Motor abilities and sport performance of children increase with age primarily because of the development of the neuromuscular and cardiorespiratory systems (1, 2, 3). Sensory impairment in children with hearing loss is associated with disturbance of the balance and coordination abilities, which in some cases may even lead to decreased muscle strength and respiratory function (4, 5, 6). Small changes in airway pressure due to lack of verbal communication might also influence spirometric values of deaf children (7, 8). Studies have demonstrated that rehabilitation of vocal folds, voice, and speech depends on increased forced expiratory volume (8, 9). However, during childhood several other factors (age, gender, stature, and environmental factors) may modify the lung development and respiratory function (8, 10). There appears an age-dependent relationship between body size and the values of spirometric indices (10). Thus, it is a reasonable assumption that the posture may have a direct influence on lung volume, whereas factors that determine the airway geometry affect airflow variables (11). The present study was carried out to estimate the values of spirometric variables in deaf children and deaf adolescents and compare them with those in their hearing counterparts.
MATERIAL AND METHODS
A group of 72 children with hearing loss and 72 healthy children with normal hearing (control group) participated in the study. All subjects’ parents granted their written permission and the experiment was approved by Ethics Committee of the Academy of Physical Education in Katowice, Poland.
Both deaf (D) and hearing (H) subjects were divided into 3 age groups ranging
10-11, 12-13, and 16-17 years. All subjects presented a normal intellectual
level with no chronic disorders or other respiratory problems during the preceding
2 wk. All of them were recruited from students attending special schools for
deaf children in the cities of Katowice, Kraków, and Racibórz in Poland. Medical
history and information about the etiology deafness were prepared by the school
personnel. All deaf children were characterized by loss of hearing above 80
dB. In the group, 46% of children had acquired hearing loss (e.g., from meningitis
before the age of 2 yr), 22% had heredity hearing loss, 16% had congenital,
and in 16% the cause of deafness was unknown. Age, height, body mass, and maximal
oxygen uptake of the subjects are presented in
Table 1 and
Table 2.
Table 1.
Characteristics of the girls investigated. |
|
Values are
means ±SD. D - deaf children, H - hearing children, VO2max
- maximum oxygen uptake. *Significant differences in D vs. H at
P<0.05. |
Table 2.
Characteristics of the boys investigated. |
|
Values are
means ±SD. D - deaf children, H - hearing children, VO2max
- maximal oxygen uptake. *Significant differences in D vs. H at
P<0.05. |
The experimental procedures were explained to each deaf child by both sign language
and in writing. Standard spirometry (PonyGraphic 3.7, Cosmed, Italy) was used
to analyze: vital capacity (VC), forced expiratory volume in 1 s (FEV
1),
peak expiratory flow (PEF), mean forced expiratory flow (FEV
25-75),
maximal flow volume curve (MEF
75, MEF
50,
MEF
25), and maximal voluntary volume in 10 s
(MVV). The measurements were carried out one after another always in the morning.
For the determination of physical efficiency, Astrand -Ryhming test was performed
on a cycle ergometer (Monark, Sweden) (12, 13). The exercise consisted of 5
min cycling period. Both spirometry and exercise tests were performed at school.
Data are presented as means ±SD. All data were tested for normal distribution
and were analyzed by one-way of ANOVA. Significant differences for spirometry
and maximal oxygen uptake values between the deaf and hearing children in each
age group were determined using Students-t test. The relationships among FVC
and MVV, and VO
2max were checked with Pearson
correlation coefficient regression analysis in each group investigated. Statistical
significances was set at P<0.05.
RESULTS
We found an age-dependent significant increase in VO
2max
in both deaf and hearing children (F=3.93, P<0.05). This increase in deaf children,
in some cases, lagged behind that present in hearing children (
Table 1
and
Table 2). Furthermore, we found a significant influence of deafness
on PEF (F=5.83, P<0.02) and MVV (F=9.3, P<0.01), but no effect was seen with
respect to VC. The deaf girls, across all age groups studied, had significant
lower values of PEF (P<0.05) and MVV (P<0.01) compared with the hearing girls
(
Table 3). Similar differences, with the exception of PEF in the youngest
10-11 years old, also were noted in boys (
Table 4). VC showed a tendency
to decrease in either sex and at all ages, but the decrease failed to assume
statistical significance.
Table 3.
Spirometric values of the girls investigated. |
|
Values are
means ±SD. D - deaf children, H - hearing children. *Significant differences
in D vs. H at P<0.05 and ** at P<0.01. The number of girls in each
group - as in Table 1. |
Table 4.
Spirometry values of investigated boys. |
|
Values are
means ±SD. D - deaf children, H - hearing children. *Significant differences
in D vs. H at P<0.05 and ** at P<0.1. The number of boys in each
group - as in Table 2. |
Significant positive correlations between VC, on the one side, and FEV
1
(r=0.59, P<0.001), MVV (r=0.62, P<0.001), and VO
2max
(r=0.45, P<0.010), on the other side, were observed. There also were positive
correlations between FEV
1 and MVV (r=0.38, P<0.01)
and FEV
1 and VO
2max
(r=0.43, P<0.01).
DISCUSSION
Our study reveals that children with hearing loss showed disadvantageous changes
in spirometry, pointing to the possibility of delayed functional development
of the lungs compared with normal, hearing counterparts. Physical efficiency
of deaf children, as assessed from the maximum oxygen uptake, also was. Our
observations are in agreement with other studies that described lower aerobic
and cardiorespiratory efficiency in deaf children (5, 6). Jonsson and Gustafsson
(9) found that physically active children with normal hearing have lung function
values above the median values due to a better understanding of spirometry instructions.
In the present study, the experimental procedures were shown to children with
hearing loss by sign language and in writing. These children were instructed
and encouraged to participate in the spirometry test. Decreased values of spirometric
indices observed in the present study in children with hearing loss might also
be explained by lack of the development of a verbal language in these children,
so that the positive effect on lung development through the use of the lung
for speech, singing, or screaming is missing. Consequently, physiological factors
that depend on respiratory adaptation have a negative influence on the response
to physical exercise in deaf children (14). However, physiotherapy of breathing,
as an important part of voice therapy and rehabilitation, may modify respiratory
function in these children. Spirometric values obtained in deaf children of
this study were referenced to the predicted values in normal children (11, 15).
We found significant decreases in FEV
1, PEF,
and MVV values in deaf children (
Table 3 and
Table 4), and a meager
12% and 8% decrease in VC in deaf boys and girls, respectively.
In conclusion, our data demonstrate that sensory deprivation of deaf children aged 10 to 16 years affects functional capabilities of the respiratory system. Therefore, it is necessary to encourage deaf children to participate in auditory rehabilitation programs and systematic physical exercises.
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