Original article

A. ZEBROWSKA, A. ZWIERZCHOWSKA


SPIROMETRIC VALUES AND AEROBIC EFFICENCY OF CHILDREN
AND ADOLESCENTS WITH HEARING LOSS



Department of Physiology, Academy of Physical Education, Katowice, Poland


  Vital capacity (VC), forced expiratory volume in 1 s (FEV1), peak expiratory flow (PEF), mean forced expiratory flow (FEV25-75), and maximum voluntary volume (MVV) were measured in 36 girls and 36 boys with hearing loss and compared with the same number of normal healthy children, all subjects were aged 10-16 years. They participated in an exercise test to calculate VO2 max in order to determine their physical efficiency. We found that all spirometric indices tended to be lower in deaf children, in all age-groups studied and irrespective of gender, compared with their hearing counterparts; the differences assumed significance with respect to PEF and MVV (P<0.05). Moreover, some deaf children had an appreciably lower level of VO2max compared with hearing children. Our results demonstrate that sensory deprivation of deaf children affects functional capabilities of the respiratory system.

Key words: children, hearing loss, maximum oxygen uptake, spirometry



INTRODUCTION

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 subjectsĺ 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, Krakˇw, and Racibˇrz 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 (FEV1), peak expiratory flow (PEF), mean forced expiratory flow (FEV25-75), maximal flow volume curve (MEF75, MEF50, MEF25), 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 VO2max 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 VO2max 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 FEV1 (r=0.59, P<0.001), MVV (r=0.62, P<0.001), and VO2max (r=0.45, P<0.010), on the other side, were observed. There also were positive correlations between FEV1 and MVV (r=0.38, P<0.01) and FEV1 and VO2max (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 FEV1, 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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Authorĺs address: A. Zebrowska, Department of Physiology, Academy of Physical Education, Miko│owska 72A St., 40-065 Katowice, Poland; phone: 608 418581.
e-mail: olazebrowska@yahoo.com