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Asthma
Management of Chronic Asthma
Christopher John Corrigan
Professor of Asthma, Allergy and Respiratory Science, King’s College London School of Medicine,
Medical Research Council (MRC) Centre for Allergic Mechanisms of Asthma and Guy’s Hospital
Abstract
With modern anti-asthma drugs most but not all asthmatics can be managed sufficiently well so that symptoms have little or no impact on
their lives. This requires a systematic evidence-based use of medications that are usually recommended in guidelines and reflect best
practice but do not necessarily cater for every patient. This article is a summary of the diagnosis and management of asthma according to
current guidelines and an account of why some patients do not respond as anticipated.
Keywords
Asthma, therapy, differential diagnosis, guidelines, treatment failure
Disclosure: Christopher John Corrigan has received various benefits (support for clinical research projects or to attend scientific and clinical meetings) or consultancy and
lecturing fees from the following companies: GlaxoSmithKline, AstraZeneca, Novartis, Allergy Therapeutics, ALK-Abello, Meda Pharma, Amgen and Artu Biologicals.
Received: 27 October 2008 Accepted: 14 May 2009
Correspondence: Christopher John Corrigan, Department of Asthma, Allergy and and Respiratory Science, 5th Floor, Tower Wing, Guy’s Hopsital, Great Maze Pond, London,
chris.corrigan@kcl.ac.uk
Diagnosis of Asthma In adults with suggestive symptoms the diagnosis rests on
Before asthma is treated, it is important to diagnose the illness. demonstrating short-term variability in airway obstruction, preferably
Symptoms are thought to arise from airway inflammation causing by spirometry. In symptomatic patients, abnormal spirometry
obstruction (wheeze, chest tightness, shortness of breath) and hyper- (FEV
1
/forced vital capacity [FVC] ratio <0.7) is strongly suggestive of
reactivity (sensitivity to non-specific stimuli, cough). Any symptom the diagnosis, whereas normal spirometry suggests alternative
may present in isolation. Symptoms are typically worse at night and diagnoses. In patients with airway obstruction, an improvement in
early in the morning and may be exacerbated by colds, exercise FEV
1
of >400ml either acutely after bronchodilator or following a trial
and allergen exposure. Many infants develop wheezing with colds that of therapy strongly suggests the diagnosis. PEF variability measured
frequently remits. Persistent, severe interval symptoms, especially over at least two weeks is another possible approach (the upper limit
developing after two years of age, suggest asthma. A personal or of normal peak flow variability is 20% when expressed as a
family history of atopic diseases supports the diagnosis, although this percentage of the mean), although this procedure has low sensitivity.
is not invariable. Physical signs are typically absent in mild disease. Where patients have near normal spirometry, measurement of
Atypical symptoms and signs suggest an alternative or additional bronchial hyper-reactivity may be helpful; the threshold methacholine
diagnosis (see Table 1). or histamine PC
20
of >8mg/ml includes ≥90% of the non-asthmatic
population, whereas a lower value has 60–100% sensitivity in
Measuring lung function is difficult in children below five years of detecting physician-diagnosed asthma.
age. Diagnosis rests on the history and examination. When asthma
is considered likely, a good symptomatic response to a trial of Pharmacological Therapy
therapy is affirmative, whereas a poor response makes the diagnosis National and global guidelines on asthma management are drawn
unlikely. If the diagnosis is uncertain, a period of watchful waiting or up and revised by panels of specialists, including the British Thoracic
a trial of introduction sometimes followed by the withdrawal of Society (BTS; www.brit-thoracic.org.uk)/Scottish Intercollegiate
therapy may be indicated. Measurement of peak expiratory flow Guidelines Network (SIGN)
1
in the UK, the National Heart, Lung and
(PEF) or forced expiratory volume in one second (FEV
1
) is possible in Blood Institute (NHLBI; www.nhlbi.nih.gov/guidelines/asthma) in the
older children, although serial measurements correlate poorly with US and the Global Initiative for Asthma (www.ginasthma.com)
symptoms and medication needs. Reversibility of ≥12% in baseline worldwide. Although differing in details, all guidelines advocate
PEF or FEV
1
after bronchodilator or a trial of therapy supports the stepwise treatment of asthma matched initially to symptoms, with
diagnosis of asthma, but failure to demonstrate such reversibility later stepping up or down as necessary. While guidelines attempt to
does not exclude it. Tests of airway hyper-responsiveness in children rationalise therapy based on reliable evidence, they cannot cater for
have low sensitivity and generally add little to symptomatic the hopes, fears, aspirations, disease patterns and exacerbating
assessment, although negative responses to methacholine or factors in each individual patient. The following account refers to
exercise challenge make the diagnosis unlikely. the UK guidelines.
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