A New Telemedicine System for the Home Monitoring of Lung Function in Patients with Obstructive Respiratory Diseases

Abstract

The conventional pulmonary function tests are based on spirometry, which unfortunately doesn't produce accurate and reproducible results if performed without the supervision of specially trained staff. We recently showed that forced oscillation technique is best suited for the homemonitoring of respiratory patients. The aim of this study was to develop a real-time data processing algorithm for the automatic unsupervised assessment of the lung obstruction, a network architecture for the data transmission and a webbased application for the storage and management of the data. The results demonstrated a high reliability of the algorithm, the robustness of the data communication protocols and the effectiveness of the data management web portal. In conclusion, our system allows a reliable automatic home monitoring of lung obstruction and it may improve the efficacy and efficiency of the management of respiratory patients through an improved tailoring of the clinical treatments and an early detection of exacerbations.

Ventilation heterogeneity in obesity

“…Modeling and experimental studies have suggested that low-frequency dependence of resistance reflects ventilation heterogeneity in the periphery of lung (10,13,28,30,39,42,47). We could not measure resistance below 5 Hz but we think it reasonable to assume that increased R [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] reflects an increased heterogeneity, although we cannot state at which level of airway tree. Regions with different time constants as a result of micro-atelectases, hypoventilation, or nonuniform distribution of pleural pressure (3,4,9,19,20,22,33,38,41,54) are expected to produce parallel heterogeneities indeed, although also the interplay between increased chest wall and parenchymal stiffness and gas inertia in obesity can promote serial heterogeneities, as reported in animal models under different conditions (1,27).…”

“…Single-breath lung diffusion capacity for carbon monoxide (DL CO) was measured following the ATS/ERS recommendations (31). Predicted values were from Quanjer et al (43) for spirometry and lung volumes and from Cotes et al (7) for DL CO. Respiratory impedance was measured by a forced oscillation system previously described (8,14,15). Sinusoidal pressure oscillations (5, 11, and 19 Hz; ϳ2 cmH 2O amplitude) were generated by a 16-cm-diameter loudspeaker (model CW161N, Ciare, Italy) and applied at the mouth during tidal breathing.…”

“…Respiratory resistance and reactance were computed by a least-squares algorithm (25,26) at 5 Hz (R 5 and X5, respectively) and 19 Hz (R19 and X19, respectively). Artifacts due to glottis closure or expiratory airflow limitation were avoided by discarding breaths showing any of the following features: 1) tidal volume Ͻ0.1 liter or Ͼ2.0 liter; 2) difference between measured flow oscillation and ideal sine wave with the same Fourier coefficients Ͼ0.2 (34); and 3) ratio of minimum to average X 5 Ͼ 3.5 (14). The same breaths were used to measure tidal volume (VT), breathing frequency (BF), and minute ventilation (V E).…”

“…Ventilation heterogeneity was inferred from the variability of the frequency dependence of respiratory resistance measured by forced oscillation technique. The underlying assumptions were that ventilation distribution can be assessed from the difference in respiratory resistance between 5 and 19 Hz (R [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] ) (10,13,28,30,39,42,47) and its variability over time as estimated from the short-term interquartile range of probability density (R 5-19 _ IQR ) can provide a better estimate than mean value (12,49,50).…”

Telemonitoring in Chronic Obstructive Pulmonary Disease (CHROMED). A Randomized Clinical Trial

“…FOT measurements were cleaned automatically from artefacts using previously published filtering rules 29 and automatically sent to the study server. An algorithm generated respiratory alerts if a trend of worsening was detected in at least one of the following FOT parameters measured at 5Hz: inspiratory resistance (Rinsp), inspiratory reactance (Xinsp) or the difference between inspiratory and expiratory reactance (∆Xrs), an index of the presence of tidal expiratory flow limitation 30,31 .…”