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خرید پکیج
تعداد آیتم قابل مشاهده باقیمانده : 3 مورد
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Pulmonary function testing in the evaluation of chronic dyspnea

Pulmonary function testing in the evaluation of chronic dyspnea
Pulmonary function tests
Abnormality Interpretation Further testing
Airflow obstruction with complete reversibility following inhaled bronchodilator Likely asthma: Institute therapy based on severity of obstruction according to current guidelines. Reassess dyspnea and spirometry after treatment trial.
Airflow obstruction that is irreversible or incompletely reversible following bronchodilator Likely COPD, especially in smokers. Chronic/severe asthma can cause airflow limitation that is incompletely reversible with bronchodilator, but may improve over time with inhaled or oral glucocorticoid therapy. Less commonly bronchiolitis or bronchiectasis. Reassess dyspnea and spirometry after treatment trial/pulmonary rehabilitation/smoking cessation/removal of allergen exposure.
Bronchiolitis should be suspected in patients with poor response to therapy for asthma/COPD or with the combination of airflow limitation and impaired gas transfer, may need HRCT to look for radiographic evidence of bronchiolitis or bronchiectasis.
Normal (expiratory) spirometry

Normal spirometry does not exclude asthma or upper airway obstruction.

Depending on clinical suspicion:
  • Review inspiratory and expiratory flow volume loop for upper airway flow limitation
  • Obtain bronchoprovocation challenge (eg, methacholine, mannitol, exercise)
  • Obtain lung volumes, DLCO, SpO2 with exercise (if not already done)
Positive bronchoprovocation: Asthma is likely cause of dyspnea. Reassess after treatment trial.
Bronchoprovocation negative but flow volume loop has slowing on inspiratory phase suggesting possible upper airway obstruction; direct visualization needed to confirm.
Refer to "Lung volumes normal but DLCO reduced and/or SpO2 <95% or decreases by >4% with exertion" below.
Reduced FVC with normal FEV1/FVC Evaluate for restrictive process (pleural, chest wall, or neuromuscular), interstitial lung disease, or air trapping.
  • Obtain/review lung volumes and DLCO
  • Examine CXR re: pleural effusion, kyphoscoliosis, or hemidiaphragm elevation
Lung volumes (FVC and TLC) confirm restrictive pattern, DLCO normal or slightly low: Consider pleural, chest wall, and neuromuscular disease.
  • Obtain MEP, MIP, MVV
  • Review imaging
  • Consider fluoroscopy for diaphragm dysfunction
Reduced DLCO and lung volumes suggest interstitial lung disease or emphysema: Consider HRCT.
Increased RV or FRC suggests airtrapping (eg, due to emphysema, LAM, bronchiolitis) as a cause of low FVC. HRCT can identify emphysema, cystic changes of LAM, mosaic pattern suggestive of bronchiolitis.
Lung volumes normal but DLCO reduced and/or SpO2 <95% or decreases by >4% with exertion Possibilities include early ILD and pulmonary vascular disease: Obtain HRCT, BNP, and echocardiogram with Doppler assessment of PA pressures. If no ILD on HRCT and BNP and echocardiogram suggest pulmonary hypertension, may need PA catheterization.
Normal flow volume loop, lung volumes, DLCO, ambulatory SpO2, and bronchoprovocation Increasing likelihood of nonrespiratory cause of dyspnea. Obtain/review CXR, echocardiogram. May need CPET.
COPD: chronic obstructive pulmonary disease; HRCT: high resolution computed tomography; DLCO: diffusing capacity of the lungs for carbon monoxide; SpO2: pulse oxygen saturation; FVC: forced vital capacity; FEV1: forced expiratory volume in one second; CXR: chest radiograph; TLC: total lung capacity; MEP: maximal expiratory pressure; MIP: maximal inspiratory pressure; MVV: maximal voluntary ventilation; RV: right ventricular; FRC: functional residual capacity; LAM: lymphangioleiomyomatosis; ILD: interstitial lung disease; BNP: brain natriuretic peptide; PA: pulmonary artery; CPET: cardiopulmonary exercise test.
Graphic 104821 Version 3.0

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