The aim of this study was to investigate, by means of FOT analysis, the alterations of respiratory mechanics in patient with Interstitial Lung Disease (ILD), with or without diagnose of restrictive dysfunction by spirometry.PATIENT AND METHODS: We analyzed 05 healthy subjects (56,8±14,3 years, 160,6±12,4 cm), 05 patients with ILP and without alterations on spirometry (59,4±13,45 years, 173,3±11,5 cm) and 05 patients with ILD with alterations on spirometry compatible with restrictive dysfunction (57,7±10,27 years, 161±17,7 cm). The forced vital capacity (FVC) and the forced expiratory volume in one second (VEF1) were measured with spirometer. FOT resistive parameters, the zero intercept resistance (R0), mean resistance (Rm), the slope of the impedance’s resistive component(S) were evaluated in the 4–16 Hz frequency range. The mean reactance (Xm) and the dynamic compliance (Cdyn) were obtained in the 4–32 Hz range. Unpaired t-tests were used in comparisons, and at p<0.05 they were assumed to be significant.RESULTS AND DISCUSSION:Comparing R0 and Rm in healthy subjects and ILD patients without alterations in spirometry showed no significantly difference (p>0.05). A comparison between ILD patients without alterations in spirometry and with alterations showed significant differences (p<0.05). This indicates that an increase in resistance could also be occurring in these individuals, together with their restrictive patterns. Indexes of lung homogeneity (S and Xm) showed significantly more negative values in individuals with restrictive patterns when compared to patients without restriction (p<0.03). Cdyn showed the largest difference among the groups. Individuals without restrictive patterns also presented significant alterations compared to the control group (p<0.02).
The results of this study indicate that, besides restrictive alterations and reductions in the homogeneity lung, patients with ILD could also present increased values of respiratory resistance.
The clinical potential of FOT in the evaluation of ILD was confirmed. It can contribute to facilitate the evaluation of these patients, since the exam is noninvasive and needs only passive cooperation.
- Spirometry and FOT parametersControlWithout Disf.With Disf.FVC (L)3.5±1.23.9±0.71.4±0.4FEV1 (L)2.9±0.92.9±0.51.9±0.6R0 (cmH2O/L/s)2.4±1.12.2±0.63.5±0.8Rm(cmH2O/L/s)2.2±1.02.3±0.53.0±0.5S(cmH2O/L/s2)−19.9±25.83.9±12.3−51.1±28.7Xm(cmH2O/L/s)−0.2±0.30.4±0.4−0.8±0.8Cdyn(L/cmH2O)0.04±0.010.02±0.010.01±0.01
P.L. Melo, CNPq, grant monies; FAPERJ, grant monies. Supported by CNPq and FAPERJ.