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Techniques of assessing small airways dysfunction.

McNulty W, Usmani OS - Eur Clin Respir J (2014)

Bottom Line: Traditional lung function tests may only become abnormal once there is a significant burden of disease within them.These tests are now moving from the realms of clinical research laboratories into routine clinical practice and are increasingly useful in the diagnosis and monitoring of respiratory diseases.This article gives an overview of small airways physiology and some of the routine and more advanced tests of airway function.

View Article: PubMed Central - PubMed

Affiliation: National Heart and lung Institute, Imperial College London and Royal Brompton Hospital, London, UK.

ABSTRACT
The small airways are defined as those less than 2 mm in diameter. They are a major site of pathology in many lung diseases, not least chronic obstructive pulmonary disease (COPD) and asthma. The small airways are frequently involved early in the course of these diseases, with significant pathology demonstrable often before the onset of symptoms or changes in spirometry and imaging. Despite their importance, they have proven relatively difficult to study. This is in part due to their relative inaccessibility to biopsy and their small size which makes their imaging difficult. Traditional lung function tests may only become abnormal once there is a significant burden of disease within them. This has led to the term 'the quiet zone' of the lung. In recent years, more specialised tests have been developed which may detect these changes earlier, perhaps offering the possibility of earlier diagnosis and intervention. These tests are now moving from the realms of clinical research laboratories into routine clinical practice and are increasingly useful in the diagnosis and monitoring of respiratory diseases. This article gives an overview of small airways physiology and some of the routine and more advanced tests of airway function.

No MeSH data available.


Related in: MedlinePlus

(a) Multiple breath nitrogen washout curve with individual breaths demonstrating Phase III slope (SnIII) from 1st (b) and 10th (c) breaths.
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Figure 0002: (a) Multiple breath nitrogen washout curve with individual breaths demonstrating Phase III slope (SnIII) from 1st (b) and 10th (c) breaths.

Mentions: The MBNW is a modification of the single breath technique. The patient inhales 100% O2 from FRC with a fixed tidal volume and respiratory rate to wash out the resident nitrogen from the lungs. The test continues until the exhaled nitrogen is less than 1/40th of the original concentration (approximately 2%) for three successive breaths. The speed and efficiency of gas mixing is determined by tidal volume, breath frequency, and ventilation heterogeneity. Thus, by keeping breath frequency and tidal volume relatively constant, inferences about ventilation heterogeneity can be made (90). Figure 2 demonstrates the nitrogen washout curves from a MBNW test.


Techniques of assessing small airways dysfunction.

McNulty W, Usmani OS - Eur Clin Respir J (2014)

(a) Multiple breath nitrogen washout curve with individual breaths demonstrating Phase III slope (SnIII) from 1st (b) and 10th (c) breaths.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4629724&req=5

Figure 0002: (a) Multiple breath nitrogen washout curve with individual breaths demonstrating Phase III slope (SnIII) from 1st (b) and 10th (c) breaths.
Mentions: The MBNW is a modification of the single breath technique. The patient inhales 100% O2 from FRC with a fixed tidal volume and respiratory rate to wash out the resident nitrogen from the lungs. The test continues until the exhaled nitrogen is less than 1/40th of the original concentration (approximately 2%) for three successive breaths. The speed and efficiency of gas mixing is determined by tidal volume, breath frequency, and ventilation heterogeneity. Thus, by keeping breath frequency and tidal volume relatively constant, inferences about ventilation heterogeneity can be made (90). Figure 2 demonstrates the nitrogen washout curves from a MBNW test.

Bottom Line: Traditional lung function tests may only become abnormal once there is a significant burden of disease within them.These tests are now moving from the realms of clinical research laboratories into routine clinical practice and are increasingly useful in the diagnosis and monitoring of respiratory diseases.This article gives an overview of small airways physiology and some of the routine and more advanced tests of airway function.

View Article: PubMed Central - PubMed

Affiliation: National Heart and lung Institute, Imperial College London and Royal Brompton Hospital, London, UK.

ABSTRACT
The small airways are defined as those less than 2 mm in diameter. They are a major site of pathology in many lung diseases, not least chronic obstructive pulmonary disease (COPD) and asthma. The small airways are frequently involved early in the course of these diseases, with significant pathology demonstrable often before the onset of symptoms or changes in spirometry and imaging. Despite their importance, they have proven relatively difficult to study. This is in part due to their relative inaccessibility to biopsy and their small size which makes their imaging difficult. Traditional lung function tests may only become abnormal once there is a significant burden of disease within them. This has led to the term 'the quiet zone' of the lung. In recent years, more specialised tests have been developed which may detect these changes earlier, perhaps offering the possibility of earlier diagnosis and intervention. These tests are now moving from the realms of clinical research laboratories into routine clinical practice and are increasingly useful in the diagnosis and monitoring of respiratory diseases. This article gives an overview of small airways physiology and some of the routine and more advanced tests of airway function.

No MeSH data available.


Related in: MedlinePlus