Significance Of Apnea-hypopnea Duration In The Evaluation Of Symptoms And Severity Of Obstructive Sleep Apnea

Section 1: The Clinical Significance of Apnea-Hypopnea Duration in Evaluating Nocturnal Hypoxemia and Excessive Daytime Sleepiness in Patients with Obstructive Sleep Apnea Purpose To evaluate whether a novel parameter-the percentage of total sleep time spent with apnea-hypopnea duration time(AHT%)is better than the apnea-hypopnea index(AHI)for the assessment of nocturnal hypoxaemia and excessive daytime sleepiness(EDS)in obstructive sleep apnea(OSA)patients.Methods We conducted a retrospective study with 247 patients who were consecutively studied for suspected OSA from August 2018 to December 2019 in respiratory sleep center of the Second Affiliated Hospital of Anhui Medical University.Polysomnography(PSG)and the Epworth Sleepiness Scale(ESS)were used to evaluate the ability of AHT%and AHI to evaluate the severity of nocturnal hypoxemia and EDS.Exclusion criteria:(1)Age <18 years;(2)Central respiratory events accounting for more than 50%;(3)Patients with severe heart disease,liver and kidney dysfunction,and nervous system diseases;(4)Patients with chronic obstructive pulmonary disease,pulmonary heart disease,obesity,hypoventilation,pulmonary embolism and other patients with hypoxemia;(5)Monitor the patients undergoing pressure titration at night;(6)Patients who are using non-invasive ventilator assisted ventilation recently;(7)Long-term use of sedatives and hypnotics;(8)Portable sleep instrument was used to monitor patients;(9)The total sleep time is less than 5 hours;(10)Incomplete data.Classification of OSA severity was based on AHI(/h): AHI<5 is normal;5?AHI<15 is mild;15?AHI<30 is moderate;AHI?30 is severe.Results A total of 160 eligible participants were analysed,including 13 in the normal group,30 in the mild OSA group,19 in the moderate OSA group,and 98 in the severe OSA group.Median AHT% of normal,mild,moderate and severe OSA was 0.70%,4.85%,12.68% and 46.54%,respectively.Compared with normal,mild and moderate OSA,severe OSA has statistical significance in AHI,AHT%,minimum oxygen saturation(Min SpO₂),<90% saturation,and percentage of total sleep time with an O₂ saturation of <90%(CT90%).AHT% and AHI were closely correlated with CT90%(AHT% rs=0.889,AHI rs =0.874),Min SpO₂(AHT% rs=-0.778,AHI rs =-0.725)and average oxygen saturation(AHT% rs=-0.831,AHI rs =-0.822).With the aggravation of AHT% and AHI,the nocturnal oxygen saturation gradually decreased and the duration of hypoxemia prolonged,however,AHT% was more significantly associated with hypoxemia than AHI.The area under the curve(AUC= 0.632)of AHT% was higher than AHI(AUC=0.588)in predicting EDS(ESS?11)of OSA patients,and the difference was statistically significant(P <0.05).There were significant differences in AHT% between EDS population and non-EDS population,while AHI had no significant differences between the two groups,and the correlation between AHT% and EDS was stronger than AHI.Conculsions In this study,a new parameter AHT% was proposed to partially compensate for the AHI,which took into account both the frequency of apnea and hypoventilation as well as the duration of respiratory events in OSA patients,and more objectively reflected the prevalence of respiratory disorders throughout the night.AHT%was superior to AHI in the evaluation of nocturnal hypoxemia and EDS,and AHT%may be used for OSA diagnosis and severity grading in the future.Section 2: the Value of Mean Apnea-Hypopnea Duration in Severity Grading of Patients with Obstructive Sleep ApneaObjective To investigate the trend of mean apnea-hypopnea duration(MAD)in obstructive sleep apnea(OSA)patients and assess the value of MAD in assessing OSA severity.Methods We conducted a retrospective study with 235 patients who were consecutively studied for suspected OSA from September 2018 to January 2020 in respiratory sleep center of the Second Affiliated Hospital of Anhui Medical University.Polysomnography(PSG)was used to evaluate the variation trend of MAD with the apnea-hypopnea index(AHI)severity,analyze the relationship between MAD and night oxygen saturation to explore the significance of MAD in different OSA grouping methods.Exclusion criteria :(1)Age<18years;(2)Central respiratory events accounting for more than 50%;(3)Patients with severe heart disease,liver and kidney dysfunction,and nervous system diseases;(4)Patients with chronic obstructive pulmonary disease,pulmonary heart disease,obesity,hypoventilation,pulmonary embolism and other patients with hypoxemia;(5)Monitor the patients undergoing pressure titration at night;(6)Patients who are using non-invasive ventilator assisted ventilation recently;(7)Long-term use of sedatives and hypnotics;(8)Portable sleep instrument was used to monitor patients;(9)The total sleep time is less than 5 hours;(10)Incomplete data.Classification of OSA severity was based on AHI(/h): AHI<5 is normal;5?AHI<15 is mild;15?AHI<30 is moderate;AHI?30 is severe.Results 144 eligible patients were included in this study,including 28 patients in mild OSA group,16 patients in moderate OSA group,and 100 patients in severe OSA group.The MAD,the apnea hypopnea duration per hour(HAD)and the longest apnea duration(LAD)in the severe OSA group were significantly longer than those in the mild and moderate OSA groups.Patients with OSA were regrouped,with 30 and 60 as cut-off values.The longest MAD was not in the AHI?60 group(median,23.41 seconds)but in the 30<AHI<60 group(median,27.33 seconds),and the shortest MAD was in the AHI <30 group(median,19.04 seconds).The MAD was not correlated with the AHI and had a moderate negative correlation with the minimum oxygen saturation(Min SpO₂)and average oxygen saturation(Avg SpO₂)in the total population.In the AHI<60 group,the MAD was positively correlated with the AHI,but the MAD was negatively correlated with the AHI in the AHI?60 group.The correlations between the MAD and the Min SpO₂ and Avg SpO₂ were not statistically significant in the AHI?60 group.The correlation between the HAD and oxygen saturation was stronger than the MAD in all groups.Conclusions For the first time,this study found that OSA patients with significantly prolonged MAD were distributed in the 30?AHI<60 group,while the MAD of extremely severe OSA patients was shortened,and the MAD presented a trend of first increasing and then decreasing with the increase of AHI.The MAD only considers the duration of respiratory events,but does not consider the degree of hypoxemia and the frequency of respiratory events.The MAD alone cannot be used to determine the severity of OSA.The correlation between HAD and blood oxygen saturation is stronger than MAD,and the clinical application value may be greater than MAD.Considering the special pathophysiological characteristics of OSA with AHI?60/h,it is suggested that the subgroup of OSA severity be increased.