Table 2. Normative BFI waveform morphology at rest and during hypercapnia. Median (interquartile range) values for morphological features of the BFI waveform at rest (room air inhalation) and during hypercapnia, along with the percent change in each parameter from rest to hypercapnia. Bold p-values denote significance assessed at the 0.05 level with a two-sided Wilcoxon signed-rank test between rest and hypercapnic values. (Abbreviations: EDF = end diastolic flow, MF = mean flow, PSF = peak systolic flow, AMP = pulse amplitude, AUC = pulse area under the curve, PI = pulsatility index, RI = resistivity index).
| Comparison between resting and hypercapnia (n = 30) |
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|---|---|---|---|---|
| Parameter | Resting state | Hypercapnia | p-value | % Change |
| EDF (1e-9 cm2/s) | 5.61 (4.40, 10.13) | 7.79 (6.03, 12.36) | < 0.001 | 29.61 (16.37, 57.84) |
| MF (1e-9 cm2/s) | 8.57 (6.45, 13.67) | 12.45 (8.01, 18.00) | < 0.001 | 31.01 (18.64, 53.32) |
| PSF (1e-9 cm2/s) | 14.73 (12.18, 22.72) | 19.51 (15.06, 29.12) | < 0.001 | 24.29 (9.75, 40.77) |
| AMP (1e-9 cm2/s) | 9.44 (7.80, 14.12) | 10.91 (8.98, 15.24) | 0.001 | 18.25 (3.31, 33.76) |
| AUC (1e-9 cm2/s) | 3.44 (2.08, 4.12) | 4.30 (2.81, 5.89) | < 0.001 | 31.84 (14.22, 47.71) |
| PI (unitless) | 1.07 (0.83, 1.31) | 0.87 (0.78, 1.32) | 0.014 | -9.08 (-23.96, 3.02) |
| RI (unitless) | 0.59 (0.51, 0.66) | 0.54 (0.49, 0.67) | 0.054 | -4.53 (-16.71, 3.91) |