These results are similar to those observed by Dávila-Cervantes SCR7 et al. (2004) that found a decrease in VT 1 year after surgery ( Dávila-Cervantes et al., 2004). The VE in the group of obese patients was higher preoperatively than in the control

group. These results are similar to those of Chlif et al. (2009) and Cavallazzi et al. (1981), who found the VE of obese individuals was above the normal limit. The higher VE in the preoperative patients can be attributed to the adverse effects of obesity on pulmonary function, which is directly related to the presence of fat in the rib cage and to the blood redistribution to the thoracic compartment from compression of the abdominal viscera, which causes a reduction in thoracic compliance ( Harik-Khan et al., 2001). The overload imposed by the adipose tissue on the rib cage can increase the effort needed Pexidartinib research buy to breathe and the energy needed to expand the lungs of obese individuals ( Naimark and Cherniak, 1960). Another aspect of respiration in obese patients is their need to keep ventilation and respiratory frequency constant against the increased load, which leads to a constant

inspiratory straining and, possibly, to an increased force by the inspiratory muscles ( Domingos-Benício et al., 2003 and Rochester and Enson, 1974). This increased force would require the maintenance of or increase in VT and VE. From this perspective, the weight reduction after surgery could explain the reduction in VT and VE found in this study and could be considered an improvement in respiratory function. However, compared to the control group, the higher VE observed in preoperative obese patients is related to a higher f because there was not a significant difference in VT. Tomich et

al. (2010) found a lower f during incentive spirometry with a volume-oriented device because this device increased the minute ventilation in obese patients after gastroplasty. Tobin et al. (1983a) demonstrated science that individuals with reduced pulmonary compliance increase f to obtain adequate ventilation. This adaptation mechanism probably occurred in our patients. Six months after surgery, there was a significant reduction in VE despite a higher f than in the control group. This reduction is probably related to a small increase in the ventilation demand despite the significant reduction in BMI; individuals remained obese 6 months after surgery. In the presence of increased ventilatory requirements, there are increases in VT of up to 60% of vital capacity. Any other ventilation increase is related to an increase in f ( Cherniack, 1995). Therefore, it is possible that this difference in f is related to increase respiratory impedance.