1
34
Methods
Physical Examinationns and Measurements: Before
the commencement of the study, two research assistants
who were junior resident doctors in the same department
with the researcher were trained in the art of the
examination according to specified methodology. One
research assistant was trained in the art of physical ex-
amination and apex beat location and for every ten chil-
dren the researcher examined, the research assistant ex-
amined one child to minimize observer error. The other
research assistant assisted in anthropometric measure-
ments and for every ten children the researcher exam-
ined, this assistant also examined one to minimize ob-
server error.
This was a cross sectional study carried out on appar-
ently healthy Nigerian children between December 2009
and April, 2010. The study was conducted in Sagamu,
Ogun State; a town located within the Yoruba cultural
region of the southwestern Nigeria. Institutional ethical
approval was obtained from the Scientific and Ethical
Review Committee of the Olabisi Onabanjo University
Teaching Hospital, Sagamu and informed consent was
also obtained from the parents and guardians of selected
children.
2
Sample size: A previous study reported the mean apex
beat distances from the midline in different age groups
of children from birth to ten years. Assuming a margin
of error of 5% of the mean for each age group, the sam-
ple that would be necessary to study at 5% level of sig-
nificance (95%4 confidence inte2rval) was calculated from
For each subject, the location of the apex beat was 5deter-
mined according to standard clinical methods. The
apex beat was determined in the supine position in the
newborn babies and infants, in erect position in children
aged between one and three years, and in both erect and
2
2
2
the formula: N = (࣌ [ Zߙ/2] ) / ε where ࣌ is the as-
sumed standard deviation, Zα/2 represents Type -1 Error
while ε is the margin of error (5% for each age group).
The total calculated sample size was 237 (Table 1).
supine positions in the others. The location of the apex
beat was measured from the midline, nipple line and the
mid-clavicular line. The midline was established by
joining the central point in the suprasternal fossa to the
xiphisternal angle, and the horizontal distance of the
apex beat and the nipple were measured from the mid-
line using an inelastic tape. The extreme medial and
lateral ends of the clavicle were identified and the corre-
sponding points on the skin marked with ink. The length
of the clavicle represented by these points marked on the
skin was similarly measured. Half of the clavicular
length was taken as corresponding to the mid clavicular
line. Horizontal distance of the mid clavicular line was
measured from the midline.
Table 1: Sample size calculation for each age group using
mean distance of apex beat from the midline
Age Group
࣌
ߝ
Mean
Z
ߙ/2
Sample size
Neonates
1 yr
1yr-≤ 2yrs
2yrs-≤ 3yrs
3yrs-≤4yrs
4yrs-≤ 5yrs
5yrs-≤ 6yrs
6yrs-≤7yrs
7yrs-≤ 8yrs
8yrs-≤9yrs
9yrs-≤10yrs
Total
2
3
4
4
4
5
5
5
5
5
5
.8
.8
.1
.7
.6
.0
.1
.2
.4
.5
.7
0.4
0.4
0.7
0.3
0.4
0.8
0.5
0.7
0.6
0.5
0.6
1.96
1.96
1.96
1.96
1.96
1.96
1.96
1.96
1.96
1.96
1.96
0.19
0.14
0.21
0.24
0.23
0.25
0.26
0.26
0.27
0.28
0.29
17
31
43
06
12
39
14
28
19
12
16
≤
˃
˃
˃
˃
˃
In subjects below two years o®f age, the weight was
measured using the KinLee electronic bassinette
weighing scale with accuracy of 0.01kg with the sub-
jects naked while in subjects above two years of age, the
˃
˃
˃
˃
®
weight was measured with the Globe electronic weigh-
237
ing scale with accuracy of 0.1kg, with the subject stand-
ing upright and bare footed on the scale and with only
pants on.
Sampling method: The neonates and infants were re-
cruited from the maternity unit and Immunization Clinic
of the Olabisi Onabanjo University Teaching Hospital,
Sagamu. Children aged between one and five years were
recruited from day care centres and nursery schools
while children aged between 6 and 10 years were re-
cruited from primary schools in Sagamu, all of which
were randomly selected.
Heights were measured in subjects above two years of
age using a stadiometer, with the c-h8ild standing erect
6
and bare footed on the stadiometer. In subjects below
two years of age, the recumbent length was measured
using an infantometer. Both equipment were calibrated
in centimetres and millimetres.
The inclusion criterion was age from birth to 10 years.
The newborn babies included were term, products of
spontaneous vertex delivery, appropriate for gestational
age from 12 hours of age without asphyxia or other
forms of critical illness. Physical examinations of sub-
jects were done to exclude cardiac pathology and
chronic illnesses. Subjects with displaced trachea, car-
diac murmurs, cyanosis or features of chronic debilitat-
ing conditions were excluded. Those who satisfied the
inclusion criteria were recruited consecutively until the
sample size was reached.
There are two landmarks which can be used for the
measurement of chest circumference. It can be measured
9
at the level of the nipple and at the level of the xiphis-
1
0
ternal junction . However, because the level of the nip-
1
0
ple may vary among individuals , therefore, the chest
circumference was measured in this study at the level of
the Xiphisternal junction, using an inelastic measuring
tape calibrated in centimeters and millimeters.
From the measured values of weight and 11height, the
body mass index were calculated as follows:
2
BMI = Weight (Kg)/ Height (m)
The body surface area was obtained using the