Rhinitis and Asthma: "Combined Allergic Rhinitis and Asthma Syndrome"
The increasing recognition over the last 50 years that allergic rhinitis and allergic asthma frequently co-exist, has led to the concept that these seemingly separate disorders are possibly the same disease, with symptoms occurring to a greater or lesser extent in the upper airways (rhinitis) or lower airways (asthma). When patients with either allergic rhinitis or allergic asthma are thoroughly investigated, it is frequently found that they have allergic inflammation and airway sensitivity throughout all of the airways.
Non-allergic diseases of the nose, such as common colds or sinusitis, can often lead to the development or worsening of asthma symptoms, particularly in children. Even in patients with non-allergic, persistent (perennial) rhinitis, there is an increased risk that asthma will develop.
Although the upper airway and lungs have many physical similarities, there are also some important differences. The upper airway and sinuses have a large blood supply, and vasodilation causes much of the nasal blockage experienced in allergic rhinitis. The lungs are lined with smooth muscles that constrict and become narrowed, causing tightness in the chest, wheezing, difficulty with breathing, and cough.
Concurrent upper (rhinitis) and lower (asthma) respiratory tract symptoms.
There have been a number of research studies investigating the link between rhinitis and asthma, leading to the following information:
In one study of 99 patients who were followed up to ten years after they were first diagnosed as having allergic rhinitis, allergic asthma, or both:
32% of rhinitis patients developed asthma;
50% of patients with asthma alone developed rhinitis.
A number of studies have shown that:
70-90% of patients with asthma also have rhinitis;
40-50% of patients with allergic rhinitis also have asthma.
Sinusitis has been shown in different studies to occur in up to:
25-70% of adults with asthma;
20-60% of children with asthma;
50% of patients allergic to inhaled allergens, e.g., pollen, house dust mites.
Heightened sensitivity of the airways (airways hyperreactivity) has been demonstrated in:
15-65% of patients with allergic rhinitis.
Viral infections of the nose
Common colds and other viral infections of the nose are frequently associated with worsening of asthma. People who already have allergic disease are at high risk to develop asthma following a viral respiratory tract infection.
The upper airway acts as a physical filter, resonator, heat exchanger and humidifier, so that air that is breathed in through the nose arrives into the lungs at a temperature of approximately 37 degrees C and almost 100% saturated. Inhaled particles greater than 5-6 microns are usually retained in the upper airway.
The upper airway and the lungs show the same immunologic response to allergens, and this immune response usually results in inflammation of both the upper and lower airways. Even when an allergic individual is symptom free, there is still some persistent inflammation in the airways.
Current research is examining the reasons why some people develop allergic rhinitis and some people develop allergic asthma. It is thought that this might be the result from different amounts of IgE antibody being produced, or being present, in the upper airway and lungs.
The development of either upper or lower airway symptoms can depend on the particular allergen to which the sensitized individual is exposed. Seasonal allergens, for example grass or tree pollens, can cause intermittent symptoms e.g., hay fever and allergic conjunctivitis. These are caused by the larger allergen particles – approximately 5 microns in size - which become lodged in the nose and eye. Allergens which are present year-round, e.g., animal allergens and house dust mites, are more likely to cause persistent symptoms of rhinitis and/or asthma. These tend to be the smaller allergen particles measuring less than 1 micron, which are easily inhaled into the lungs.
Because it is likely that patients with either allergic rhinitis or asthma will have generally sensitive airways, allergy experts recommend that all patients with allergic rhinitis and/or sinusitis who are seeing a doctor, should be tested to see if there is also evidence of underlying asthma. Patients who have asthma should tell their doctor about intermittent or persistent nasal symptoms.
Because of the structural differences in the upper airway and lung, some of the medications used to treat the symptoms of upper and lower airways disease are different. Nasal blockage caused by swelling can be treated with medications called alpha-adrenergic agonists that act as vasoconstrictors or decongestants.
The constriction of the smooth muscle in the lungs which leads to the symptoms of asthma is treated with similar medications called beta2 agonists which act as bronchodilators to relax the constricted muscles.
Treatment for Combined Allergic Rhinitis and Asthma Syndrome is directed at the underlying inflammation that occurs in rhinitis and asthma.
Effect of nasal treatment on asthma
Locally applied (topical) corticosteroid sprays given to improve rhinitis symptoms can also improve symptoms of asthma and reduce the underlying hyperreactivity (the heightened sensitivity of the lungs to inhaled stimuli).
Antihistamines, in the doses prescribed for seasonal allergic rhinitis, may also improve concurrent mild seasonal asthma symptoms. Administration of an antihistamine plus pseudoephedrine has been shown to improve asthma symptoms and reduce the amount of medication needed in patients with seasonal allergic rhinitis and mild asthma. A similar benefit has been demonstrated with antihistamines used in association with antileukotrienes.
In children, asthma flare-ups in relation to viral infection can be controlled by continuous antihistamine treatment. In the ETAC (Early Treatment of the Atopic Child) study, it was shown that an early and continuous antihistamine treatment could reduce the onset of asthma in allergic children.
Antibiotic therapy for sinus infections in children has been shown to improve asthma. Improvement in asthma has been shown after sinus surgery in patients with either nasal polyps, or rhinosinusitis, and asthma.
Treatment of rhinitis and asthma together
Topical corticosteroids can be given for both rhinitis and asthma at the same time.
A new class of anti-allergy drugs, anti-IgE antibodies, are injected and can improve both nasal and bronchial airway symptoms.
Allergen immunotherapy (allergy vaccination) is an important therapeutic tool for the management of Combined Allergic Rhinitis and Asthma Syndrome and it is helpful for patients with co-existing asthma and rhinitis. Immunotherapy can modify the natural history of the disease and maintains its effects for years after discontinuation. Sublingual-Swallow immunotherapy seems to be particularly suitable for child patients because it can be given orally.
Uncontrolled allergic rhinitis can lead to worsening of co-existing asthma.
Prompt and effective treatment of nasal disease can have a marked effect on preventing the development of asthma, and on existing asthma symptoms.
Airway: Upper airway – the nose and sinuses; Lower airway - the lungs
Airway hyperreactivity: Extreme sensitivity of the airways to inhaled stimuli, eg, cold air, allergen particles, pollutants
Allergen: A substance, usually a protein, found particularly in plants, insects (especially mites and stinging insects), foods, pets and molds, which is normally harmless but in susceptible individuals can induce the development of the allergy antibody (IgE) and lead to allergic reactions.
Asthma: A disease caused by inflammation of the airways of the lung, which leads to symptoms of coughing, breathlessness, tightness in the chest, and wheezing
Bronchodilators: drugs which relax the tightened (constricted) muscles or the lungs
Epidemiology: the study of which group or groups of people experience a disease, and the possible causes of the disease within that group
IgE antibody: the "allergy" antibody of the blood, which reacts with a specific allergen
Nasal polyps: Benign grape-like growths of the lining of the nose
Rhinitis: A disease caused by inflammation of the airways of the nose, which leads to symptoms of sneezing, itching, runny nose, and nasal blockage
Sinusitis: A disease caused by infection of the sinuses (air spaces) in the face, located above the eyes and behind the cheek bones
Vasoconstrictors: drugs that reduce swelling of blood vessels
Viral infection: Infection caused by a virus, e.g., the common cold