Nocturnal Wheeze Measurement in Young Asthmatics

Abstract

Nocturnal exacerbation is one of the criteria for defining asthma severity. The aim of this study was to look at the relationship between subjective complaints of nocturnal asthma symptoms, objectively recorded wheezing, and spirometry values. Continuous overnight recording and analysis of respiratory sounds were performed in the homes of 12 young asthmatic patients (7 male), aged 7–18 years, who reported symptoms when seen in clinic. Patients kept an asthma symptom diary for 1 week. They had spirometry the evening before and the morning after the nighttime study. Wheezing was identified and quantified by an FFT-based computer algorithm. Seven patients reported nocturnal asthma symptoms the next morning. Three patients had sustained wheezing episodes lasting 21, 25, and 36 minutes, respectively. They all had a morning FEV₁ ≤ 51% predicted, whereas none of the 10 without wheezing had a morning FEV₁ ≤ 51% predicted. Two of them reported nocturnal asthma and one did not. There was a significant relationship between night-time wheezing and lower FEV₁ the next morning by both parametric (unpaired t-test, p = 0.004) and nonparametric (Mann-Whitney, p = 0.009) tests, and between night-time wheezing and larger diurnal variation in FEV₁ (p = 0.038, p = 0.036, respectively). There was no significant relationship between subjective complaints of nocturnal asthma and objective measurement of wheezing or the FEV₁ the evening before the nocturnal study. Night-time wheeze was associated with a morning FEV₁ ≤ 51% predicted and more pronounced diurnal variation of FEV₁. Recalled nocturnal symptoms may not necessarily reflect wheezing and may reflect chest tightness or other sensations. Computerized acoustic monitoring provides objective evaluation of night-time wheezing.