Methods: Cross-sectional, prospective study in 150 adolescents from 11 to 17 years old, grouped according to their body mass index (BMI): group 1 (G1) healthy eutrophic (BMI percentile 10 - 84 of the boards of the CDC) Group 2 (G2) not morbidly obese (BMI 85-98) and group 3 (G3), morbidly obese (BMI> 99). Anthropometry was performed and plethysmography. Statistics: mean, standard deviation (SD), confidence interval 95% (CI95%). ANOVA post hoc analysis.
Results: The mean age was 13.7 years, 46.7% women and 53.3% men. G1 had 40 children, G2 had 67 and G3 had 43. Mean values and CI95% of vital capacity (VC) of G1 was 104.97% (100.12 - 109.82), G2 114.65% (111.36 - 117.94), G3 118.09% (112.71 - 123.47) [G1 with significant difference compared the G2 and G3 p <0.05]. The total lung capacity (TLC) was 124.67% G1 (105.94 - 143.40), G2 145.61% (114.77 - 176.45), G3 132.27% (125.14 - 139.41) [no intergroup difference]. Functional residual capacity (FRC) of G1 was 145.95% (133.75 - 158.14), G2 122.41% (110.23 - 134.59), G3 115.74% (103.05 - 128.43) [G1 with significant difference compared with the G2 and G3 p <0.05]. The expiratory reserve volume (ERV) of G1 was 113.15% (90.57 - 135.72), G2 68.64% (60.34 - 76.93), G3 67.33% (52.40 - 82.26) [In contrast to the G1 compared to G2 and G3 p <0.05]. Inspiratory capacity (IC) in G1 was 76.90% (66.94 - 86.85), G2 102.04% (94.94 - 109 145), G3 115.72% (105.61 - 125.82) [G1 with significant difference compared with the G2 and G3 p < 0.05].
Conclusions: The morbidly obese have a lower FRC and ERV and increased IC and CV.