Contribution of flow-volume curves to the detection of central airway obstruction.
OBJECTIVE
To assess the sensitivity and specificity of flow-volume curves in detecting central airway obstruction (CAO), and to determine whether their quantitative and qualitative criteria are associated with the location, type and degree of obstruction.


METHODS
Over a four-month period, we consecutively evaluated patients with bronchoscopy indicated. Over a one-week period, all patients underwent clinical evaluation, flow-volume curve, bronchoscopy, and completed a dyspnea scale. Four reviewers, blinded to quantitative and clinical data, and bronchoscopy results, classified the morphology of the curves. A fifth reviewer determined the morphological criteria, as well as the quantitative criteria.


RESULTS
We studied 82 patients, 36 (44%) of whom had CAO. The sensitivity and specificity of the flow-volume curves in detecting CAO were, respectively, 88.9% and 91.3% (quantitative criteria) and 30.6% and 93.5% (qualitative criteria). The most prevalent quantitative criteria in our sample were FEF50%/FIF50% ≥ 1, in 83% of patients, and FEV1/PEF ≥ 8 mL · L(-1) · min(-1), in 36%, both being associated with the type, location, and degree of obstruction (p < 0.05). There was concordance among the reviewers as to the presence of CAO. There is a relationship between the degree of obstruction and dyspnea.


CONCLUSIONS
The quantitative criteria should always be calculated for flow-volume curves in order to detect CAO, because of the low sensitivity of the qualitative criteria. Both FEF50%/FIF50% ≥ 1 and FEV1/PEF ≥ 8 mL · L(-1) · min(-1) were associated with the location, type and degree of obstruction.
Northern Lisbon Hospital Center, Department of Pulmonology, Lisbon, Portugal.
Liliana Bárbara Perestrelo de Andrade e
LB
Raposo
António
A
Bugalho
Maria João Marques
MJ
Gomes
D000402:Airway Obstruction / Q000150:complications / Q000175:diagnosis*; D001999:Bronchoscopy; D003430:Cross-Sectional Studies; D004417:Dyspnea / Q000175:diagnosis* / Q000209:etiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012123:Pulmonary Ventilation / Q000502:physiology; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D013147:Spirometry