背景:夜间低氧负荷已被证明是一种稳健的,心力衰竭和射血分数(HFrEF)降低的患者的全因死亡率的独立预测因子,即使在呼吸事件频率低或可忽略不计的患者(呼吸暂停/呼吸不足)中,也以严重形式发生。这表明低氧血症负担存在两个组成部分:一个与呼吸事件无关,另一个与呼吸事件无关。这项研究的目的是表征这两个组成部分并评估其预后价值。
方法:通过测量血氧饱和度(SpO2)<90%(T90)的睡眠百分比,在280例HFrEF患者的队列中评估夜间低氧负担,和低于90%的SpO2曲线的面积(Area90)。这两个指标也在与呼吸事件相关的睡眠段内重新计算(事件相关成分:T90Eve,Area90Eve)和这些段之外(非特定组件:T90Nspec,Area90Nspec)。生存分析(Cox回归)的结果是全因死亡率。
结果:在60个月的中位随访期间,87名患者死亡。T90、Area90及其成分在单因素分析中具有显著性(P<0.05)。然而,当这些指数根据已知的风险因素进行调整时,T90,T90Nspec,Area90和Area90Nspec仍然具有统计学意义(p=0.018,风险比(HR)=1.12,95CI=(1.02,1.23);p=0.007,HR=1.20,95CI=(1.05,1.37);p=0.020,HR=1.05,95CI=(1.01,1.10);p=0.0006,HR=1.15,95CI=(1.06,1.25而T90Eve和Area90Eve没有(p=0.27,p=0.28)。使用引导重采样对这些结果进行了内部验证。
结论:通过证明非特异性低氧血症负担与全因死亡率的显著独立关联,本研究提示,总夜间低氧负荷的这一组成部分可能在HFrEF患者的预后中发挥重要作用.
BACKGROUND: Nocturnal hypoxemic burden has been shown to be a robust, independent predictor of all-cause mortality in patients with heart failure and reduced ejection fraction (HFrEF) and to occur in a severe form even in patients with low or negligible frequency of respiratory events (apneas/hypopneas). This suggests the existence of two components of hypoxemic burden: one unrelated to respiratory events and the other related. The aim of this study was to characterize these two components and to evaluate their prognostic value.
METHODS: Nocturnal hypoxemic burden was assessed in a cohort of 280 patients with HFrEF by measuring the percentage of sleep with an oxygen saturation (SpO2) <90% (T90), and the area of the SpO2 curve below 90% (Area90). Both indices were also recalculated within the sleep segments associated with respiratory events (event-related component: T90Eve, Area90Eve) and outside these segments (nonspecific component: T90Nspec, Area90Nspec). The outcome of the survival analysis (Cox regression) was all-cause mortality.
RESULTS: During a median follow-up of 60 months, 87 patients died. T90, Area90, and their components were significant in univariate analysis (P < .05 all). However, when these indices were adjusted for known risk factors, T90, T90Nspec, Area90, and Area90Nspec remained statistically significant (P = .018, hazard ratio (HR)=1.12, 95%CI=(1.02, 1.23); P = .007, HR=1.20, 95% CI = [1.05, 1.37]; P = .020, HR = 1.05, 95% CI = [1.01, 1.10]; P = .0006, HR = 1.15, 95% CI = [1.06, 1.25]), whereas T90Eve and Area90Eve did not (P = .27, P = .28). These results were internally validated using bootstrap resampling.
CONCLUSIONS: By demonstrating a significant independent association of nonspecific hypoxemic burden with all-cause mortality, this study suggests that this component of total nocturnal hypoxemic burden may play an important prognostic role in patients with HFrEF.