Espirometria com VEF0,75 aumenta a sensibilidade para o diagnóstico de distúrbio obstrutivo em filhos de mães asmáticas

Abstract

Objective: Compare the sensitivity of spirometry in children of asthmatic mothers by the parameters FEV1 and FEV0.75. Methods: An observational cross-sectional analytical study nested in a cohort of 4,757 pregnant women. Clinical evaluation was performed for the diagnosis of asthma, besides the realization of spirometry in the children of asthmatic mothers, evaluating the following parameters and relationships: FEV1, FVC, FEV1/FVC, FEV0.75 and FEV0.75/FVC. Results: A total of 86 children of asthmatic mothers were included in the study, with age mean of 79.8 ± 1.1 month old. Regarding the breathing pattern there was a predominance of normality. When using FEV1, changes were observed in 26 children, representing 30.3% of the sample. Of these, 17 were classified as restrictive and nine as obstructive. Using the FEV0.75 instead of the FEV1 (and its consequent FEV0.75/FVC) 29 ventilatory tests found changed, representing 33.7%. Of these, 27 were classified as obstructive and only two were restrictive. Of the 16 children diagnosed with asthma, only five had presented obstructive pattern when FEV1 customization spirometry was used. In contrast, when we used FEV0.75, 12 of these patients were considered obstructive. The sensitivity was higher in the spirometric test that used FEV0.75, with even greater negative predictive value. On the other hand the test set for the parameter FEV1 showed greater specificity and higher positive predictive value. Conclusions: Spirometry, though with recognized value in the complementary diagnosis of obstructive disturbance, classically presents limitations in the pediatric population, especially in younger children. We observed a significantly higher sensitivity and negative predictive value when we used FEV0.75 in substitution to the FEV1. As a consequence, the parameter FEV0.75 is probably more effective for the diagnosis of obstructive disorder in patients with clinical history or family history of asthma.