Forced Vital Capacity: Pilot study of Portuguese data and predictive model

Abstract

The forced vital capacity (FVC) is a reference measure for respiratory support and phonatory production. Objectives: 1) To obtain FVC data of the Portuguese population and 2) To propose a multiple linear regression model to predict the FVC for clinical practice. Methods: 195 subjects participated (97 men with 10-53 years old and 98 women with 11-50 years old). Weight, height and smoking habits were obtained. FVC was measured three times, with a digital and analog spirometer, as well as with and without a nose clip. The largest measure was analyzed with One-Way ANOVA, T-Test, Pearson e Kolmogorov-Smirnov; α=.05. Results: The FVC mean was significantly: 1) higher in males than in females (p=0,000); 2) increased with age in both sexes (p=0,002 and p=0,003), reaching the maximum value at [20-30[ years; 3) increased with weight in men (p=0,004) up to [90-110[ kgs and decreased in women; 4) increased with height in men (p=0,001) and in women up to [1,75-1,85[m and 5) greater in never-smokers than in smokers, in both sexes (p=0,000). The FVC mean was higher when taken with a digital spirometer and with a nose clip occlusion. Conclusion: This study presents FVC values for the Portuguese Caucasian population to be applied in clinical practice in the respiratory and vocal areas. The mathematical model obtained explains 95,8% of the FVC variation.