Title: Difference Between The Slow Vital Capacity And Forced Vital Capacity: Predictor Of Hyperinflation In Patients With Airflow Obstruction
Abstract:Introduction: The aim of our study was to assess the relation between the difference in the vital capacity (dVC) measured by means of forced manoeuvres (forced vital capacity FVC ) and slow (expirator...Introduction: The aim of our study was to assess the relation between the difference in the vital capacity (dVC) measured by means of forced manoeuvres (forced vital capacity FVC ) and slow (expiratory vital capacity EVC -) and the presence of air trapping. We also studied the predictive value of this difference as a marker of the degree of air trapping. Methods: 162 consecutive individuals with suspected airflow obstruction comprised the study cohort. A simple spirometry and a determination of lung volumes by plethysmography were performed in all patients. The patients were classified in not obstructive, mild, moderate and severe obstructive. We randomly divided the 124 obstructive patients in two groups: regression group (n=94) and validation group (n=30). A multiple regression analysis was carried out, in which the hyperinflation (RV/TLC) composed the dependent variable and age, body mass index (BMI), forced expiratory volume in the first second (FEV1), and dVC composed the independent variables in the model. We subsequently verified the equation in the validation group. Results: Thirty-eight patients were non-obstructive, 53 presented with mild obstruction, 39 moderate and 32 severe obstruction. The FVC was a 3,1% lower than the EVC in non-obstructive individuals, a 5,1% lower in those with mild obstruction, 10% lower in the moderate obstructive and a 16,8% lower in the severe obstructive groups. In the regression analysis FEV1 and dVC explained the 52% of the variability of the hyperinflation. Conclusions: The FVC is lower than the EVC either in normal individuals or in obstructive patients. The difference between the FVC and the EVC increases with the degree of obstruction. Hyperinflation in patients with airway obstruction is determined by the degree of obstruction (FEV1) and by the difference in the vital capacity between forced and slow manoeuvres.Read More
Publication Year: 2005
Publication Date: 2005-01-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 11
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