Presence of variable extrathoracic airflow limitation in patients with a negative methacholine challenge test

Table 2 Methacholine challenge test data

	Patient cohort (N = 13)
Baseline PFT
FVC, L	3.97 ± 0.98
FVC % predicted	98 ± 12.32
FEV₁, L	3.03 ± 0.80
FEV₁% predicted	92.55 ± 12.01
FEV₁/FVC	0.76 ± 0.08
D_LCO, mL/min/mmHg	23.67 ± 6.14
D_LCO, % predicted	83.02 ± 17.89
FEF₅₀/FIF₅₀, %	72 ± 21
^aPFT after methacholine challenge test
FVC, L	3.89 ± 0.92
FVC % predicted	96.6 ± 12.32
FEV₁, L	3.16 ± 0.83
FEV₁% predicted	99.7 ± 14.31
FEV₁/FVC	0.81 ± 0.06
FEF₅₀/FIF₅₀	1.21 ± 0.13
Increase in FEF₅₀/FIF₅₀ from baseline	0.4 ± 0.14
Fall in FIF₅₀ > 20% from baseline, n (%)	11 (84)
Methacholine concentration^a, mg/mL, median (range)	1.0 (0.25–16)

Data are means ± standard deviation
PFT: pulmonary function tests; FVC: forced vital capacity; FEV₁: forced expiratory volume in one second; FEF₅₀: forced expiratory flow rate at 50% vital capacity; FIF₅₀: forced inspiratory flow rate at 50% vital capacity; D_LCO: diffusion capacity of the lungs for carbon monoxide
^aThe first methacholine concentration at which FEF₅₀/FIF₅₀ was either > 100% or further increased if baseline FEF₅₀/FIF₅₀ after nebulized saline (vehicle) already exceeded 100%

ISSN: 1710-1492