What Is The Contemporary View Of Asthma, And How Does It Differ From Traditional Views?

In the past, asthma was considered a disease principally of airway narrowing, termed  bronchoconstriction. In the traditional view, bronchial passages encircled by specialized muscle fibers became narrowed (constricted), leading in turn to the development of an “asthma attack.” The traditional explanation erroneously emphasized that constriction of the bronchial tubes was the primary, underlying event in asthma. The focus of asthma treatment centered only on reversing the constriction of the breathing passages.

Asthma treatment consequently consisted mostly of relief of airway narrowing once symptoms of cough, chest tightness, breathlessness, and wheeze had become established and recognized. Emphasis was placed on treatment of attack symptoms, rather than on preventive measures. The contemporary perspective on asthma recognizes the importance of bronchoconstriction but assigns it a secondary role. The main “player” or “culprit” in asthma is inflammation. In the modern-day model of asthma, periods of active disease or exacerbation emerge from a back-ground of quiescent periods of remission (Table 5). During an exacerbation, there is increased inflammatory activity in the asthmatic lung. The inflammation, if unchecked, leads to mucous gland stimulation with excess secretions and cough, and to eventual bronchoconstriction or airway narrowing. The increased mucus leads to cough. The bronchoconstriction is responsible for symptoms of breathlessness, wheezing, and chest tightness.

A key feature of asthma is a predisposition to increased lung inflammation. Individuals with asthma develop enhanced inflammatory responses in their lungs, a finding that goes hand in hand with the diagnosis of asthma. They are said to have an innate state of lung baseline hyperreactivity, which sometimes is referred to as “twitchy airways,” a terminology that is strictly speaking incorrect; airways do not twitch! I mention the term as it is (alas) used freely in conversations between physi-cians and their patients in an attempt to describe the distinctive phenomenon of bronchial hyperreactivity. A specialized lung test, called a methacholine challenge (bronchoprovocation) test (described in Question 29), may be helpful to clinicians when evaluating individuals suspected of having asthma and therefore a state of lung hyperreactivity. The tendency to increased base-line hyperreactivity is likely hereditary.

Increased baseline hyperreactivity explains why, for example, the lungs of persons with asthma are more “sensitive” to inhalation of different environmental stimuli such as cold air, strong odors, and cigarette smoke. The presence of bronchial hyperreactivity is of great interest to asthma researchers. It is tempting to speculate about a medication that could modify a person’s bronchial hyperreactivity and so reduce the severity of his or her asthma. The current understanding of asthma as a disease primarily of inflammation, with secondary airway narrowing (bronchoconstriction) as a consequence of an increased inflammatory response, has both research and practical implications . It allows for preventive interventions and for more directed med-ications. Controlling and limiting airway inflammation controls asthma symptoms and leads to normalization of lung function, an excellent prognosis, and a healthy lifestyle. Prompt treatment of an exacerbation always includes anti-inflammatory medication in addition to specific treatment directed to relief of bronchoconstriction.

Recognition of the importance of inflammation in asthma has led to a better understanding of asthma and to the development of more effective treatment. Asthma exacerbations may occur predictably and inevitably following certain exposures, such as the onset of cold winter temperatures, for example. Some individuals “have an attack” every fall at the change of season and must forgo daily routines, including work and school, or avoid leisure activities. Treatment of established symptoms of an “attack” in the traditional view might include a burst of medication, hopefully in the office setting, but possibly in the hospital. The contemporary view of asthma, however, emphasizes a preventive approach. An individual with asthma and a pattern of worsening symptoms at the change of season would benefit from the prescription of stepped-up anti-inflammatory medication as winter approached. By successfully controlling inflammation and keeping a watchful eye out for the emergence of any early signs and symptoms of disease exacerbation, attacks would be avoided, along with significant lifestyle disruptions.

The Contemporary View of Inflammation in Asthma

The modern view of asthma emphasizes the all-important role of inflammation.

Contemporary asthma treatment includes:

  • Avoiding factors that increase lung inflammation
  • Use of medications with anti-inflammatory properties

The traditional perspective erroneously assigned a primary role to air-way narrowing, called bronchoconstriction.

Bronchoconstriction is the consequence of a more powerful stimulus: underlying airway inflammation.

When airway inflammation is present, treating the bronchoconstriction in asthma without treating the accompanying inflammatory response is inadequate treatment.