Table 2.

Pulmonary function tests and arterial blood gases of COPD patients

Variable	Stage I (n = 10)	Stage II (n = 17)	Stage III (n = 17)	Stage IV (n = 20)
Pulmonary function tests
FEV1, liters/s	2.83±0.22	1.9±0.45	0.98±0.29	0.72±0.13
p1		<0.001*	<0.001*	<0.001*
p2			<0.001*	<0.001*
p3				0.009*
FEV1, %	81.7±2.31	64.41±6.21	37.12±5.78	25.45±4.21
p1		<0.001*	<0.001*	<0.001*
p2			<0.001*	<0.001*
p3				<0.001*
FVC, liters/s	4.80±0.58	3.23±0.78	2.17±0.63	1.78±0.43
p1		<0.001*	<0.001*	<0.001*
p2			<0.001*	<0.001*
p3				0.058
FVC, %	113.8±12.66	87.06±12.23	63.47±15.22	50.3±9.85
p1		<0.001*	<0.001*	<0.001*
p2			<0.001*	<0.001*
p3				0.002*
FEV1/FVC%	59.42±6.08	59.71±9.04	45.44±4.68	41.2±6.68
p1		0.917	<0.001*	<0.001*
p2			<0.001*	<0.001*
p3				0.066
FEF25–75, liters/s	1.95±0.52	1.14±0.51	0.42±0.14	0.29±0.05
p1		<0.001*	<0.001*	<0.001
p2			<0.001*	<0.001
p3				0.264
FEF25–75, %	48.6±11.35	33±10.64	13.59±3.43	8.9±1.48
p1		<0.001*	<0.001*	0.000*
p2			<0.001*	0.000*
p3				0.056
Arterial blood gases
paO2, mm Hg	92.4±6.36	89.65±6.26	76.94±7.76	60.95±12.67
p1		0.452	<0.001*	<0.001*
p2			<0.001*	<0.001*
p3				<0.001*
paCO2, mm Hg	30.04±4.8	34.84±4.08	42.62±5.98	52.14±15.22
p1		0.211	0.002*	<0.001*
p2			0.020*	<0.001*
p3				0.004*
pH	7.44±0.03	7.42±0.04	7.41±0.07	7.42±0.05
p1		0.315	0.168	0.452
p2			0.658	0.739
p3				0.429
HCO3, mmol/l	21.09±4.08	24.17±3.66	29.15±4.26	35.15±7.05
p1		0.140	<0.001*	<0.001*
p2			0.007*	<0.001*
p3				0.001*
O2 Sat, %	97.54±0.71	95.57±5.85	95.42±3.59	88.32± 7.47
p1		0.373	0.337	<0.001*
p2			0.936	<0.001*
p3				<0.001*

FEV₁ = Forced expiratory volume in 1 s; FVC = forced vital capacity; FEF = forced expiratory flow; PaO₂ = arterial partial pressure of oxygen; PaCO₂ = arterial partial pressure of carbon dioxide; HCO₃ = bicarbonate; O₂ Sat = O₂ saturation; p1 = versus stage I; p2 = versus stage II; p3 = versus stage III. Data expressed as mean ± SD; p values with an asterisk are significant.