Concave Pattern of a Maximal Expiratory Flow-Volume Curve: A Sign of Airflow Limitation in Adult Bronchial Asthma

Table 2

Correlation between % changes of angle β, SF_25%, and SF_50% and % changes of spirometric parameters after SABA inhalation.

	Angle β versus		SF25% versus		SF50% versus
	𝑟	𝑃	𝑟	𝑃	𝑟	𝑃
FVC (% change)	0.0043	0.98	−0.085	0.57	−0.32	0.11
FEV1 (% change)	0.32	0.1	−0.23	0.24	−0.32	0.1
PEF (% change)	−0.15	0.47	0.096	0.63	0.0067	0.97
FEF25-75% (% change)	0.57	0.0017	−0.43	0.024	−0.31	0.12
FEF25% (% change)	0.075	0.71	−0.12	0.54	−0.35	0.074
FEF50% (% change)	0.71	<0.0001	−0.35	0.078	−0.25	0.21
FEF75% (% change)	0.47	0.013	−0.53	0.0046	−0.54	0.0041
SF50% (% change)	0.12	0.54	−0.9	<0.0001	—	—
SF25% (% change)	0.33	0.089	—	—	—	—
Angle 𝛽 (% change)	—	—	—	—	—	—

Bold text indicates significant correlation between the parameters.