Abstract: 　Objective　To analyze the clinical and polysomnography (PSG) characteristics of obstructive sleep apnea hypopnea syndrome (OSAHS) in children. Methods　The children with symptoms of snoring or/with open mouth breathing from December 2016 to April 2019 were selected as the research object, and their clinical data and PSG monitoring results were collected. According to the PSG results, the patients were divided into OSAHS group, primary snoring (PS) group and snoring with hypoxia group, and the clinical data and PSG results of the three groups were analyzed. Results　A total of 408 (260 boys and 148 girls) children were enrolled and median age was 5 years (4~7 years). There were 99 cases of OSAHS, 201 cases of PS and 42 cases of snoring with hypoxia. Compare with PS group, the proportion of tonsillar enlargement and adenoid hypertrophy, the proportion of nocturnal snoring, laborious breathing, apnea and nocturia were higher, and the proportion of rhinitis/sinusitis was lower in OSAHS group. The rate of daytime drowsiness in OSAHS group was higher than that in PS group and snoring with hypoxia group, and there were significant differences (all P<0.05). The sleep time of no rapid eye movement (NREM1) and snoring index monitored by PSG were higher in OSAHS group than those in PS group, and the proportion of stage 3 NREM sleep was lower than that in PS group. The lowest blood oxygen saturation (LSaO2) of OSAHS group and snoring with hypoxia group was lower than that of PS group, and the difference was statistically significant (P<0.05). OSAHS group had the highest apnea hypopnea index (AHI) and the longest time of apnea, followed by snoring with hypoxia group, and the difference was statistically significant (P<0.05). Multivariate logistic regression analysis showed that adenoid hypertrophy, obesity and the presence of allergic rhinitis/sinusitis were independent risk factors for OSAHS in children (P<0.05). Conclusion　Children with OSAHS have disordered sleep structure, mainly the prolonged sleep time of NREM1 and shortened time of NREM3. Obesity, adenoid hypertrophy, rhinitis or sinusitis are risk factors for OSAHS.

Key words: 　obstructive sleep apnea hypopnea syndrome;　clinical characteristics;　polysomnography;　child