The prevalence of obstructive sleep apnea (OSA) has been increasing year by year, but the current diagnostic criteria of apnea-hypopnea index (AHI) >5 times/h commonly used for OSA has gradually revealed drawbacks in the diagnosis, severity evaluation, treatment effect and long-term complications prediction of the disease. This study proposed that there is a need for more information about the duration of apnea-hypopnea for assessing OSA in addition to AHI.

To investigate the significance of duration of respiratory events in nocturnal hypoxemia in adults with OSA.

A total of 296 patients with suspected OSA who were admitted to the sleep monitoring room of the First Hospital of Shanxi Medical University from October 2021 to March 2022 were selected as the study subjects. Before PSG, the subjects underwent a physical examination in terms of height, body mass, neck circumference, and were asked about their sleep history, as well as history of hypertension and diabetes. The subjects were divided into three groups according to AHI of 5 times/h≤AHI<15 times/h as the mild OSA group (n=56), 15 times/h≤AHI<30 times/h as the moderate OSA group (n=62), AHI≥30 times/h as the severe OSA group (n=178). The three groups were compared for blood oxygen indexes[lowest oxygen saturation (LSpO₂), mean oxygen saturation (MSpO₂), baseline oxygen saturation (BSpO₂), oxygen desaturation index (ODI), oxygen saturation (SpO₂) below 90% in total sleep time (T90) ]and duration parameters of respiratory events [mean total apnea duration (MTAD), mean hypopnea duration (MHD), mean apnea-hypopnea duration (MAD), the longest apnea duration (LTAD), the longest hypopnea duration (LHD), the longest apnea-hypopnea duration (LAD), total apnea-hypopnea duration (TAD), AHI, percentage of apnea/hypopnea time from total sleep time (AHT%) ]. Spearman rank correlation analysis was used to investigate the correlation between respiratory event duration parameters and blood oxygen indexes. The OSA patients were divided into the short event group (short TAD subgroup, short AHT% subgroup, n=74) and long event group (long TAD subgroup, long AHT% subgroup, n=222) according to the median of TAD and AHT% (69.78 min and 14.33%, respectively), and the correlation of TAD, AHT% and AHI with blood oxygen indexes in each group was further analyzed.

There were significant differences in gender, age, BMI, neck circumference, daytime sleepiness, history of hypertension and diabetes among the mild, moderate and severe OSA groups (P<0.05). ODI and T90 in the severe OSA group were higher than those in the mild and moderate OSA groups, and LSpO₂ and MSpO₂ were lower than those in the mild and moderate OSA groups (P<0.05) ; LSpO₂ in the moderate OSA group was lower than that in the mild OSA group, ODI and T90 were higher than that in the mild OSA group (P<0.05). MTAD, LTAD, TAD, AHT% in the severe OSA group were higher than those in the mild and moderate OSA groups, and MHD was lower than that in the mild and moderate OSA groups (P<0.05) ; LHD in the severe OSA group was lower than that in the moderate OSA group, LAD was higher than that in the mild OSA group. MTAD, LTAD, TAD and AHT% in the moderate OSA group were higher than those in the low OSA group (P<0.05). The scatter plot and loess fitting curve showed that the values of MTAD, MHD, MAD, LTAD, LHD and LAD all increased first and then decreased with AHI. TAD and AHT% were prolonged with increasing AHI. Spearman rank correlation analysis showed that AHI, MTAD, LTAD, TAD, AHT% were negatively correlated with LSpO₂ and MSpO₂, but positively correlated with ODI and T90 in OSA patients (P<0.05) ; MHD and LHD were positively correlated with LSpO₂ and MSpO₂, and negatively correlated with ODI and T90 (P<0.05) ; MAD was negatively correlated with ODI (P<0.05) ; LAD was negatively correlated with LSpO₂ (P<0.05). Further subgroup Spearman rank correlation analysis showed that TAD, AHT% and AHI were negatively correlated with LSpO₂ and positively correlated with ODI in short TAD subgroup, short AHT% subgroup, long TAD subgroup and long AHT% subgroup (P<0.05), and had no correlation with BSpO₂ (P>0.05) ; TAD, AHT%, and AHI were all negatively correlated with MSpO₂ and positively correlated with T90 in the long event group (P<0.05) .

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 index AHI, and indexes such as TAD and AHT% are even more representative than AHI in some cases. The combination of AHI and LSpO₂ with the duration of respiratory events can more objectively assess the severity of OSA patients.

