Chest mechanics in morbidly obese non-hypoventilated patients

AbstractSeventy-seven patients with morbid obesity, body mass index (BMI) 40–69·9 kg m−2, who were candidates for gastroplasty, were studied in our laboratory as part of a pre-operative survey. They had no complaints other than obesity and were not cyanotic. A group of 28 lean subjects (BMI 20–29·8 kg m−2) who were candidates for abdominal surgery, without any respiratory complaint, were included as controls. For each patient a pulmonary function test was performed, measuring slow vital capacity with expiratory residual volume (ERV), forced vital capacity (flow/volume) and maximal voluntary ventilation (MVV).In obese patients the MVV is reduced as BMI increases. This results in the reduction of expiratory flows and volumes. Forced expiratory volume in 1 sec (FEV1) is reduced in proportion to the FVC reduction and is related to MVV. It is suggested that the main consequence of the burden of the chest wall by increased adipose mass is a reduction in its compliance, making inspiration increasingly difficult, and resulting in lower static volumes and flows

Novos valores de referência para espirometria forçada em brasileiros adultos de raça branca New reference values for forced spirometry in white adults in Brazil

OBJETIVO: Descrever novas equações de referência para a espirometria em adultos brasileiros saudáveis que nunca fumaram, e comparar os valores previstos atuais com os valores derivados em 1992. MÉTODOS: Equações e limites de referência foram derivados em 270 homens e 373 mulheres, habitantes de oito cidades brasileiras, por espirômetro. A idade variou de 20 a 85 anos nas mulheres e 26 a 86 anos nos homens. Os exames seguiram as normas recomendadas pela Sociedade Brasileira de Pneumologia e Tisiologia. Os limites inferiores foram derivados pela análise do 5º percentil dos resíduos. RESULTADOS: Os valores previstos para capacidade vital forçada (CVF), volume expiratório forçado no primeiro segundo (VEF1) e para as relações VEF1/CVF e VEF1/volume expiratório forçado nos primeiros seis segundos (VEF6) se ajustaram melhor em regressões lineares. Os fluxos ajustaram-se melhor em equações logarítmicas. Em ambos os sexos, maiores estaturas resultaram em menores valores para as relações VEF1/CVF, VEF1/VEF6 e fluxos/CVF. Os valores de referência do VEF1 e da CVF, no presente estudo, foram maiores do que aqueles derivados para adultos brasileiros em 1992. CONCLUSÃO: Novos valores previstos para a espirometria forçada foram obtidos em uma amostra da população brasileira de raça branca. Os valores são maiores do que os obtidos em 1992, provavelmente em decorrência de fatores técnicos.<br>OBJECTIVE: To describe spirometric reference equations for healthy Brazilian adults who have never smoked and to compare the predicted values with those derived in 1992. METHODS: Reference equations for spirometry were derived in 270 men and 373 women living in eight cities in Brazil. Ages ranged from 20 to 85 years in women and from 26 to 86 years in men. Spirometry examinations followed the recommendations of the Brazilian Thoracic Society. Lower limits were derived by the analysis of the fifth percentiles of the residuals. RESULTS: Forced vital capacity (FVC), forced expiratory volume in one second (FEV1), FEV1/FVC and FEV1/forced expiratory volume in six seconds (FEV6) were best fitted by linear regression. Flows were best fitted using log equations. For both genders, greater height resulted in lower values for FEV1/FVC, FEV1/FEV6 and flow/FVC ratios. The reference values for FEV1 and FVC in the present study were higher than those derived for Brazilian adults in 1992. CONCLUSION: New predicted values for forced spirometry were obtained in a sample of white Brazilians. The values are greater than those obtained in 1992, probably due to technical factors