. 2021 Mar 2;160(1):175–186. doi: 10.1016/j.chest.2021.02.047

Table 2.

Impact of Circuit Setup on Ventilator Performance During Noninvasive Ventilation and CPAP

Variables	Setup 1	Setup 2	Setup 3	Setup 4	Setup 5	Setup 6	Setup 7	Setup 8	Setup 9
Variables	[Median (IQR)]	[Median (IQR)]	[Median (IQR)]	[Median (IQR)]	[Median (IQR)]	[Median (IQR)]	[Median (IQR)]	[Median (IQR)]	[Median (IQR)]
Noninvasive ventilation
Flow to trigger, L/min	23.5 [6.5 to 24.7]^a	24.1 [7.9 to 25.3]^a	23.2 [7.2 to 24.3]^a	24.3 [7.2 to 25.2]^a	–11.3 [–15.4 to 7.4]	10.4 [3.7 to 20]^a	14.1 [4.1 to 19]^a	21.6 [20.1 to 24.7]^a	NA
Inspiratory effort, cm H₂O	–7.8 [–10.3 to –5.9]^a	–7.7 [–10.3 to –5.8]^a	–7.4 [–10.3 to –6.0]^a	–7.6 [–10.4 to –6.0]^a	–3.9 [–4.4 to –3.5]	–7.3 [–9.7 to –6.0]^a	–7.0 [–8.8 to –5.57]^a	–10.5 [–11.2 to –9.9]^a	NA
Time to trigger, ms	165 [102 to 312]^a	163 [99 to 310]^a	153 [104 to 307]^a	158 [104 to 320]^a	51 [41 to 61]	149 [105 to 266]^a	135 [92 to 211]^a	323 [278 to 402]^a	NA
Delivered pressure, cm H₂O	15.6 [14.6 to 15.7]	15.9 [15 to 16]	13.5 [13.1 to 13.9]^a	13.9 [13.6 to 14.4]^a	15.6 [15 to 15.9]	16.2 [16.1 to 17.5]^a	16.5 [16.4 to 16.5]^a	16.3 [15.5 to 16.6]^a	NA
Work of breathing, mJ	823 [717 to 1,270]	809 [709 to 1,281]	783 [675 to 1,320]	780 [686 to 1,240]	861 [747 to 1,373]	872 [815 to 1,046]	520 [301 to 1,129]^a	875 [766 to 1,406]	NA
Tidal volume, mL	563 [280 to 748]	573 [285 to 780]	535 [267 to 715]^a	544 [270 to 732]	553 [325 to 776]	563 [277 to 770]	592 [331 to 949]	529 [512 to 620]	NA
Patient-ventilator asynchrony, No. (%)	2 (2%)	6 (7%)	2 (2%)	2 (2%)	2 (2%)	37 (41%)	11 (12%)	38 (42%)	NA
PTP_t, cm H₂O × s	0.255 [0.140 to 0.300]^a	0.270 [0.130 to 0.300]^a	0.260 [0.140 to 0.290]^a	0.260 [0.140 to 0.298]^a	0.050 [0.040 to 0.060]	0.260 [0.165 to 0.350]^a	0.170 [0.150 to 0.290]^a	0.640 [0.470 to 1.255]^a	NA
CPAP
Flow to trigger, L/min	33.0 [14.3 to 36.6]	33.6 [13.7 to 37.9]	33.2 [14.6 to 37]	33.7 [13.7 to 38]	34.6 [7 to 38.3]	23.2 [8.9 to 25.6]^a	23.3 [7.8 to 25.1]^a	29.1 [12.2 to 35.1]	NA
Time to trigger, ms	289.1 [210.9 to 354]	291 [207 to 356]	311.5 [226.1 to 401.4]^a	301.8 [214.4 to 379.9]	293.9 [220.2 to 314.5]	194.3 [160.2 to 279.8]^a	177.7 [146.5 to 276.4]^a	363.3 [265.6 to 404.8]^a	NA
Delivered pressure, cm H₂O	7.8 [7.8 to 7.9]^a	7.9 [7.9 to 7.9]^a	6.8 [6.6 to 6.9]^a	7.0 [6.9 to 7.1]^a	8.0 [7.9 to 8.1]	7.8 [7.4 to 7.9]^a	7.9 [7.8 to 8.2]^a	7.9 [7.9 to 8]^a	6.5 [6.5 to 6.6]^a
Tidal volume, mL	344 [181 to 474]	345 [182 to 485]^a	339 [178 to 461]	340 [180 to 470]	337 [173 to 461]	352 [183 to 526]^a	360 [183 to 599]^a	339 [182 to 455]	320 [173 to 414]
PTP_t, cm H₂O × s	0.353 [0.321 to 0.599]	0.325 [0.297 to 0.552]^a	0.478 [0.376 to 0.643]	0.365 [0.325 to 0.59]	0.405 [0.343 to 0.68]	0.312 [0.257 to 0.364]^a	0.293 [0.219 to 0.314]^a	0.380 [0.322 to 0.863]	0.860 [0.526 to 1.039]^a

Values represent median (IQR) unless otherwise indicated. IQR = interquartile range; NA = not applicable; PTP_t = inspiratory pressure-time product.

P < .05 after correction for multiple comparisons when compared with setup 5.