Brazilian studies on pulmonary function in COPD patients: what are the gaps?

Figures & data

Figure 1 Schematic representation of the scope of the current review.

Figure 2 Examples of results for the resistance (R_rs; A) and reactance (X_rs; B) obtained in normal subjects and patients with COPD classified according to the GOLD criteria.

Abbreviation: GOLD, Global Initiative for Chronic Obstructive Lung Disease.

Figure 3 Differences in the diagnostic performance of FOT and spirometric parameters, calculated by the difference between AUCs.

Notes: Note the higher AUC values in the FOT parameters. The significance is shown at the top of the bars: 5, P<0.05; 1, P<0.01. Adapted from Faria et al,⁵⁹ under creative commons license: http://creativecommons.org/licenses/by/2.0/.
Abbreviations: FOT, forced-oscillation technique; AUCs, areas under the curve; Z_4Hz, absolute value of respiratory impedance; C_dyn, dynamic compliance; X_m, mean reactance; R_m, mean resistance; R₀, resistance at the intercept; FEF, forced expiratory flow; FVC, forced vital capacity; FEV₁, forced expiratory volume in 1 second; S, slope of resistance; Fr, resonance frequency.

Figure 4 Mean Z_rs values during the ventilatory cycle in the studied groups.

Notes: *P<0.002; **P<0.0001. Groups were healthy subjects, smokers with normal spirometry, and patients with mild, moderate, severe, or very severe COPD. Adapted with permission from Silva KK, Faria AC, Lopes AJ, de Melo PL. Within-breath respiratory impedance and airway obstruction in patients with chronic obstructive pulmonary disease. Clinics (Sao Paulo). 2015;70(7):461–469.⁶³
Abbreviations: Z_rs, respiratory impedance; GOLD, Global Initiative for Chronic Obstructive Lung Disease; ns, not significant; Z_bi, impedance at beginning of inspiration; Z_i, impedance during inspiration; Z_be, impedance at beginning of expiration; Z_e, impedance during expiration.

Figure 5 Comparisons of the diagnostic accuracy (area under the ROC curve) obtained using the best FOT parameter (BFP) and FOT + best ML methods.

Note: All: all COPD patients; G1: mild airway obstruction; G2: moderate; G3: severe; G4: very severe airway obstruction.
Abbreviations: FOT, forced-oscillation technique; ML, machine learning; ROC, receiver-operating characteristic.

FariaACLopesAJJansenJMMeloPLEvaluating the forced oscillation technique in the detection of early smoking-induced respiratory changesBiomed Eng Online200982219781078

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SilvaKKFariaACLopesAJde MeloPLWithin-breath respiratory impedance and airway obstruction in patients with chronic obstructive pulmonary diseaseClinics (Sao Paulo)201570746146926222814

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