Figures
- FIGURE 1
Flow diagram of overall study design, including each section, devices used and participants. MBW: multiple-breath washout; CF: cystic fibrosis; HC: healthy control; RMS: respiratory mass spectrometer.
- FIGURE 2
Flowmeters of the Exhalyzer D (nitrogen; black box) and Innocor (sulfur hexafluoride; white box) were attached in series with airtight plastic tubing. After calibrating each device with this set-up, the gas concentration and breath number during a multiple-breath washout test were then measured simultaneously. In some cases, a respiratory mass spectrometer (RMS) gas probe was also placed between the other devices (grey dot) to read gas concentrations directly using the RMS.
- FIGURE 3
Bland–Altman plot of the difference in lung clearance index taken from the traditional end-point of 1/40th of the starting concentration (LCI2.5) between Exhalyzer D (nitrogen (N2ExD)) and Innocor (sulfur hexafluoride (SF6Inn)) in a) participants with cystic fibrosis (CF) and b) healthy control (HC) participants. The solid line is the mean difference between devices (4.5 in CF and 0.92 in HC) and the dotted lines represent the limits of agreement (0.08–8.92 in CF and −0.38–2.22 in HC). The difference between devices becomes disproportionately larger with a higher (worse) LCI.
- FIGURE 4
Bland–Altman plots of the difference in lung clearance index (LCI) taken from the 1/20th end-point of the starting concentration (LCI5) between Exhalyzer D (nitrogen (N2ExD)) ExD) and Innocor (sulfur hexafluoride (SF6Inn)) in a) participants with cystic fibrosis (CF) and b) healthy control (HC) participants. The solid line is the mean difference between devices (1.0 in CF and 0.01 in HC) and the dotted lines represent the limits of agreement (−0.48–2.49 in CF and −0.59–0.62 in HC). The difference between devices becomes disproportionately larger with a higher (worse) LCI. The difference in LCI5 is not as large as the difference in LCI2.5.
- FIGURE 5
Graph of an individual cystic fibrosis patient's gas concentration decline throughout a simultaneous washout of sulphur hexafluoride and nitrogen versus breath number. The gases are displayed in a normalised log scale for ease of visualisation. The vertical lines (dashed: SF6; solid: N2) represent the end-tidal gas concentration at 1/40th of the starting concentration; beyond this point is the extended washout period.
Tables
- TABLE 1
Comparison of multiple-breath washout devices, cystic fibrosis (CF) and healthy control (HC) demographics and lung clearance index (LCI) results
CF (n=47) HC (n=42) Female 24 (51%) 26 (62%) Age years 16.05 (5.9–63.7) 24.32 (5.7–56.1) Height cm, Z-score 154.6±52.2, −0.07±1.1 158.4±17.9, −0.79±1.1 Weight kg, Z-score 52.2±18, 0.60±1.1 59.7±20.6, −0.27±1.2 FEV1 % pred, Z-score 72.9±16.8, −2.29±1.43 Not done SF6Inn N2ExD Difference p-value SF6Inn N2ExD Difference p-value LCI2.5 9.5±2.3 (8.82 to 10.19) 14.0±3.7 (12.88 to 15.14) −4.5 (−5.2 to −3.8), p=<0.0001 6.3±0.5 (6.12–6.5) 7.3±0.72 (7.03–7.48) −0.9 (−1.1 to −0.7), p<0.0001 LCI5 6.8±1.4 (6.38 to 7.23) 7.9±1.7 (7.31 to 8.32) −1.01 (−1.2 to −0.8), p<0.0001 5.1±0.4 (4.97 to 5.20) 5.1±0.3 (5.01 to 5.20) −0.02 (−0.12 to 0.08), p=0.709 FRC2.5 L 1.9±0.6 (1.73 to 2.09) 2.5±0.9 (2.23 to 2.78) −0.6 (−0.7 to −0.5), p<0.0001 2.3±0.8 (2.05–2.55) 2.5±0.9 (2.25–2.84) −0.2 (−0.3 to −0.2), p<0.0001 CEV L 18.4±7.7 (16.1–20.8) 38.5±18.7 (33.9–44.2) −20.1 (−23.9 to −16.3), p<0.0001 14.5±5.6 (12.8–16.2) 19.8±7.9 (17.4–22.3) −5.3 (−6.4 to −4.2), p<0.0001 SF6Inn Mean LCI difference 3.2±0.4 (2.5 to 3.9) p<0.0001 N2ExD Mean LCI difference 6.8±0.6 (3.6 to 7.9) p<0.0001 Results show mean±sd or median (range) with 95% confidence intervals for LCI2.6 and functional residual capacity (FRC). FEV1: forced expiratory volume in 1 s; HC: healthy control; LCI: lung clearance index; LCI2.5: lung clearance index calculated from washout to 1/40th of the tracer gas starting concentration; LCI5: lung clearance index calculated from washout to 1/20th of the tracer gas starting concentration; FRC: Functional Residual Capacity; CEV: Cumulative Expiratory Volume; MBW: multiple-breath washout; N2ExD: Exhalyzer D nitrogen device; SF6Inn: modified Innocor sulfur hexafluoride device.
Supplementary Material
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Supplementary material 00234-2018.supplement
