Department of Clinical Sciences, Faculty of Medicine, Lund University, Malmö, Sweden.
Department of Internal Medicine, Skåne University Hospital, Malmö, Sweden.
Europace. 2018 Sep 1;20(9):1535-1542. doi: 10.1093/europace/eux298.
We applied near-infrared-spectroscopy (NIRS) to measure absolute frontal cerebral tissue oxygen saturation (SctO2) during head-up tilt test (HUT) in patients investigated for unexplained syncope.
Synchronized non-invasive beat-to-beat haemodynamic monitoring, ECG, SctO2 (NIRS; normal range: 60-80%), and peripheral oxygen saturation (left hand, SpO2) were applied during HUT in a random sample of patients with unexplained syncope. Tracings of 54 patients (mean-age: 55 ± 19 years, 39% male) with negative HUT, vasovagal syncope (VVS), or orthostatic hypotension (OH) were analysed. In 44 patients HUT was diagnostic, in 10 HUT was negative. Thirty-one experienced VVS. Of these, 6 had spontaneous and 25 nitroglycerin-induced syncope. Thirteen patients had orthostatic hypotension (OH). Although there was no significant change in mean-arterial pressure from baseline to 1 min before syncope or end of passive HUT phase (-1.4 ± 13.9 mmHg; P = 0.45), there was a significant fall in SctO2 during the same period (-3.2 ± 3.2%; P ≤ 0.001). Among patients who experienced syncope, a decrease in SctO2 from 71 ± 5% at baseline to 53 ± 9% (P < 0.001) at syncope was observed. During HUT, there was a significant difference in delta SctO2 between spontaneous VVS (-4.5 ± 3.0%) and negative HUT (-1.3 ± 1.9%; P = 0.021), but not between spontaneous VVS and OH (-5.4 ± 4.2%; P = 0.65). In spontaneous VVS, progressive decrease of SctO2 was independent of mean arterial pressure decrease (P = 0.22).
Progressive decrease in cerebral tissue oxygenation independent of mean-arterial pressure may precede spontaneous vasovagal reflex during tilt. Patients experience syncope when SctO2 falls below 60%. These data confirm clinical utility of absolute cerebral oximetry monitoring for syncope investigation. We applied NIRS to measure frontal cerebral tissue oxygen saturation (SctO2) during head-up tilt test (HUT) in patients with unexplained syncope. In 44 of 54 patients, HUT was diagnostic. In patients with syncope, a significant SctO2-decrease was observed. Different patterns of SctO2 can be detected.
我们应用近红外光谱（NIRS）测量不明原因晕厥患者进行直立倾斜试验（HUT）期间的额部脑组织氧饱和度（SctO2）。
在不明原因晕厥患者的随机样本中，在 HUT 期间应用同步非侵入性逐搏血流动力学监测、心电图、SctO2（NIRS；正常范围：60-80%）和外周氧饱和度（左手，SpO2）。分析了 54 例（平均年龄：55±19 岁，39%为男性）HUT 阴性、血管迷走性晕厥（VVS）或体位性低血压（OH）患者的记录。在 44 例患者中，HUT 具有诊断意义，在 10 例中 HUT 为阴性。31 例患者出现 VVS。其中，6 例为自发性，25 例为硝酸甘油诱导性晕厥。13 例患者患有体位性低血压（OH）。尽管从基线到晕厥前 1 分钟或被动 HUT 阶段结束时平均动脉压没有显著变化（-1.4±13.9mmHg；P=0.45），但同一时期 SctO2 显著下降（-3.2±3.2%；P≤0.001）。在出现晕厥的患者中，SctO2 从基线时的 71±5%下降到晕厥时的 53±9%（P<0.001）。在 HUT 期间，自发性 VVS 与 HUT 阴性之间的 SctO2 差值有显著差异（-4.5±3.0%和-1.3±1.9%；P=0.021），但自发性 VVS 与 OH 之间无差异（-5.4±4.2%；P=0.65）。在自发性 VVS 中，SctO2 的逐渐下降与平均动脉压下降无关（P=0.22）。
在倾斜期间，独立于平均动脉压的脑组织氧合逐渐下降可能先于自主血管迷走反射。当 SctO2 下降到 60%以下时，患者会出现晕厥。这些数据证实了绝对脑氧饱和度监测在晕厥研究中的临床实用性。我们应用近红外光谱（NIRS）测量不明原因晕厥患者进行直立倾斜试验（HUT）期间的额部脑组织氧饱和度（SctO2）。在 54 例患者中的 44 例，HUT 具有诊断意义。在出现晕厥的患者中，SctO2 显著下降。可以检测到不同模式的 SctO2。
