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Healthcare Professionals

Introduction to BronkoTest

The BronkoTest sputum colour test is used to characterise a COPD patient’s normal chest-related symptoms and the changes that occur during an exacerbation.  It documents the 3 key symptoms of such episodes, namely increased breathlessness, new sputum production or increased volume, and the purulent nature of the sputum.  These help determine the need for and response to antibiotic therapy.

The Bronko Test COPD Monitoring Pack has been produced for patients at the request of healthcare professionals and facilitates communication and understanding of episodes and reasons for different treatments between the healthcare professional and the patient.

Exacerbations of COPD are a major cause of morbidity and mortality.  Frequent episodes are associated with worse health status (Ref. 1) and a greater deterioration in lung function (Refs. 2,3).

The reasons for the deterioration in lung function are not certain but probably relate to inflammation.  Exacerbations can be associated with inflammation and an accumulation of neutrophils in the sputum,although not in every case (Ref. 4).  It is important to note that neutrophils contain proteolytic enzymes that have the ability to produce all the pathological features of COPD including emphysema (Ref. 5), mucous gland hyperplasia (Ref. 6), mucous hyper secretion (Ref. 7) and damage to the mucociliary escalator which is a critical feature of the lungs host defence (Ref. 8).  Thus, it would seem logical that exacerbations that are associated with neutrophil influx would be the episodes most likely to result in progressive deterioration in COPD.

The Neutrophils
The neutrophil is the key component of the secondary defence system of the lung.  During bacterial exacerbations new, or an increased number, of bacteria are found in secretions (Ref. 9) and this is associated with the production of a key neutrophil chemoattractant (LTB4) necessary to drive neutrophil influx (Refs. 10 and 11).  The release of LTB4 is very dependent upon the bacterial load (Ref. 12) which probably explains why patients with COPD are often “colonised” by bacteria but remain well.  As bacterial numbers rise (>10 (Ref.6) colony forming units/ml) the neutrophils numbers in the lung also rise (changing the colour) and release the damaging enzyme neutrophil elastase (Fig. 1).  Prompt and appropriate treatment for these episodes is required but management including antibiotic therapy depends on recognising the nature of the episodes.

Antibiotics
There is a general consensus that antibiotic therapy is effective in exacerbations of COPD.  However, emerging microbial resistance urges caution and expedient use of such therapy.

In the best controlled study of antibiotic therapy (considered the gold standard) Anthonisen and his colleagues graded the episodes based on symptoms (Ref. 13).

An exacerbation of COPD is a “sustained episode in which the patient’s symptoms exceed the normal daily variability and requires a new intervention” (Ref. 14).  The key symptoms are:

1.  Increased breathlessness
2.  New or increased sputum volume
3.  Increased sputum purulence

The Anthonisen study overall confirmed that antibiotics were beneficial but the clearest effect was seen if al 3 of these symptoms were present.  Of these 3, the key is sputum purulence.

Sputum Purulence
Purulent sputum reflects neutrophil influx into the secretions.  This is because the neutrophils contain myeloperidoxidase (a green protein unique to this cell).  Thus purulence of sputum can be used as a guide.  It not only relfect the likelihood of identifying bacteria (Fig 2) but also the bacterial load (Ref. 4), the inflammation (Ref. 15) and damaging potential of the secretions (its proteolytic enzyme content). (Fig 1)

Using this as a marker it was possible to withhold antibiotic therapy in patients with exacerbations of COPD if the sputum was mucoid and remained so throughout the episode as it resolved (Ref. 4).  On the other hand those with purulent sputum showed resolution of the sputum colour and their other symptoms over 5-7 days (Ref. 16).  Thus simply observation of sputum colour can help determine the need for antibiotic therapy in acute exacerbations of COPD if pneumonia is not suspected as well as monitoring the response to therapy.  Furthermore, patients find it easy to use and follow.

Summary:

o BronkoTest is a monitoring tool that enables patients and their physicians to manage COPD more efficiently
o Sputum colour is a central feature of an agreed patient self-care strategy
o Sputum colour is based on a scientific understanding of the interaction of bacteria and host defences in the airways
o Sputum colour indicates the need for antibiotic therapy in patients with COPD who have an exacerbation of their airways disease







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