Risk factors of sleep-disordered breathing in haemodialysis patients

Background
Sleep-disordered breathing (SDB) is common in patients with kidney disease; but often underdiagnosed as it is infrequently assessed in clinical practice. The objective of this study was to assess the risk factors of SDB in haemodialysis patients, and to identify useful assessment tools to detect SDB in this population.
Methods
We used nocturnal oximetry, Epworth Sleepiness Scale (ESS) and STOPBANG questionnaire to screen for SDB in haemodialysis patients. Presence of SDB was defined by Oxygen desaturation index (ODI≥5/h), and further confirmed by apnoea-hypopnea index (AHI) from an in-laboratory polysomnography. Blood samples were collected prior to commencing a haemodialysis treatment.
Results
SDB was detected in 70% of participants (N = 107, mean age 67 years). STOPBANG revealed that 89% of participants were at risk of SDB; however, only 17% reported daytime sleepiness on the ESS. Of the participants who underwent polysomnography (n = 36), obstructive sleep apnoea was identified in 86%, and median AHI was 34.5/h. Oximetry and AHI results were positively correlated (r = 0.62, P = 0.0001), as were oximetry and STOPBANG (r = 0.48; P<0.0001), but not ESS (r = 0.19; P = 0.08). Multivariate analysis showed that neck circumference (OR: 1.20; 95% CI: 1.07–1.34; P = 0.02) and haemoglobin (OR: 0.93; 95% CI: 0.88–0.97; P = 0.003) were independently associated with the presence of SDB.
Conclusion
Dialysis patients with a large neck circumference and anaemia are at risk of SDB; using nocturnal oximetry is practical and reliable to screen for SDB and should be considered in routine management of dialysis patients, particularly for those who demonstrate risk factors.

背景：睡眠呼吸障碍（Sleep-disordered breathing, SDB）在肾病患者中颇为常见，但由于临床实践中鲜有开展相关评估，该病常被漏诊。本研究旨在探讨血液透析患者发生睡眠呼吸障碍的危险因素，并筛选适用于该人群睡眠呼吸障碍筛查的有效评估工具。

方法：本研究采用夜间血氧监测、爱泼沃斯嗜睡量表（Epworth Sleepiness Scale, ESS）及STOPBANG问卷对血液透析患者进行睡眠呼吸障碍筛查。以氧减饱和度指数（Oxygen desaturation index, ODI≥5次/小时）定义睡眠呼吸障碍的存在，并通过实验室多导睡眠图（polysomnography）检测的呼吸暂停低通气指数（apnoea-hypopnea index, AHI）进一步确认。血液样本采集于血液透析治疗开始前。

结果：70%的受试者被检出存在睡眠呼吸障碍（N = 107, 平均年龄67岁）。STOPBANG问卷显示89%的受试者存在睡眠呼吸障碍风险，但仅有17%的受试者在爱泼沃斯嗜睡量表中报告日间嗜睡。在接受多导睡眠图检测的受试者（n = 36）中，86%被确诊为阻塞性睡眠呼吸暂停，呼吸暂停低通气指数的中位数为34.5次/小时。血氧监测结果与呼吸暂停低通气指数呈正相关（r = 0.62, P = 0.0001），血氧监测与STOPBANG问卷结果亦呈正相关（r = 0.48; P<0.0001），但与爱泼沃斯嗜睡量表无显著相关性（r = 0.19; P = 0.08）。多因素分析显示，颈围（比值比（Odds Ratio, OR）: 1.20; 95%置信区间（Confidence Interval, CI）: 1.07–1.34; P = 0.02）与血红蛋白水平（OR: 0.93; 95% CI: 0.88–0.97; P = 0.003）是与睡眠呼吸障碍发生独立相关的因素。

结论：颈围较大及存在贫血的血液透析患者罹患睡眠呼吸障碍的风险更高；夜间血氧监测操作便捷且结果可靠，可用于睡眠呼吸障碍的筛查，应将其纳入血液透析患者的常规管理流程，尤其针对存在相关危险因素的患者。