Table 3.

Airway dimensions

Measurement	Healthy Controls (n = 9)	Asthma (n = 19)	Between Groups t-Test (P Value)
Baseline
Baseline diameter FRC	5.19 ± 0.64	5.06 ± 1.0	0.74
Baseline diameter TLC	5.91 ± 0.83	5.68 ± 1.3	0.63
Wall thickness (fraction of diameter) FRC	0.24 ± 0.04	0.31 ± 0.06	0.006*
Wall thickness (fraction of diameter) TLC	0.19 ± 0.03	0.25 ± 0.07	0.03*
% Δ diameter from FRC to TLC baseline	16 ± 8%	14 ± 11%	0.62
After maximum relaxation
Relaxed diameter FRC	6.4 ± 0.8	6.2 ± 1.0	0.53
Relaxed diameter TLC	6.6 ± 0.9	6.6 ± 1.1	0.91
% Δ diameter at FRC (baseline to relaxed)	27 ± 7% (P < 0.0001)*	27 ± 16% (P < 0.0001)*	0.62†
% Δ diameter at TLC (baseline to relaxed) (defined as airway tone)	13 ± 3% (P < 0.0001)*	22 ± 17% (P < 0.0001)*	0.83†
Wall thickness (fraction of diameter) FRC after relaxation	0.18 ± 0.03	0.22 ± 0.03	0.002*
Wall thickness (fraction of diameter) TLC after relaxation	0.16 ± 0.02	0.19 ± 0.03	0.03*
% Δ wall thickness (fraction of diameter) FRC (baseline to relaxed)	24.4 ± 4.8 (P < 0.0001)*	24.9 ± 14 (P < 0.0001)*	0.11
% Δ wall thickness (fraction of diameter) TLC (baseline to relaxed)	14.4 ± 3.6 (P < 0.0001)*	21.8 ± 13 (P < 0.0001)*	0.92
% Δ diameter from FRC to TLC relaxed	3 ± 4%	10 ± 9%	0.046*

Values are means ± SD. P values within groups represent paired comparisons of baseline vs. postalbuterol maximum relaxation measurements.

^*P < 0.05.

^†Analysis by mixed within-between groups ANOVA.