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Abstract
Background Asthma is one of the commonest childhood diseases. Although cough is considered a key symptom of asthma, little is known about the cough patterns in asthmatic children. Previously, cough patterns in asthma have only been studied subjectively, in terms of frequency and diurnal variation, and it has been reported that asthmatics cough more at night, specifically from midnight until early morning. However, there is little objective data to confirm this. Using an objective cough monitoring system we investigated cough frequency and diurnal patterns of cough over 24 hours in asthmatic children.
Methods Children (age 2–17 years) with a diagnosis of Asthma were asked to wear the VitaloJAK cough monitor for a maximum of 24 hours on two occasions – when symptoms were stable and during an exacerbation. All 24 hour recordings were processed through compression software and coughs counted by listening to the resulting files; the 24 hour cough number were reported.
Results 26 stable asthmatic children (17 male; median age 11.9 years) completed 24 hour recordings when stable; 12 repeated recordings during an exacerbation. During the stable period median total cough counts during awake-hours, sleep-hours and 24 hour periods were 69.5 (range 3–395), 0 (range 0–151) and 71 (range 4–432) respectively. Coughs occurred mostly during the awake time (86%), peaking at 08:00 and 19:00 hours, and rarely occurred during the night when subjects were sleeping (14%). During exacerbations the median total cough counts during awake-hours, sleep-hours and 24 hours were 183 (range 0–632), 18.5 (range 0–128) and 262 (range 10–645), which were significantly higher than during stable recordings (p<0.05). The incidences of day-time cough were similar to that of stable asthmatic recordings (80%) and the incidences of night-time cough remained low (10%). However, during an exacerbation, the peak time of coughing was at 11:00 and 17:00–19:00 hours. The distribution of cough for 12 asthmatic children when stable and during exacerbations is shown in figure 1.
Conclusions Objective monitoring shows that cough frequency in children is greater during the day and was reduced during sleep in both stable and exacerbating asthma. Cough frequency increases during the morning and late afternoon.
Cough frequency distribution during exacerbations and stable asthma for 12 asthmatic children.