The Diagnosis of Asthma in Otorhinolaryngology Patients
Amber Luong, MD, PhD,
Asthma is characterized by episodic lower respiratory symptoms (mostly commonly shortness of breath due to wheezing) that result from reversible pulmonary airflow obstruction. Many patients with asthma also suffer from allergic rhinitis and chronic rhinosinusitis (with or without nasal polyps). Severe asthma may be triggered by unrecognized gastroesophageal/laryngopharyngeal reflux. Other conditions with ENT implications may mimic symptoms of asthma, and often diseases commonly evaluated by otorhinolaryngologists (such as rhinitis and rhinosinusitis as well as extraesophageal reflux) may present as co-morbid factors in patients with difficult-to-treat asthma. Obviously, asthma is an important consideration for the patients seeking care from otorhinolaryngologists; however, both patients and their otorhinolaryngologists need to integrate the treatments for both asthma and other co-morbid ENT conditions.
In the asthmatic patient, pulmonary airway inflammation triggers three events that lead to reversible airway narrowing:
- Bronchial smooth muscle contraction leads to rapid bronchoconstriction.
- The inflamed airways demonstrate an exaggerated response to even small stimuli and irritants (the so-called twitch airway).
- Longstanding airway inflammation leads to airway edema and remodeling, furthering narrowing the airway.
The exact causes of asthma are unknown, but asthma researchers are focusing on these themes:
- Dysregulation of the Th1 and Th2 cytokine responses leads to a relative predominance of the Th2 cytokine profile, which has been associated with asthma, allergic rhinitis, and chronic rhinosinusitis.
- Since asthma is a chronic condition, it is presumed to have genetic basis. A complex multi-factorial genetic predisposition probably increases the probability that a specific individual will develop asthma, but those genetic factors alone may not be sufficient.
- Environmental factors, including tobacco smoke and pollution, are presumed to play a role.
For the otorhinolaryngologist, the pathophysiology and the clinical history of asthma both share a significant similarity to both allergic rhinitis and chronic rhinosinusitis.
The diagnosis of asthma requires confirmation of the presence of reversible pulmonary airway obstruction or hyper-responsiveness. The primary clinical symptom and sign is expiratory wheezing, but the absence of wheezing does not exclude the diagnosis of asthma. Other clinical symptoms include cough as well as episodic shortness of breath and/or chest tightness. Such symptoms often worsen during viral respiratory infections, exercise, or exposure to airway allergens and irritants. Chest X-ray is typically normal, except if the patient has another co-morbid condition (such as pneumonia).
Spirometry is required for the firm diagnosis of asthma. According to the Guidelines for the Diagnosis and Management of Asthma, produced by the NHLBI’s National Asthma Education and Prevention Program Expert Panel Report 3, minimal diagnostic criteria are an increase in FEV1 (forced expiratory volume in 1 second) of >200 ml and/or 12% from baseline after inhalation of short-acting beta-agonist (such as albuterol via nebulization). Spirometry, which is both commonly available and easy to perform, must be part of the evaluation of patients with suspected asthma. Furthermore, spirometry is critical for the guiding the long-term treatment of patients with confirmed asthma.
The differential diagnosis for patients with symptoms of asthma is relatively broad, although these other conditions are much less common. Tracheal obstruction may be caused by a tracheal foreign body, tracheal stenosis, and tracheomalacia. Similar condition may also impact the bronchi, too. Vocal cord dysfunction (that is, vocal fold adduction, rather than abduction, during inspiration), a relatively rare condition with a presentation that is very similar to asthma, must also be considered. Laryngopharyngeal reflux (LPR) has been implicated as a cause of a refractory asthma—or it may trigger nonspecific cough that does not have its pathogenesis based upon asthma. Chronic obstructive pulmonary disease (COPD, including chronic bronchitis and emphysema), congestive heart failure, pulmonary embolus, pneumonia all can produce shortness of breath; clinical history is often critical in assessing the likelihood of each of these diagnoses. Primary infiltrative conditions of the lungs may lead to wheezing as well.
Patients who present to otorhinolaryngologists for evaluation and treatment of symptoms of the ears, nose, and throat region often will have previously diagnosed asthma, and other patients with similar presentations will have previously unrecognized asthma. Thus, it is important for otorhinolaryngologists to screen patients for asthma. Often the clinical history alone will determine if more evaluation is warranted. For patients with confirmed asthma, otorhinolaryngologists should assess the relationship between asthma symptoms and co-morbid rhinitis, rhinosinusitis, gastroesophageal/laryngoesophageal reflux, as well as other ENT disorders of the upper and lower airway.
Formal spirometry testing is beyond the scope of practice for many, but not all, otorhinolaryngologists; thus, consultations with pulmonologists and medical allergists, who routinely evaluate and treat patients with asthma, are warranted. Alternatively, patients with an established diagnosis of asthma also will already have one or more physicians who are already treating their asthma. In either scenario, coordination of care is paramount for optimal long-term outcomes.