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

Abstract

Abstract Objective: Although the
calibre of the airway is kept patent
by multifactorial control system,
there is evidence that the calibre of
the bronchi varies with time of the
day in normal subjects. Asthma is
now 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 are
based on large variation in airway
calibre leading to variations in resistance to airflow over a short period
of time.
Method: Normal non-asthmatic children leaving within 10km of University of 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 in
the diary provided. After five days
of measurement, the diaries were
collected and the PEFR were anwere
collected and the PEFR were analysed.
Results: Two hundred and ten (210)
asthmatics and one hundred and
eighty healthy children completed
the study. The two groups were similar for age, weight and height,
but the mean daily PEFR was significantly lower 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 and
10pm (P<0.01). In all, the asthmatics had lower value. The PEFR in
each case at 2pm was similar; 302.6
l/min for normal children as against
3.2 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-asthmatic
children, 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.
Key words: Asthma, dip pattern,
circadian rhythm, Peak expiratory
flow rate.