Diagnosing obstructive lung disease

Evaluation of obstructive lung disease with vibration response imaging

As optimal treatment and prognosis differ between asthma and COPD, a new diagnostic approach to differentiating between the two disorders would be clinically desirable. We evaluated the utility of vibration response imaging in differentiating between asthma and COPD. Sixty-six subjects with asthma or COPD were recorded, before and after the administration of a short-acting bronchodilator, using a computerized lung sound analysis device. Gray-scale images of breath sound distribution in the lungs, quantitative data in breath sound graphs (timing, amplitude) and automatic crackle and wheeze detection programs were used to differentiate between asthma and COPD subjects. Imaging data were compared with the clinical diagnosis, made by the standard methods (medical history, physical examination, and spirometric indices). Blinded evaluation of images demonstrated a significantly higher rate of improvement in image dynamics, shape and overall improvement following bronchodilator in subjects with asthma compared with those with COPD. Quantitative data showed distinct patterns in timing and amplitude for these two pathologies. Combined analyses based on qualitative image evaluation and quantitative data demonstrated an overall 85% accuracy (84% for asthma, 86% for COPD) in differentiating between asthma and COPD. Combined qualitative and quantitative evaluations of lung sounds are quite sensitive in distinguishing between lung sound recordings of COPD and asthma individuals. Lung sound features of synchronization in timing and intensity provide objective data that may further differentiate these two airway disorders.

Stepwise health surveillance for bronchial irritability syndrome in workers at risk of occupational respiratory disease

OBJECTIVES

Questionnaires, lung function tests, and peak flow measurements are widely used in occupational health care to screen for subjects with respiratory disease. However, the diagnostic performance of these tests is often poor. Application of these tests in a stepwise manner would presumably result in a better characterisation of subjects with respiratory disease.

METHODS

Cross sectional data from workers exposed to acid anhydrides, to laboratory animals, and to flour dusts were used. Sensitivity and specificity were calculated from cross tables of different (combinations of) tests for bronchial hyperresponsiveness and bronchial irritability in the past four weeks (BIS). From sensitivity and specificity likelihood ratios were computed and change in probability of BIS was calculated.

RESULTS

The prevalence of BIS was 7%, 7%, and 5%, respectively. In all groups questionnaire data provided excellent sensitivity but poor specificity, which was inherent on the broad definition of symptoms. Adding the forced expiratory volume in one second/forced vital capacity (FEV1/FVC) ratio yields almost perfect specificity, and peak expiratory flow (PEF) variability is intermediate in populations in which smoking induced or non-allergic respiratory diseases predominates. In occupational groups in which asthma is a problem, adding PEF measurements will optimise sensitivity and specificity in detection of BIS. The probability of BIS for subjects with a negative combined test outcome was lower than the probability before testing. Subjects with a positive combined test outcome had a probability of BIS after the tests at least three times the probability before.

CONCLUSIONS

Combined testing yields better sensitivity and specificity. An advantage of combined testing is an economy in the effort to screen for subjects with BIS. Combined testing resulted in more detailed estimation of the probability of BIS.

Asthma: An Important Disease to Otolaryngologists — Part I: Suspecting and Diagnosing Asthma

Asthma is a chronic inflammatory disease of the lower respiratory tract which is triggered by exposure to allergens or other airway irritants. This inflammation results in airway hyperresponsiveness, bronchial muscle spasm, mucous gland hypersecretion and mucosal edema, which combine to create symptoms such as cough, wheezing and respiratory distress. Because the inflammatory process is highly variable, asthma is a disorder with many possible presentations. It may therefore proceed for years without clinical recognition, and may challenge the most astute diagnostician.

It is important for otolaryngologists to be able to suspect, diagnose and treat asthma. This is so because asthma is a common disease in the otolaryngologic patient population, both as one of the options in the differential diagnosis of respiratory complaints, and as a comorbid condition which may complicate the treatment of other medical or surgical problems. Furthermore, both the understanding of asthma's pathophysiology, and its optimum treatment methods have undergone radical changes during the past decade.

This three-part discussion reviews our modern understanding of asthma, and proposes diagnosis and treatment guidelines which can assist otolaryngologists in effectively managing their asthmatic patients. Part one summarizes current information on the pathophysiology and increasing prevalence of asthma, its clinical variability, the assessment of asthma sensitivity, and methods for diagnosis of asthma. Parts two and three cover the strategy for asthma management, and the use of both adjunctive and anti-inflammatory therapies for asthma control.