Airway obstruction pulmonary function tests

Spirometry Measurement of inhaled and exhaled volumes and flow rates of gas from the lungs. Pulmonary function tests obtained from spirometry are used to aid in the diagnosis of obstructive and restrictive airway diseases. 

In another accidental exposure of five chlorine plant workers and 13 nonworkers, rales, dyspnea, and cyanosis were observed in the most heavily exposed and cough was present in nearly all the patients. Pulmonary function tests 24—48 hours after exposure showed airway obstruction and hypoxemia these conditions cleared within 3 months except in four of the chlorine workers, who still showed reduced airway flow and mild hypoxemia after 12-14 months. ... 

At age 12, the patient was admitted with acute chest pain from a left spontaneous pneumothorax (air within the pleural cavity).This required hospitalization and chest tube insertion, but he recovered without sequelae. After the resolution of this problem, pulmonary function testing revealed findings of both severe airway obstruction and destruction of alveolar lung tissue, consistent with emphysema. No further pulmonary problems occurred until the patient was age 16 years, when he developed occasional episodes of bronchospasm (spasmodic contraction of the smooth muscles of the bronchus). Pulmonary function studies at that time, though improved from those immediately following his pneumothorax, still revealed combined obstructive and destructive lung disease. 

Pulmonary function tests (PFTs) are not helpful (Traub et al, 2002 Pherwani et al, 1989). A study of school children exposed to a chlorine gas leak reported a predominantly obstructive pattern on PFTs. This could be explained by congestion and edema narrowing the eentral airways rather than smaller airways. 

IV. Diagnosis requires a careful occupational history. Pulmonary function testing may document an obstructive deficit or may be normal. Variable airflow or changing measures of airway reactivity (methacholine or histamine challenge) temporally linked to exposure strongly support the diagnosis of isocyanate-induced asthma. 

When constrictive bronchiolitis occurs with no identifiable cause, it is referred to as cryptogenic constrictive bronchiolitis (36). It is rare and occurs mostly in women. Patients present with persistent cough and worsening dyspnea. Basilar inspiratory crackles may be heard on auscultation of the lungs in some patients. Progressive airway obstruction, often associated with air trapping, is seen by pulmonary function testing in the majority of affected patients. 

Pulmonary function test (PFT) abnormalities occur frequently following allogeneic BMT. A decreased carbon monoxide diffusion (DLco) develops in up to 83% and restrictive and obstructive ventilatory defects in up to 35% and 23%, respectively, of allogeneic BMT recipients (3). Significant mucosal injury occurs in about 75% of BMT recipients. Upper airway inflammation due to mucositis may lead to laryngeal edema, dysphagia, and aspiration pneumonia. Life-threatening upper airway complications are more common in children. 

Three anatomic patterns of TBA exist, each with distinct pulmonary function test characteristics (i) proximal trachea, ii) mainstem bronchi, and (Hi) distal airways. Proximal disease limits expiratory airflows, producing flow-volume loop changes consistent with extrathoracic upper airway obstruction. Mainstem bronchial disease affects large airways flow, decreasing FEVl/FWC ratio. In contrast, distal airway involvement results in decreased small airway or FEF 25 to 75 flows (56). Bronchoscopically, TBA appears as submucosal plaques or diffuse infiltration in 44% cases, nodular disease in 28%, and circumferential lesions in 28% (58). 

Evaluation of physiotherapy interventions only with pulmonary function tests appears to be inadequate for significant conclusions. However, it is known that mucus retention has a strong impact on pulmonary function and gas exchange. Severe mucus retention can cause an acute decrease in VC, forced VC, flow rates, as well as Sao2. Patients with severe airway obstruction have more difficulties expectorating mucus. Patients with ineffective cough and low VCs are in extreme respiratory distress in the presence of secretion accumulation. A correct evaluation of pulmonary function and cough parameters may predict a successful respiratory physiotherapy treatment. 

Pulmonary function tests can show restrictive, obstructive, or mixed defect in late disease. An airway obstruction is frequent in the subacute and chronic phase in combination with restrictive pattern. 

Pulmonary function tests reveal a restrictive pattern in early disease. In the acute phase, a reduction in lung volume, carbon monoxide diffusing capacity, and static lung compliance are common. Some patients also show evidence of small airway obstruction. 

A number of patients who have persistent airflow obstruction exhibit considerable variation in airways resistance and hence in their benefit from bronchodilators drugs for asthma. It is important to recognise the coexistence of asthma with chronic obstructive pulmonary disease in some patients, and to assess their responses to bronchodilators or glucocorticoids over a period of time (as formal tests of respiratory function may not reliably predict clinical response in this setting). 

As with other obstructive pulmonary diseases (e.g., asthma), spirometric tests will indicate a decrease in FEVj and an increase in the total forced expiratory time (the total time required to exhale the entire vital capacity of the lung). In emphysema, all of these pulmonary function parameters are altered due to a loss of the elastic recoil properties of the lung and a collapse of the intrathoracic airways during forced expiration, both of these phenomena being caused by the destruction of the interstitial connective tissue. 

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