–0.45) | 0.44 (0.42–0.47) | p = 0.10 | 0.41 (0.39–0.44) | 0.42 (0.37–0.45) | 0.44 (0.41–0.47) | *p = 0.17 | 0.43 (0.40–0.44) | 0.41 (0.39–0.45) | 0.44 (0.39–0.45) | #p = 0.97 |
For the multiple comparisons (Friedman analyses), only the subjects for whom all the conditions compared could be recorded were considered. The corresponding median values summarize these patients only
MV minute ventilation, RR respiratory rate, VT tidal volume, Tin neural inspiratory time, Tiex inspiratory time in excess, PS Pressure support, NAVA neurally adjusted ventilatory assist
* Comparison between spontaneous non-assisted breathing without resistance and assisted breathing without resistance under PS low, PS high and NAVA
#Comparison between spontaneous non-assisted breathing with resistance and assisted breathing with resistance under PS low, PS high and NAVA