Dip patterns in asthmatic and non-asthmatic children in Benin-city, Nigeria

Abstract

Objective: Although the calibre of the airway is kept patent by multifactorial control system, there is evidence that the calibre ofthe bronchi varies with time of the day in normal subjects. Asthma isnow known to be a chronic inflammatory disease and this chronic  inflammation causes hyperreactivity and lability in the airway. Therefore,asthma is characterised as a disease where respiratory symptoms arebased on large variation in airway calibre leading to variations in resistanceto airflow over a short period of time.Method: Normal non-asthmatic children leaving within 10km of Universityof Benin Teaching Hospital (UBTH) and whose parents work at UBTH were recruited. These subjects aged 5 – 15 years were initially matched with an index asthmatic case both for sex and age (within six months range). Using a questionnaire the control were screened to exclude any case with history of respiratory, cardiac or any form of active disease or chest deformity or family history of asthma. This was followed by weight and height determination. Both the subject and control were then instructed on the correct use of the mini Wright Peak Flow meter and how to record it inthe diary provided. After five days of measurement, the diaries werecollected and the PEFR were analysed.Results: Two hundred and ten (210) asthmatics and one hundred andeighty healthy children completed the study. The two groups were similar for age, weight and height, but the mean daily PEFR was significantlylower for the asthmatic children (P<0.01). The circadian pattern of distribution of PEFR is similar both in asthmatic and the healthy children, the lowest PEFR was at 6am and maximum was at 2pm and thereafter, there was a gradual fall from the 6pm to 10pm, this was the dominant pattern both in asthmatic and the healthy children. Significant difference in magnitude of PEFR between the two groups occurred at 6am, 6pm and10pm (P<0.01). In all, the asthmatics had lower value. The PEFR ineach case at 2pm was similar; 302.6 l/min for normal children as against3.2 l/min for asthmatic children. Of the asthmatic subject, 205 (97.6%)had a discernable dip pattern compared with 4 (2.2%) in healthy subjects.Conclusion: Dip pattern exists both in asthmatics and non-asthmaticchildren, although, more of the asthmatics had a discernable dip pattern. The airway calibre shows a variation with the time of the day, both in asthmatics and normal subjects with lowest values in the morning and highest in the afternoon. But at each time of the day, the asthmatics had lower PEFR values than normal children. This maybe relevant in the management and follow-up of the asthmatics .