Relationship Between Airway Obstruction and Respiratory Symptoms in Adult Asthmatics: Outcome
Figure 1 demonstrates that 17% of our patients had relatively asymptomatic airway obstruction. The long-term outcome of untreated or undertreated asthmatics is not known. We believe, however, that this subgroup of patients should be treated with a level of therapy commensurate with their degree of airway obstruction for the following reasons: the airway obstruction that occurs in asthma is thought to be a manifestation of airway inflammation; airway wall remodeling and fixed airway obstruction are potential complications of chronic airway inflammation, which can be seen even in patients with clinically mild disease; and a number of other well-known asymptomatic conditions such as hypertension, hypercholesterolemia, and hyperglycemia are known to result in irreversible end-organ damage if left untreated.
When first evaluated, self-reported wheezing was the best predictor of airway obstruction in our patients (Figs 2,4). Asthmatics have been shown to more frequently identify wheezing as a characteristic of their exertional breathing difficulty than patients with other forms of cardiorespiratory disease. Persistent wheezing has also been shown to be predictive of airway obstruction in population-based studies of wheezy and asthmatic individuals. Together with these studies, our results suggest that wheezing is the asthma symptom most predictive of the level of airway obstruction. Other common asthma symptoms such as cough and dyspnea may be more reflective of the state of bronchial hyperresponsiveness and lung hyperinflation, respectively.
Spirometry and PEF are frequently used to assess airway caliber in asthma patients. Our data demonstrate that there can be a significant discrepancy between the FEVX and PEF (Fig 5). Laryngeal Abnormalities Calibrated spirometry performed according to ATS guidelines should be considered the “gold standard” for the determination of airflow caliber Submaximal effort during the PEF maneuver, supramaximal flow transients occurring very early during a forced expiration, and PEF maneuver-induced bronchospasm are phenomena that may account for some of the discrepancies between the PEF and FEVX values that we recorded. Thus, in accordance with published asthma guidelines,2 our results suggest that spirometry should be performed during initial encounters with asthma patients and that PEF values should be compared periodically with spirometric indexes of airway caliber.