Small Airway Involvement in Patients With Chronic Hypersensitivity Pneumonitis

• Status: Completed
• Trial end date: 2017-11-20
• Target enrollment: 0
• Participant gender: All

Summary

Hypersensitivity pneumonitis (HP) is a syndrome with variable clinical presentation in which lung inflammation is caused by inhalation of specific organic antigens or low molecular weight particles in previously sensitized individuals. Systemic symptoms may or may not be present. Chronic HP represents the final stage of the disease, caused by prolonged exposure to a particular antigen, leading to pulmonary fibrosis. In chronic HP, pulmonary function tests (PFTs) commonly present a restrictive ventilatory pattern, with decreased diffusion of carbon monoxide (DLCO). Some patients can also have obstructive disorders with expiratory flow limitation, due to obstruction of the small airways typically caused by bronchiolar involvement in this pathology. However, PFTs are relatively insensitive for detecting small airway involvement when there is concomitant interstitial fibrosis. First, conventional PFTs may be normal in patients with small airway involvement, since they contribute to less than 30% of the total airway resistance. In addition, damage to the small airways in HP is generally occurring parallel to areas of focal fibrosis - even when small airways are involved, these regions can be completely ignored, since they are excluded from ventilation. In summary, traditional PFTs are not sufficiently sensitive to detect diffuse small airway involvement in these diseases. In these cases, other functional tests, such as forced oscillation technique (FOT) and high resolution computer tomography (HRCT) scans of the chest with expired studies, could be used for this purpose.

This will be a cross-sectional study, which will include the following evaluations in 28 patients with HP recruited from our clinic:

• Clinical variables: (A) demographic and anthropometric data; (B) Clinical data: Onset of symptoms and time of diagnosis

C) Dyspnea score:

D) Smoking: * Current or former smoker * Smoking history (number of cigarettes smoked per day and for how long);

• Spirometry with forced and slow maneuvers before and after bronchodilator (salbutamol);

• Plethysmography to measure lung volumes;

• Diffusion capacity of carbon monoxide (DLCO);

• High-resolution chest CT with expiratory scans;

• Six-minute walk test;

• Cardio-respiratory test using a maximal incremental treadmill.

• Forced oscillation technique (FOT).

• Phase: N/A
• Accepts Healthy Volunteers?: No

Details

• Lead Sponsor: University of Sao Paulo General Hospital
• Treatments: Albuterol

Criteria

Inclusion Criteria:

• Diagnosis of chronic hypersensitivity pneumonitis confirmed by:

• patients with known exposure to antigen, tomographic criteria and absence of other diagnoses;

• confirmation with histology obtained by transthoracic biopsy, surgical biopsy or bronchoalveolar lavage with lymphocytosis above 30%;

• Age between 18 to 75 years;

• Clinically stable (no exacerbations or hospitalizations related to the underlying disease) for at least 6 weeks;

• Compliance with signing an informed consent for participation in the project.

Exclusion Criteria:

• Patients with FEV1 and / or DLCO <30% predicted;

• Patients using supplemental oxygen;

• Previous diagnosis of asthma or COPD;

• Pregnant women;

• Musculoskeletal disorders that limit exercise;

• Another medical condition that might interfere with the execution of tests;

• Current or past smoking history with tobacco intake greater than 30 pack-years;

• Severe heart disease functional class New York Heart Association (NYHA) III-IV) and / or decompensated hear failure.