[Repeatability of spirometry's expiratory flows]

The quality of the spirometry is estimated with criteria of acceptability and repeatability. The repeatability criteria accepted by consensus is < 0.150 L.

To know the repeatability in quality A spirometry.

Analytical cross-sectional design. The demographic variables and the 3 best spirometry curves with normal, suggestive of restriction and bronchial obstruction profiles were obtained from consecutive subjects of both genders from 18 to 80 years of age. The repeatability was analyzed with the mean difference (bias) and the intraclass correlation coefficient.

630 curves from 210 subjects were accepted. Group age 60 ± 15 years. Female predominance 113 (53.8%), occupation: domestic services 61 (29%), and diagnosed with chronic obstructive pulmonary disease: 70 (33.4%). The differences in the curves were < 0.150 L. The mean difference (bias) and the intraclass correlation coefficient (95% confidence interval, 95% CI) of the forced expiratory volume in the first second were 1 vs. 2 maneuver: -0.01 (0.13, -0.14), 0.997 (95% CI 0.996, 0.998); 2 vs. 3 maneuver: 0.00 (0.13, -0.13), 0.997 (95% CI 0.996, 0.998), and maneuver 1 vs. 3: -0.00 (0.16, -0.17), 0.995 (95% CI 0.994, 0.996). Forced vital capacity: 1 vs. 2 maneuver: -0.01 (0.17, -0.18), 0.996 (95% CI 0.995, 0.997); 2 vs. 3 maneuver: 0.01 (0.17, -0.16), 0.997 (95% CI 0.0.996, 0.998), and maneuver 1 vs. 3: -0.00 (0.18, -0.19), 0.996 (95% CI 0.995, 0.997).

The repeatability obtained in spirometry with quality A validates the use of the repeatability criterion of 0.150 L.