Evaluation of reoxygenation slope using Near-infrared spectroscopy in intensive care patients

Objective: To evaluate the reoxygenation slope reactivity in intensive care patients using near-infrared spectrophotometry (NIRS).

Design: an observational prospective study.

Setting: A 15-beds intensive care unit of a teaching hospital

Patients: Consecutive patients admitted to the intensive care unit with severe sepsis (Sepsis; n=25 patients), without sepsis (Control; n=22 patients); a group of healthy volunteers (n=50).

Measurements: Baseline thenar muscle tissue oxygen saturation (StO2), Maximal StO2 reperfusion slope and the area under the curve for the hyperhemic response were measured during and after a 150 seconds arterial occlusion. Measurements were performed at the early phase of hospitalization and compared to measurements obtained in healthy volunteers.

Results: Mean initial StO2 values were comparable between the 3 groups. During arterial occlusion, maximal StO2 reperfusion slope was higher in healthy volunteers (361 ± 137 %.min-1), as compared to both Sepsis (111.3 ± 56.9 %.min-1; p=0.0002) and Control groups (163.3 ± 120.5 %.min-1; p=0.01). Maximal StO2 reperfusion slope was comparable between Sepsis and Control (p=0.55). In Sepsis, StO2 reperfusion slope and the area under the curve for the hyperemic response were similar whatever the mean arterial pressure or the blood lactate levels.

Conclusion: Microvascular postocclusive reactivity assessed by NIRS is significantly altered on admission within ICU patients, as compared to healthy volunteers. However, In contrast to our expectancies, no difference was observed between Sepsis and Control.

研究目的：采用近红外分光光度法（near-infrared spectrophotometry, NIRS）评估重症监护病房患者的复氧斜率反应性。
研究设计：一项观察性前瞻性研究。
研究场景：某教学医院的15张床位重症监护病房。
研究对象：连续纳入的重症监护病房住院患者，其中重症脓毒症组（Sepsis；n=25例）、非脓毒症对照组（Control；n=22例），以及健康志愿者组（n=50例）。
测量指标：在150秒动脉阻断期间及阻断后，测量基线时的鱼际肌组织氧饱和度（StO2）、最大StO2复灌斜率，以及高血流反应的曲线下面积。分别于住院早期开展测量，并与健康志愿者的测量结果进行对比。
研究结果：3组受试者的初始StO2均值无统计学差异。动脉阻断期间，健康志愿者组的最大StO2复灌斜率为361 ± 137 %.min⁻¹，显著高于重症脓毒症组（111.3 ± 56.9 %.min⁻¹；p=0.0002）与对照组（163.3 ± 120.5 %.min⁻¹；p=0.01）。重症脓毒症组与对照组的最大StO2复灌斜率无统计学差异（p=0.55）。在重症脓毒症组中，无论平均动脉压或血乳酸水平如何，StO2复灌斜率与高血流反应的曲线下面积均无显著差异。
研究结论：与健康志愿者相比，重症监护病房患者入院时通过NIRS评估的微血管闭塞后反应性显著受损。但与本研究的预期不符的是，重症脓毒症组与对照组之间未观察到显著差异。