阻塞性睡眠呼吸暂停（OSA）患病率逐年升高，但目前OSA普遍使用呼吸暂停低通气指数（AHI）>5次/h的诊断标准对疾病的诊断、评估病情的严重程度、治疗效果以及远期并发症的预测中逐渐暴露出弊端，本研究提出评估OSA的参数除了AHI外，还需纳入更多关于呼吸暂停低通气时间的信息。

探讨呼吸事件持续时间在成年人阻塞性睡眠呼吸暂停夜间低氧血症中的意义。

选取2021年10月—2022年3月就诊于山西医科大学第一医院睡眠监测室疑诊为OSA的患者296例作为研究对象。在进行多导睡眠监测（PSG）前，受试者均接受了身高、体质量、颈围等方面的体格检查，并详细询问了其睡眠史以及高血压及糖尿病史等信息。根据AHI将受试者分为3组：5次/h≤AHI<15次/h为轻度OSA组（56例），15次/h≤AHI<30次/h为中度OSA组（62例），AHI≥30次/h为重度OSA组（178例）。比较3组血氧指标[最低血氧饱和度（LSpO₂）、平均血氧饱和度（MSpO₂）、基线血氧饱和度（BSpO₂）、氧减指数（ODI）及血氧饱和度（SpO₂）<90%的时间占整夜总睡眠时间的百分比（T90）]和呼吸事件持续时间参数[平均呼吸暂停持续时间（MTAD）、平均呼吸低通气持续时间（MHD）、平均呼吸暂停-低通气持续时间（MAD）、总呼吸暂停时间最长值（LTAD）、最长低通气时间（LHD）、最长呼吸暂停-低通气持续时间（LAD）、总呼吸暂停-低通气持续时间（TAD）、AHI、呼吸暂停-低通气持续时间占总睡眠时间百分比（AHT%）]的差异，采用Spearman秩相关分析探讨呼吸事件持续时间参数与血氧指标的相关性。根据TAD和AHT%的中位数（分别为69.78 min和14.33%），将OSA患者分为短事件组（短TAD亚组、短AHT%亚组，各74例）和长事件组（长TAD亚组、长AHT%亚组，各222例），并进一步分析各组TAD、AHT%和AHI与血氧指标的相关性。

轻、中、重度OSA组患者性别、年龄、BMI、颈围、日间嗜睡、高血压史、糖尿病史比较，差异均有统计学意义（P<0.05）。重度OSA组患者ODI、T90均高于轻、中度OSA组，LSpO₂、MSpO₂低于轻、中度OSA组（P<0.05）；中度OSA组LSpO₂低于轻度OSA组，ODI、T90高于轻度OSA组（P<0.05）。重度OSA组MTAD、LTAD、TAD、AHT%均高于轻、中度OSA组，MHD低于轻、中度OSA组（P<0.05）；重度OSA组LHD低于中度OSA组，LAD高于轻度OSA组；中度OSA组MTAD、LTAD、TAD、AHT%高于低度OSA组（P<0.05）。散点图及loess拟合曲线结果显示，MTAD、MHD、MAD、LTAD、LHD、LAD数值均随着AHI先增大，后减小；TAD、AHT%随着AHI的增大而延长。Spearman秩相关分析结果显示，OSA患者AHI、MTAD、LTAD、TAD、AHT%与LSpO₂、MSpO₂呈负相关，与ODI、T90呈正相关（P<0.05）；MHD、LHD与LSpO₂、MSpO₂呈正相关，与ODI、T90呈负相关（P<0.05）；MAD与ODI呈负相关（P<0.05）；LAD与LSpO₂呈负相关（P<0.05）。进一步分组Spearman秩相关分析结果显示，短TAD亚组、短AHT%亚组、长TAD亚组、长AHT%亚组中TAD、AHT%、AHI与LSpO₂均呈负相关，与ODI均呈正相关（P<0.05），与BSpO₂无相关性（P>0.05）；长事件组中TAD、AHT%、AHI与MSpO₂均呈负相关，与T90均呈正相关（P<0.05）。

呼吸事件持续时间在评价OSA患者的夜间低氧血症中发挥着重要作用，可以作为现有诊断及评价指标AHI的补充，并且TAD、AHT%等指标在某些情况下甚至比AHI更具有代表性。AHI、LSpO₂联合呼吸事件持续时间能更客观地评估OSA患者病情严重程度。