This paper emphasizes the influence of micro mechanisms of failure of a cellular material on its phenomenological response. Most of the applications of cellular materials comprise a compression loading. Thus, the study focuses on the influence of the anisotropy in the mechanical behavior of cellular material under cyclic compression loadings. For this study, a Digital Image Correlation (DIC) technique (named Correli) was applied, as well as SEM (Scanning Electron Microscopy) images were analyzed. The experimental results are discussed in detail for a closed-cell rigid poly (vinyl chloride) (PVC) foam, showing stress-strain curves in different directions and why the material can be assumed as transversely isotropic. Besides, the present paper shows elastic and plastic Poisson's ratios measured in different planes, explaining why the plastic Poisson's ratios approach to zero. Yield fronts created by the compression loadings in different directions and the influence of spring-back phenomenon on hardening curves are commented, also.

OBJECTIVE: To determine whether preoperative inspiratory muscle training is able to attenuate the impact of surgical trauma on the respiratory muscle strength, in the lung volumes, and diaphragmatic excursion in obese women undergoing open bariatric surgery. DESIGN: Randomized controlled trial. SETTING: Meridional Hospital, Cariacica/ES, Brazil. SUBJECTS: Thirty-two obese women undergoing elective open bariatric surgery were randomly assigned to receive preoperative inspiratory muscle training (inspiratory muscle training group) or usual care (control group). MAIN MEASURES: Respiratory muscle strength (maximal static respiratory pressure - maximal inspiratory pressure and maximal expiratory pressure), lung volumes, and diaphragmatic excursion. RESULTS: After training, there was a significant increase only in the maximal inspiratory pressure in the inspiratory muscle training group. The maximal expiratory pressure, the lung volumes and the diaphragmatic excursion did not show any significant change with training. In the postoperative period there was a significant decrease in maximal inspiratory pressure in both the groups. However, there was a decrease of 28% in the inspiratory muscle training group, whereas it was 47% in the control group. The decrease in maximal expiratory pressure and in lung volumes in the postoperative period was similar between the groups. There was a significant reduction in the measures of diaphragmatic excursion in both the groups. CONCLUSION: The preoperative inspiratory muscle training increased the inspiratory muscle strength (maximal inspiratory pressure) and attenuated the negative postoperative effects of open bariatric surgery in obese women for this variable, though not influencing the lung volumes and the diaphragmatic excursion.

O objetivo deste estudo foi comparar o efeito da pressão positiva expiratória (EPAP, na sigla em inglês) e da inspirometria de incentivo a fluxo sobre a função pulmonar após o bypass gástrico em Y de Roux por videolaparoscopia. Participaram 28 mulheres, não-tabagistas e não-pneumopatas, com índice de massa corporal entre 35 e 50 kg/m², submetidas à cirurgia bariátrica. Todas foram avaliadas por espirometria, cirtometria toracoabdominal e quanto à mobilidade diafragmática no pré e segundo dia de pós-operatório (o tempo de internação foi de 2 dias). Foram divididas em dois grupos, GI - grupo inspirômetro (n=13) e GE, grupo EPAP (n=15). A fisioterapia foi iniciada no dia da cirurgia, cada técnica, inspirometria ou EPAP, com duração de 15 minutos; a fisioterapia motora foi padronizada para ambos os grupos. No pós-operatório, houve redução similar nos dois grupos das variáveis: capacidade vital, volume de reserva inspiratório, capacidade vital forçada e ventilação voluntária máxima. Não houve alteração nos valores do volume corrente no GI e volume de reserva expiratório no GE. A mobilidade diafragmática e a mobilidade toracoabdominal foram menos prejudicadas no GI. No pós-operatório da cirurgia bariátrica por videolaparoscopia, a inspirometria de incentivo a fluxo exerceu melhores efeitos na manutenção do volume corente, na mobilidade diafragmática e toracoabdominal, enquanto a EPAP foi mais eficaz no restabelecimento do volume de reserva expiratório.

The aim of this study was to compare the effect of expiratory positive airway pressure (EPAP) and flow-oriented incentive spirometry on pulmonary function after laparoscopic Roux-en-Y gastric bypass surgery. Twenty-eight non-smoking women, with no lung disease and body mass index of 35 to 50 kg/m², undergoing laparoscopic gastric bypass surgery (hospitalized for two days) were assessed by spirometry, thoracoabdominal cirtometry and as to diaphragmatic motion prior to, and on the second post-operative day. Before surgery patients were divided into two groups, SG - spirometer group (n=13), and EG - EPAP group (n=15). Motor physical therapy was standardized for both groups; respiratory therapy (both modalities) started on the day of surgery, in 15-minute sessions. Post-operative results showed similar reduction, in both groups, in the values of vital capacity, forced vital capacity, maximum voluntary ventilation, and inspiratory reserve volume. No changes were found in tidal volume values in SG, neither in expiratory reserve volume in EG. Diaphragmatic and thoracoabdominal motion were less harmed in SG. After bariatric surgery thus incentive spirometry had better effect in maintaining tidal volume, as well as on diaphragmatic and thoracoabdominal motion; while EPAP proved more efficient in re-establishing expiratory reserve volume in the postoperative period.

INTRODUCTION: Obesity can cause deleterious effects on respiratory function and impair health and quality of life. OBJECTIVE: To evaluate the effects of obesity on the pulmonary function of adult women. METHODS: An obese group, constituted of 20 women between 20 and 35 years old with a BMI of 35 - 49.99 kg/m² who were non-smokers and sedentary and had no lung disease were recruited. The non-obese group consisted of 20 women between 20 and 35 years old who were sedentary and non-smokers and had no lung disease and a body mass index between 18.5 and 24.99 kg/m². Spirometry was performed in all subjects. The statistical analysis consisted of parametric or non-parametric tests, depending on the distribution of each variable, considering p < 0.05 to be statistically significant. RESULTS: The obese group presented a mean age of 25.85 ± 3.89 years and a mean BMI of 41.1 ± 3.46 kg/m², and the non-obese group presented a mean age of 23.9 ± 2.97 years and a mean body mass index of 21.91 ± 1.81 kg/m². There were no significant differences between the obese group and the non-obese group as to the age, vital capacity, tidal volume, forced vital capacity, and forced expiratory volume in one second. However, the obese group presented a greater inspiratory reserve volume (2.44 ± 0.47 L vs. 1.87 ± 0.42 L), a lower expiratory reserve volume (0.52 ± 0.32 L vs. 1.15 ± 0.32 L), and a maximal voluntary ventilation (108.5 ± 13.3 L/min vs. 122.6 ± 19.8 L/min) than the non-obese group, respectively. CONCLUSION: The alterations evidenced in the components of the vital capacity (inspiratory reserve volume and expiratory reserve volume) suggest damage to the chest mechanics caused by obesity. These factors probably contributed to a reduction of the maximal voluntary ventilation.