Seventy-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.

Objetivo: O presente trabalho dá prosseguimento ao estudo da validade de equações para valores teóricos (VT) para cálculos espirométricos na população brasileira. Foi feita a comparação entre as equações propostas por Mallozzi (VT-M) para população brasileira e as de Polgar (VT-P), utilizadas especialmente na Europa e Estados Unidos. Métodos: Foram analisados os VT medidos em 185 pacientes de ambos os sexos, com idade entre 6 e 17 anos, sendo 89 meninos e 96 meninas. Para cada paciente foi feito o cálculo do VT para CVF, VEF 1 e FEF 25-75 segundo as equações de Mallozi VT-M e de Polgar VT-P. Em seguida foram comparados os laudos obtidos por um e por outro, segundo o Consenso de Espirometria da SBPT. Resultados: O VT-M para CVF é 0,38% maior para os meninos e 2,19% para as meninas que o calculado segundo Polgar. Os VT-P para o VEF 1 são 6,67% (p < 0,05) menores para as meninas e 7,26% para os meninos. Para o FEF 25-75 os valores diferem apenas em 0,35 e 0,43% para cada um dos sexos, sem significância estatística. Conclusão: Os VTs de CVF e VEF 1 para crianças brasileiras, avaliados segundo Mallozzi, diferem significativamente quanto aos VTs de Polgar. Como conseqüência, encontramos, utilizando as equações de Mallozzi, tendência maior em diagnosticar dificuldade obstrutiva e menor em achados de insuficiência ventilatória restritiva. (J Pneumol 2002;28(3):125-130) Comparison between the theoretical values for spirometric data in children determined by Mallozi's and Polgar's equations Objective: This paper is a continuation of the study on the validity of equations of predicted value (PV) for the Brazilian population. A comparison was made between the equations proposed by Mallozi and byPolgar for the Brazilian population, which are mainly used in the United States and Europe. Methods: PVs of 185 patients of both sexes (89 boys and 96 girls), ages between 6 and 17 years, were analyzed. For each subject, the PVs for forced vital capacity (FVC), forced expiratory volume at 1 sec. (FEV 1 ), and the medium expiratory flow (MEF) were calculated according to the equations proposed by Mallozi and Polgar. Results were compared. Diagnoses were made according to the Brazilian Consensus of Spirometry. Results: The PV-M for FVC is 0.38% higher for boys and 2.19% higher for girls than that determined by Polgar. The PV-P for FEV 1 is 6.67% (p < 0.05) lower for girls, suggesting an underassessment of the obstructive impairment. For boys, a mean lower value of 7.26% as compared to the VT-M is at the limit of significance (0.05 < p < 0.01). No significant difference between the two equations analyzed was found for MEF. Conclusions: The PVs for CVF and VEF 1 for Brazilian children, according to Mallozzi, are significantly different when compared to those published by authors like Polgar. As a result, the authors found that Mallozzi's equations are more likely to detect obstructive impairment and less likely to diagnose restrictive ventilatory insufficiency.ARTIGO ORIGINAL