Noninvasive cerebral oximetry during endovascular therapy for acute ischemic stroke: an observational study

Abstract

Implementing endovascular stroke care often impedes neurologic assessment in patients who need sedation or general anesthesia. Cerebral near-infrared spectroscopy (NIRS) may help physicians monitor cerebral tissue viability, but data in hyperacute stroke patients receiving endovascular treatment are sparse. In this observational study, the NIRS index regional oxygen saturation (rSO2) was measured noninvasively before, during, and after endovascular therapy via bilateral forehead NIRS optodes. During the study period, 63 patients were monitored with NIRS; 43 qualified for analysis. Before recanalization, 10 distinct rSO2 decreases occurred in 11 patients with respect to time to intubation. During recanalization, two kinds of unilateral rSO2 changes occurred in the affected hemisphere: small peaks throughout the treatment (n=14, 32.6%) and sustained increases immediately after recanalization (n=2, 4.7%). Lower area under the curve 10% below baseline was associated with better reperfusion status (thrombolysis in cerebral infarction ≥ 2b, P=0.009). At the end of the intervention, lower interhemispheric rSO2 difference predicted death within 90 days (P=0.037). After the intervention, higher rSO2 variability predicted poor outcome (modified Rankin scale > 3, P=0.032). Our findings suggest that bi-channel rSO2-NIRS has potential for guiding neuroanesthesia and predicting outcome. To better monitor local revascularization, an improved stroke-specific set-up in future studies is necessary.

Figure 1

Flowchart of patients' screening and recruitment. IVT, intravenous thrombolysis; NIRS, near-infrared spectroscopy.

Figure 2

(A) Illustration of NIRS optode positioning at the border zone of the two territories of the middle and anterior cerebral arteries; the upper part shows six individual examples of time-to-peak magnetic resonance perfusion maps; the lower part is taken from a follow-up computed tomography scan—white arrow heads indicate NIRS optode positions. (B) Individual curve of one patient demonstrating the NIRS monitoring workflow, in principle including the predefined events for analysis. AUC_10%, area under the curve 10% below baseline; NIRS, near-infrared spectroscopy.

Figure 3

Individual examples of changes in regional oxygen saturation (rSO₂) are given: (A) before the intervention, a distinct bilateral decrease in rSO₂ with respect to time of intubation is followed by a recovery. (B) After the intervention, small transient increases in rSO₂ time with respect to time of extubation, and (C) relevant transient decreases in rSO₂ with respect to time of sudden loss of positive end-expiratory pressure are shown.

Figure 4

Individual examples of changes in regional oxygen saturation (rSO₂) during the intervention. The black line indicates the affected hemisphere: (A) throughout the whole intervention occurrence of small short peaks in rSO₂ predominantly in the affected hemisphere. (B) After successful reperfusion (time of recanalization indicated by the dotted vertical line), a sustained rSO₂ increase in the affected hemisphere was observed. (C) Pharmacological resuscitation during angiography: ‘N' indicates administration of norepinephrine; ‘A', amiodarone; ‘a', atropine; the area between the two dotted lines indicates a time of rSO₂ signal loss.

Figure 5

(A) Association of regional oxygen saturation (rSO₂)–area under the curve 10% below baseline (AUC_10%) with revascularization (measured by thrombolysis in cerebral infarction score (TICI)), (B) association of end-revascularization interhemispheric difference with death 90 days after stroke, (C) association of variability measure ASV_rSO2 after revascularization with poor functional outcome (modified Rankin scale 4 to 6). Asterisks (*) indicate P-value <0.05 in Mann–Whitney U-test. ASV_rSO2, average successive rSO₂ variability.