Evaluation of Small Airway Involvement in Patients With Chronic Hypersensitivity Pneumonitis and Its Impact on Exercise Limitation
试验速览
- 阶段
- 不适用
- 状态
- 已完成
- 入组人数
- 27
- 试验地点
- 1
- 主要终点
- Pletismography - forced expiratory volume in 1 second / forced vital capacity (FEV1/FVC) < 0.7, residual volume (VR) and VR/total lung capacity (TLC) values and changes with salbutamol
研究概览
简要总结
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).
详细描述
Hypersensitivity pneumonitis (HP) is a syndrome with variable clinical presentation, in which inflammation in lung parenchyma is caused by inhalation of organic antigens or specific low molecular weight substances in previously sensitized individuals. Systemic symptoms may or not be present. Chronic HP represents the final stage of this disease, where prolonged exposure to a particular antigen would lead to lung fibrosis. The list of new antigens is growing, but the main antigens responsible for this disease are exposure to mold and birds.
Not all exposed individuals develop HP. The pathophysiology involves initial exposure and a subsequent decrease in antigen tolerance. Genetic susceptibility can also modulate the immune response to a specific antigen.
There are no reliable epidemiological data on the incidence or prevalence of HP. Differences in the type of antigen sensitization, lack of standardized diagnostic criteria and underreporting are possible factors. In Mexico, one of the few population surveys showed an estimated incidence of 30 cases per 100000 inhabitants in 2 years (1988-1990); however, there are some bias that limit the extrapolation of data to other contexts.
The patient rarely associates the onset of symptoms with a relevant exposure, making it important to actively search for environmental factors against respiratory complaints. It is believed that intermittent exposure to an antigen, long-term exposure to a small load of antigen or a cumulative effect of multiple episodes of acute exposure can cause chronic HP. It is noteworthy that only a small proportion of patients with a single episode of acute exposure will develop chronic HP.
In chronic HP, the patient complains of dyspnea on exertion and dry cough. Systemic symptoms such as fever and weight loss are rarely reported and may be associated with episodes of acute exposure. Physical examination reveals crackles and less commonly, digital clubbing. Auscultation may reveal the presence of squawks arising from the abrupt opening of small airways. Hypoxemia is found in patients with more severe lung disease.
研究设计
- 研究类型
- Interventional
- 分配方式
- Na
- 干预模型
- Single Group
- 主要目的
- Other
- 盲法
- None
入排标准
- 年龄范围
- 18 Years 至 75 Years（Adult, Older Adult）
- 性别
- All
- 接受健康志愿者
- 否
入选标准
- •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.
排除标准
- •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.
研究组 & 干预措施
Chronic HP patients
Chronic hypersensitivity pneumonitis patients - use of salbutamol
干预措施: Salbutamol (Drug)
结局指标
主要结局
Pletismography - forced expiratory volume in 1 second / forced vital capacity (FEV1/FVC) < 0.7, residual volume (VR) and VR/total lung capacity (TLC) values and changes with salbutamol
时间窗: One day visit
Percentage of VEF1/FVC \< 0.7, residual volume (VR) \>120% predicted and VR/total lung capacity (TLC)\>.45 values and changes with salbutamol
次要结局
- Reactance and impedance of small airways through forced oscillation technique(One day visit)
- Air trapping in expiratory chest CT scans(One day visit)
研究者
Olívia Meira Dias
Medical doctor
University of Sao Paulo General Hospital