Department of Biomedical Engineering of Montescano Institute, Istituti Clinici Scientifici Maugeri IRCCS, Laboratory for the Study of Ventilatory Instability, Montescano, PV, Italy.
Department of Biomedical Engineering of Montescano Institute, Istituti Clinici Scientifici Maugeri IRCCS, Laboratory for the Study of Ventilatory Instability, Montescano, PV, Italy.
Am Heart J. 2024 Oct;276:1-11. doi: 10.1016/j.ahj.2024.06.011. Epub 2024 Jul 6.
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.
Nocturnal hypoxemic burden was assessed in a cohort of 280 patients with HFrEF by measuring the percentage of sleep with an oxygen saturation (SpO) <90% (T90), and the area of the SpO curve below 90% (Area90). Both indices were also recalculated within the sleep segments associated with respiratory events (event-related component: T90, Area90) and outside these segments (nonspecific component: T90, Area90). The outcome of the survival analysis (Cox regression) was all-cause mortality.
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, T90, Area90, and Area90 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 T90 and Area90 did not (P = .27, P = .28). These results were internally validated using bootstrap resampling.
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.
夜间低氧负荷已被证明是射血分数降低的心力衰竭（HFrEF）患者全因死亡率的一个强有力的独立预测因素，即使在呼吸事件（呼吸暂停/低通气）频率较低或可忽略不计的患者中，也会出现严重的低氧血症。这表明低氧血症负担有两个组成部分：一个与呼吸事件无关，另一个与呼吸事件有关。本研究的目的是描述这两个组成部分，并评估它们的预后价值。
通过测量睡眠期间氧饱和度（SpO ）<90%的时间百分比（T90）和 SpO 曲线下面积<90%（Area90），评估 280 例 HFrEF 患者的夜间低氧血症负担。这两个指数也在与呼吸事件相关的睡眠段（事件相关成分：T90、Area90）和这些段之外（非特异性成分：T90、Area90）进行重新计算。生存分析（Cox 回归）的结果是全因死亡率。
在中位随访 60 个月期间，87 例患者死亡。T90、Area90 及其成分在单因素分析中具有显著性（均 P<0.05）。然而，当这些指数根据已知的危险因素进行调整时，T90、T90、Area90 和 Area90 仍然具有统计学意义（P=0.018，风险比（HR）=1.12，95%可信区间（CI）=（1.02，1.23）；P=0.007，HR=1.20，95%CI=[1.05，1.37]；P=0.020，HR=1.05，95%CI=[1.01，1.10]；P=0.0006，HR=1.15，95%CI=[1.06，1.25]），而 T90 和 Area90 则没有（P=0.27，P=0.28）。这些结果使用自举重采样进行了内部验证。
本研究通过证明非特异性低氧血症负担与全因死亡率之间存在显著的独立相关性，表明总夜间低氧血症负担的这一部分可能在 HFrEF 患者中发挥重要的预后作用。
