麻醉監(jiān)測||腦外污染對局部腦血氧飽和度監(jiān)測的影響

麻醉監(jiān)測||腦外污染對局部腦血氧飽和度監(jiān)測的影響(圖1)

摘要譯文（供參考）

器官捐獻期間揭示的腦外污染對近紅外光譜的影響：腦死亡器官捐獻者的前瞻性觀察研究

背景：

近紅外光譜（Near-infrared spectroscopy ，NIRS）已廣泛用于麻醉和重癥監(jiān)護，以監(jiān)測局部腦血氧飽和度（regional
cerebral oxygen saturation，rScO2）。腦外組織的正常氧合可能會覆蓋并掩蓋腦飽和度下降，這種現(xiàn)象稱為腦外污染。我們研究了停止腦外組織灌注對腦缺氧患者 rScO2 的影響。

方法：

在一項單中心、前瞻性、觀察性研究中，對接受器官捐獻的腦死亡成年人進行了調(diào)查。使用 INVOS 5100c/7100 和 ForeSight Elite 系統(tǒng)同時測量 rScO2。為了實現(xiàn)器官的有效保護并防止灌注液重新分布到其他組織，在器官灌注之前夾緊主動脈。監(jiān)測 rScO2 直到主動脈鉗夾后至少 40 分鐘。主要結(jié)局指標是通過主動脈鉗夾后rScO2絕對值降低來量化的腦外污染量。次要結(jié)局指標是鉗夾前后獲得的rScO2絕對值。

結(jié)果：

包括12名器官捐獻者。將INVOS（43.0 ± 9.5%）與 ForeSight
（p<0.001）。在主動脈鉗夾之前，INVOS（63.8±6.2%）和ForeSight監(jiān)測儀（67.7±6.5%）獲得了接近正常的rScO2值。夾閉30分鐘后，rScO2顯著下降（p<0.001）至20.8%±7.8%（INVOS）和39.9±8.1%（ForeSight），即腦外組織和腦組織均去飽和。（27.8 ± 7.1%）監(jiān)測儀進行比較時，主動脈鉗夾導(dǎo)致 rScO2 的絕對值顯著降低

結(jié)論：

由主動脈鉗夾引起的腦外污染的突然結(jié)束，在相當大的程度上影響了兩臺近紅外監(jiān)測儀。INVOS和ForeSight監(jiān)測器都無法檢測到在正常腦外氧合條件下的嚴重腦缺氧/缺氧。雖然這兩種近紅外監(jiān)測儀都可以指導(dǎo)優(yōu)化頭部動脈供氧的措施，但不應(yīng)將其用于檢測孤立的腦血飽和度下降。

原文摘要

The effect of extracerebral contamination on near infrared spectroscopy as revealed during organ donation: A prospective observational study in brain dead organ donors

Abstract

Background:Near-infrared spectroscopy (NIRS) has been utilized widely in anesthesia and intensive care to monitor regional cerebral oxygen saturation (rScO2). A normal oxygenation of extracerebral tissues may overlay and thereby mask cerebral desaturations, a phenomenon known as extracerebral contamination. We investigated the effect of a cessation of extracerebral tissue perfusion on rScO2 in patients with anoxic brains.

Methods:In a single-center, prospective, observational study, brain dead adults undergoing organ donation were investigated. rScO2 was measured bifrontally using the INVOS 5100c/7100 as well as the ForeSight Elite system. To achieve an efficient conservation of organs and to prevent a redistribution of the perfusion fluid to other tissues, the aorta was clamped prior to organ perfusion. rScO2 was monitored until at least forty minutes after aortic clamping. The primary outcome was the amount of extracerebral contamination as quantified by the absolute decrease in rScO2 after aortic clamping. Secondary outcomes were the absolute rScO2-values obtained before and after clamping.

Results:Twelve organ donors were included. Aortic clamping resulted in a significantly (p<0.001) greater absolute decrease in rScO2 when comparing the INVOS (43.0 ± 9.5%) to the ForeSight (27.8 ± 7.1%) monitor. Before aortic clamping, near normal rScO2-values were obtained by the INVOS (63.8 ± 6.2%) and the ForeSight-monitor (67.7 ± 6 .5%). The rScO2 significantly (p<0.001) dropped to 20.8 ± 7.8% (INVOS) and 39.9 ± 8.1% (ForeSight) thirty minutes after clamping, i.e. a condition of a desaturation of both extracerebral and cerebral tissues.

Conclusions:The abrupt end of extracerebral contamination, caused by aortic clamping, affected both NIRS monitors to a considerable extent. Both the INVOS and the ForeSight-monitor were unable to detect severe cerebral hypoxia/anoxia under conditions of normal extracerebral oxygenation. While both NIRS-monitors may guide measures to optimize arterial oxygen supply to the head, they should not be used with the intention to detect isolated cerebral desaturations.

麻醉監(jiān)測||腦外污染對局部腦血氧飽和度監(jiān)測的影響(圖2)