TABLE 3.

Mean MVV values measured directly and predicted MVV values.

	Healthy			COPD
	All	Male	Female	All	GOLD II	GOLD III	GOLD IV
Subjects(n)	207	102	105	83	29	30	24
MVV(L/min)	126.4 ± 36.6	149.4 ± 33.3	104.3 ± 23.6	46.5 ± 18.2	63.9 ± 13.6	45.0 ± 10.7	27.3 ± 6.7
Equation 1(L/min)	95.2 ± 23.9**	110.0 ± 20.2**	81.1 ± 17.9**	35.2 ± 13.0**	49.1 ± 8.4**	33.5 ± 5.6**	20.8 ± 4.2**
Equation 2(L/min)	111.1 ± 27.9**	128.3 ± 23.6**	94.6 ± 20.8**	41.1 ± 15.2**	57.2 ± 9.8*	39.1 ± 6.5*	24.2 ± 4.9*
Equation 3(L/min)	119.1 ± 29.9**	137.4 ± 25.3**	101.4 ± 22.3*	44.1 ± 16.3	61.3 ± 10.5	41.9 ± 6.9	26.0 ± 5.2
Equation 4(L/min)	127.0 ± 31.8	146.6 ± 27.0	108.2 ± 23.8*	47.0 ± 17.4	65.4 ± 11.2	44.6 ± 7.4	27.7 ± 5.6
Equation 5(L/min)	130.1 ± 32.7*	150.3 ± 27.6	110.9 ± 24.4**	48.2 ± 17.8	67.0 ± 11.5	45.8 ± 7.6	28.4 ± 5.7

Results of direct maximal voluntary ventilation (MVV) measured and estimated by predicted equations. Student’s t-test for paired samples with a significance level of P < 0.05 were performed for the comparisons between measured MVV and estimated MVV. *Significantly difference (p < 0.05) when the direct values were compared with the predictive values **Significantly difference (p < 0.0001) when the direct values were compared with the predictive values. The results expressed in bold letters correspond to the equations that did not show significant differences with the direct value of MVV. Data are presented are liter per minute (L/min).