Discussion
At present, although there are a number of methods used for the
diagnosis and screening of OSAHS in children, they are not easy to apply
or correlate poorly with PSG[15]. Therefore, it is important to find
an economical, simple method of initial screening for OSAHS. This
article focuses on the value of nasopharyngeal lateral radiographs for
screening children with OSAHS.
Adenoid hypertrophy is a major cause of OSAHS in children. Adenoid size
was assessed by imaging methods, such as nasopharyngeal lateral
radiographs, CT and MRI[8,16-17]. In clinical practice,
nasopharyngeal lateral radiographs are easily accepted by children and
their parents for their effectiveness, tolerability and cost and are
commonly used in clinical practice. Since 1979, Fuiioka first described
A/N as an objective indicator of hypertrophy. Clinically, an A/N ratio
≥0.71 was considered indicative of pathological enlargement of the
adenoids[13,14]. Most studies have used the A/N ratio to assess
adenoid size and analyse their diagnostic value for OSAHS in children.
Selvadurai S et al[18] showed that adenoid hypertrophy was larger in
children with OSAHS than in those without OSAHS.Jain et al[19]
showed that the size of the adenoid correlated with the severity of
OSAHS. Our study showed similar results. Further analysis revealed that
the A/N ratio was positively correlated with OAHI (r=0.275), suggesting
that the A/N ratio can reflect the severity of OSAHS to a certain
extent; however, this correlation remains weak. The reason may be that
A/N can be used as an objective indicator of the size with adenoid; it
only shows the anterior and posterior diameter of the adenoid; however,
it does not reflect the size of the left and right diameter of the
adenoid. Additionally, other factors can also cause increased upper
airway resistance, such as severe allergic rhinitis and sinusitis.
Obesity and overweight can also cause OSAHS in children[20-22].
Interestingly, in the A/N≥0.80 group, the A/N ratio was negatively
correlated with OAHI (r=-0.208), which may explain why children with
adenoidhytrophy often present with mouth breathing to relieve upper
airway obstruction[23].
The pathophysiological changes of OSAHS are hypoxemia and hypercapnia,
especially in children[24]. The A/N ratio can be used to evaluate
not only the severity of OSAHS but also the degree of hypoxia in
patients. Brook et al.[7] suggested that the degree of adenoidal
hypertrophy is correlated with LSaO2. This study showed
that the A/N ratio was positively correlated with the ODI (r=0.227) and
negatively correlated with LSaO2 (r=-0.225). This is
consistent with the abovementioned study, but the correlations were
weak, likely because children with mouth breathing relieved upper airway
obstruction due to adenoid hypertrophy and because the duration of
apnoea in children was relatively shorter than that in adults.
Furthermore, the weak correlation may be related to the morphology of
adenoids.
The optimal cut-off value for the A/N
ratio was 0.825 for predicting OSAHS. When applying the cut-off value
for diagnosing OSAHS, the sensitivity was 45.1%, and the specificity
was 80.9%. This indicated that an A/N ratio ≥0.825 had certain
diagnostic value, and an A/N ratio ≥0.825 was identified as the main
influencing factor of OSAHS. However, Xu Z et al [25]suggested that
lateral nasopharyngeal radiographs can be screened for OSAHS in
children. The method is simple and economical and has a high application
value for primary hospitals and popularization studies of OSAHS.