Objectives: To test symptom perception in asthma under natural circumstance
s and to establish relationships between changes in airway obstruction as i
ndicated by wheeze, dyspnea, general sensations, and emotional state.
Design: Continuous in vivo monitoring.
Method: Symptom perception was tested in 30 adolescents with severe, unstab
le asthma. They were continuously monitored in their homes for 72 h. Sympto
m perception was defined as the relation between self-reported dyspnea and
airway obstruction as evident from audible wheeze. Tracheal sounds were con
tinuously recorded with wireless telemetry for wheeze assessment. Dyspnea w
as assessed four times per day on a Likert-type 10-point scale, as well as
four times randomly after pager remote command. The subjects kept records o
f use of medication, daily activities, general symptoms, and mood state in
a diary.
Results: There were nine subjects with one or two wheeze episodes, another
three subjects with three or four episodes, and one subject with almost con
tinuous wheeze. The presence of wheeze in general related significantly to
a rise (from individual baseline) in dyspnea of > 2.5 scale points. Acute w
heeze was the best predictor of a rise in dyspnea, but prolonged wheeze cor
related significantly with negative mood and general symptoms.
Conclusion: Patients with prolonged airway obstruction perceived symptoms l
ess well and were more vulnerable to negative effects of asthma than patien
ts with acute onset airway obstruction.