Intradialytic hypotension (IDH) is a hemodynamic phenomenon recently associated with decreased blood oxygen saturation (SO₂). The ratio between peripheral oxygen saturation (SpO₂) and central venous SO₂ (ScvO₂) or Oxygen Extraction Ratio (OER), which represents a roughly estimate of the amount of oxygen claimed by peripheral tissues, might be used to estimate haemodialysis (HD) related hypoxic stress. Aim of this pilot study was to evaluate the relationship between OER increments during dialysis sessions (ΔOER) and episodes of IDH. We enrolled chronic HD patients with permanent central venous catheter (CVC) and no fistula, in whom ScvO₂ measurement is at hand. OER ([(SpO₂ − ScvO₂)/SpO₂] × 100) was measured in three consecutive HD sessions (HD OER sessions) before HD, after 15′, 30′ and 60′ min and at the end of HD. Then, a one-year follow-up was planned to record the number of IDH episodes. In the 28 enrolled patients (age 74 ± 2.6 years), during 12 ± 1.2 months of follow up, incidence of IDH was 3.6%. We divided patients into two groups, above or below the median value of ΔOER at the end of HD, which was 36%. In these groups, the average incidence of IDH was 7% and 2% respectively (p < 0.01), while OER values before HD were not different. Notably, in the high ΔOER group the OER increment was evident since after 15′ and was significantly higher than in the low ∆OER group (∆OER-15′ = 19 ± 3.0% vs. 9.0 ± 3.0%; p < 0.05). By comparison, blood volume changes overlapped in the two groups (average change − 9 ± 0.8%). Values of ∆OER > 19% after only 15′ of HD treatment or > 36% at the end of the session characterize patients with higher rates of hypotension. Intradialytic ∆OER, a parameter of tissue hypoxic stress, identifies more fragile patients at greater risk of IDH.

透析中低血压 (IDH) 是一种最近与血氧饱和度降低 (SO ₂ )相关的血液动力学现象。外周血氧饱和度 ( SpO ₂ ) 与中心静脉 SO ₂ (ScvO ₂ ) 或氧提取率 (OER) 之间的比率，它代表外周组织要求的氧气量的粗略估计，可用于估计血液透析 (HD ) 相关的缺氧压力。该试点研究的目的是评估透析期间 OER 增量 (ΔOER) 与 IDH 发作之间的关系。我们招募了具有永久性中心静脉导管 (CVC) 且无瘘管的慢性 HD 患者，这些患者可以进行 ScvO ₂测量。OER ([(  SpO ₂ − ScvO₂ )/血氧饱和度₂] × 100) 在 HD 之前、15'、30' 和 60' 分钟之后以及 HD 结束时在三个连续的 HD 会话（HD OER 会话）中测量。然后，计划进行为期一年的随访以记录 IDH 发作的次数。在纳入的 28 名患者（年龄 74 ± 2.6 岁）中，在 12 ± 1.2 个月的随访期间，IDH 的发生率为 3.6%。我们将患者分为两组，高于或低于 HD 结束时 ΔOER 的中值，即 36%。在这些组中，IDH 的平均发生率分别为 7% 和 2%（p < 0.01），而 HD 前的 OER 值没有差异。值得注意的是，在高 ΔOER 组中，自 15' 之后 OER 增加很明显，并且显着高于低 ΔOER 组（ΔOER-15' = 19 ± 3.0% 对 9.0 ± 3.0%；p < 0.05）。相比之下，两组的血容量变化重叠（平均变化 - 9 ± 0.8%）。仅在 HD 治疗 15 分钟后 ΔOER 值 > 19% 或在治疗结束时 > 36% 表示低血压发生率较高的患者。透析中 ∆OER 是组织缺氧应激的一个参数，可识别出 IDH 风险更大的脆弱患者。