[Approximate entropy of oxygen saturation and saturation impairment time index for the assessment of hypoxemia severity in obstructive sleep apnea hypopnea syndrome].
OBJECTIVE
To explore the clinical significance of two new indexes including approximate entropy of oxygen saturation (SpO2ApEn) and saturation impairment time index (SITi) in assessing the severity of hypoxemia in obstructive sleep apnea hypopnea syndrome (OSAHS) patients. In addition, to investigate the correlation betewwn new indexes and other parameters.


METHODS
The six hour polysomnography (PSG) of 500 patients with OSAHS and snorers in our hospital was retrospectively analyzed. According to the level of apnea hypopnea index (AHI) , subjects were divided into four subgroups, namely 113 healthy controls, 121 mild OSAHS, 118 moderate OSAHS, and 148 severe OSAHA patients.SpO2ApEn and SITi values among the four groups were compared.the correlations between SpO2ApEn, SITi and other parameters were analyzed, including AHI, oxygen desaturation index (ODI) , the lowest oxygen saturation (LSpO2) and the duration of oxygen saturation lower than 90% (T<90%). Next, taking AHI as the gold standard, the significance of SpO2ApEn and SITi in assessing the severity of hypoxemia in OSAHS patients was explored by ROC curve analysis.


RESULTS
SpO2ApEn and SITi between two each groups were significantly different (P < 0.001) and increased synchronously with AHI. Spearman correlation analysis showed that SpO2ApEn and SITi had a good correlation with AHI (correlation coefficient r = 0.765, r = 0.678, P < 0.01). SpO2ApEn and SITi also had a good correlation with ODI, LSpO2and T < 90%. According to the ROC analysis, the Boundary values of SpO2ApEn for mild, moderate and severe OSAHS patients were 16.70, 17.81, and 20.03, respectively, and the corresponding SITi values were 3.685, 4.055, and 4.445.


CONCLUSIONS
In this study, SpO2ApEn and SITi increased synchronously with AHI. SpO2ApEn and SITi had good correlations with AHI, ODI, LSpO2 and T < 90%. SpO2 ApEn and SITi have important clinical significance for assessment of hypoxia severity in OSAHS patients.
Jie
J
Liu
Department of Respiration, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences,Beijing 100730, China. Email:xiaoyipumch@sina.com.
Yi
Y
Xiao
D019277:Entropy; D006801:Humans; D010100:Oxygen / Q000097:blood*; D017286:Polysomnography; D012372:ROC Curve; D012189:Retrospective Studies; D012720:Severity of Illness Index; D020181:Sleep Apnea, Obstructive / Q000145:classification / Q000175:diagnosis / Q000503:physiopathology*
D010100:Oxygen