Significance Of Duration Of Respiratory Events In Nocturnal Hypoxemia In Adults With Obstructive Sleep Apnea

Objective:The objective of this study was to address the limitation of AHI in accurately assessing the severity of OSA in clinical settings.To achieve this goal,the study analyzed the duration parameters of each respiratory event recorded in PSG and compared their significance in the assessment of nocturnal hypoxemia with the number of respiratory events.Methods:In this study,we collected suspected OSA patients admitted to the Sleep Monitoring Room of the Department of Respiratory and Critical Care Medicine at The First Hospital of Shanxi Medical University from October 2021 to March 2022.After screening for inclusion and exclusion criteria,296 subjects were included.Before the test,all subjects underwent physical examinations,including height,weight,neck circumference,and blood pressure,and were asked about their sleep history,hypertension,and diabetes.After polysomnography monitoring,the subjects were divided into four groups based on OSA severity: simple snoring,mild OSA,moderate OSA,and severe OSA.Differences in blood oxygen indexes and respiratory event duration parameters between groups were compared to understand the correlation between respiratory event duration and blood oxygen indexes.All subjects with a definite diagnosis of OSA were regrouped into short TAD,long TAD,short AHT%,and long AHT% groups based on the median of 69.78 and 14.33%,and the correlation between TAD and AHT% and blood oxygen index was further compared in each group after regrouping.Results:1.There were significant differences in gender,age,BMI,neck circumference,daytime sleepiness,hypertension and diabetes among mild,moderate and severe OSA groups(P < 0.05).2.OSA patients with definite diagnosis were divided into mild,moderate and severe groups using AHI cut-off points of 5,15 and 30 times /h.The results showed that LSp O2,MSp O2,ODI and T90 had statistical significance among the three groups(P <0.01).ODI and T90 in severe group were higher than those in mild and moderate groups,while LSp O2 and MSp O2 were lower than those in mild and moderate groups.The LSp O2 in moderate group was lower than that in mild group(P < 0.01).There was no significant difference in BSp O2 among light,medium and heavy groups(P > 0.05).There were significant differences in MTAD,MHD,LTAD,LHD,LAD,TAD and AHT%among mild,moderate and severe groups(P < 0.05).The MTAD,LTAD,TAD and AHT% of severe group were higher than those of mild and moderate group,while the MHD was lower than that of mild and moderate group.LHD in severe group was lower than that in moderate group,and LAD in mild group was higher.The MTAD,LTAD,TAD,AHT% in moderate group was higher than that in low group,and the difference was statistically significant(P < 0.05).There was no significant difference in MAD among the three groups(P > 0.05).3.In order to make clear the relationship between each time parameter and AHI more clearly,the scatter graph of each time duration parameter and AHI is drawn respectively,and a fitting curve is added.As can be seen from the figure,the values of MTAD,MHD,MAD,LTAD,LHD and LAD increased first and then decreased with AHI.TAD and AHT% were prolonged with the increase of AHI.4.By Pearson test,AHI,MTAD,LTAD,TAD,AHT% of OSA patients were negatively correlated with LSp O2 and MSp O2(r < 0,P < 0.01),and positively correlated with ODI and T90(r > 0,P < 0.01).MHD and LHD were positively correlated with LSp O2 and MSp O2,but negatively correlated with ODI and T90.MAD was negatively correlated with ODI.LAD was negatively correlated with LSp O2,with statistical significance(P < 0.05).All respiratory event duration parameters involved in this study had no significant correlation with BSp O2(P > 0.05).Compared with AHI,TAD and AHT% were more strongly correlated with LSp O2,MSp O2 and T90.On ODIs,however,AHI showed a stronger correlation.5.OSA patients were regrouped into short event group(short TAD group,short AHT% group)and long event group(long TAD group,long AHT% group)according to the median values of 69.78 and 14.33%.The results showed that,TAD,AHT% and AHI in the long event group were correlated with LSp O2,MSp O2,ODI and T90,and were higher than those in the short event group.TAD,AHT% and AHI were negatively correlated with LSp O2 and MSp O2(r=-0.377,-0.471,-0.642,-0.584,-0.250,-0.584,-0.539,-0.360,-0.487,-0.640,-0.583,-0.274,-0.589,-0.540,P < 0.05),were positively correlated with ODI and T90(r=0.528,0.766,0.806,0.962,0.690,0.643,0.570,0.741,0.841,0.962,0.244,0.705,0.645,P < 0.05)and had no correlation with BSp O2(P >0.05).In the short event group,the correlation between AHI and LSp O2,MSp O2,ODI and T90 was greater than that of TAD and AHT%,but in the long event group,the correlation between TAD and AHT% and LSp O2,MSp O2 and T90 was higher than that of AHI and that of ODI was lower than that of AHI.Conclusion:1.Duration of respiratory events plays an important role in the evaluation of nocturnal hypoxemia in OSA patients,and can be used as a supplement to the existing diagnostic and evaluation indicators AHI,and TAD,AHT% and other indicators are even more representative than AHI in some cases.2.In OSA disease studies,duration of AHI and LSp O2 combined respiratory events can more objectively assess the severity of OSA patients.