DISCUSSION
Current study investigated the role of spirometry and LCI in evaluation
of long-term lung function in children with CLM after surgical
intervention and revealed that children who underwent surgery for CLM
have impairment in lung functions compared to healthy children.
Lung growth and development continues in childhood after
birth15,16. Also lungs compansate the tissue loss by
compensatory growth and remodeling which may result in improvement of
clinical condition and respiratory functions after surgical
intervention. Most reports showing normal lung functions with spirometry
after surgery in the follow-up of CLM patients may suggest this
mechanism11,12.
In our study, mean spirometric values were within normal range in
patients with CLM. Similarly, normal spirometric results was reported by
Keijer et al. in 14 post-operative CLM children11.
Also Beres et al. showed that CLM patients mostly have normal
spirometric results in the post-operative period12.
Even though, lung function test parameters in spirometry were in normal
range in both study groups, patients with CLM had significantly lower
values than healthy control group. It may be speculated that, CLM
patients may have a mild deterioration in lung function in the
post-operative period.
Compensatory growth and remodeling after surgical resection of
congenital abnormality may cause inhomogeneity in ventilation
distribution. In such circumstances, LCI may be more accurate to detect
early peripheric airway deterioration compared to spirometry. Therefore,
LCI was used in addition to spirometry in this study and statistically
significant differences were detected between the two groups. LCI
assessment results, in long term follow-up, demonstrate that, impairment
and incomplete recovery in peripheric small airways occur in CLM
patients after surgery.
As mentioned before, LCI is more accurate and sensitive for early
detection of lung diseases and evaluating lung
function17-19. In a study conducted by 43 children
with cystic fibrosis (CF) and 28 healthy controls, 23% of CF patients
had reduced FEV1 and in contrast LCI was found to be
abnormal in %63 of them20.
In the current study, although 11 patients out of 15 had abnormal LCI
values, only 4 of them had lower spirometric results. So, LCI
measurement enable to detect lung function impairement in 7 patients
which had normal spirometric results. Also a strong inverse correlation
between LCI and spirometry found in our study suggests the usage of LCI
in the long-term follow-up of CLM patients
To our knowledge, there is only one previous study comparing LCI with
spirometry for the assessment of lung function in post- operative.
Mandaliya et al. found abnormal FEV1% and LCI values in
CLM patients post-operatively compared to healthy controls similiar to
our study21. In both studies, although
FEV1 values were reported to be lower than the controls,
they were over the 80% predicted which is accepted to be the cut-off
point for normality. Mandaliya et al. reported lower BMI and height
values which may result in a decrease in spirometry and LCI
measurements21. In contrast to this study, BMI and
height of all our patients were in normal range.
In the current study, LCI values of the healthy controls were higher
than the previous studies. one of these studies, using the same
technique, mean LCI value was found to be as 6.54 + 0.28 by Houltz
B. et al. in 44 healthy children by nitrogen based LCI22. Mandaliya et. al. reported mean LCI value as 7.3+ 0.6 in the control group similiar to our
study21. Differences in the mean LCI values in
different countries requires to be investigated in the further studies.
Somatic growth, gender, ethinicity and age can be potential factors
explaining these discrepancy
Small sample size may be the major limitation of this study. Therefore,
multicenter studies including larger number of patients with CLM are
required. Also reference LCI values need to be defined in different
groups in larger population studies.
In conclusion, patients operated due to CLM may have impairment in the
peripheral airway function in the long term follow-up. Both spirometry
and LCI enabled detection of such an impairment in our study. But LCI
may be superior to detect changes earlier in the lung function