Detection of air trapping in patients with clinical suspicion of Chronic Obstructive Pulmonary Disease and normal spirometry

Detección de atrapamiento aéreo en pacientes con sospecha clínica de enfermedad pulmonar obstructiva crónica y espirometría normal

Objetives: to determine changes in lung volumes and oscillometry in symptomatic patients with a history of exposure and classified by spirometry as normal or with slight obstruction, with the aim of establishing whether there is a correlation between clinical findings, plethysmography, and oscillometry with spirometry in diagnosing obstruction, and whether it is possible to achieve early diagnosis of COPD by plethysmography and oscillometry in patients with clinical suspicion of the disease.

Materials and methods: a correlation study was carried out, in which 214 patients with clinically suspected COPD from San Ignacio University Hospital (Bogota, Colombia) were collected during the year 2010. A questionnaire of symptoms, spirometry, lung volume measurements, and impulse oscillometry were carried out. 

Results: 214 patients with clinically suspected COPD were collected, 27% of whom had spirometry consistent with obstruction. With regard to lung volumes, 87% had increased residual capacity consistent with air entrapment, and 69% showed increased residual functional capacity with regard to hyperinflation. Resistances were measured by oscillometry, and 22% had increased resistances. The correlation between spirometry and lung volumes was very low, as was also the case with resistances.

Conclusion: it is possible to find air entrapment early in patients with clinically diagnosed COPD, even before the appearance of spirometric abnormalities.