Continuous Near-Infrared Spectroscopy as a Real-Time Monitor of Intravenous Thrombolysis in Acute Ischaemic Stroke: A Prospective Observational Emergency Department Study

Background. Intravenous (IV) thrombolysis is the standard of care for acute ischaemic stroke (AIS), yet there is still no objective bedside tool for monitoring the brain continuously during the infusion. Near-infrared spectroscopy (NIRS) provides non-invasive, continuous measurement of regional cerebral oxygen saturation (rSO2). We evaluated whether bilateral frontal NIRS, and in particular the absolute interhemispheric difference in rSO2 (ΔNIRS), tracks the clinical trajectory of patients receiving IV alteplase in the emergency department (ED). Methods. A prospective observational cohort study was conducted in the ED of a tertiary university hospital. Consecutive adults receiving IV alteplase for AIS were screened, and those enrolled underwent continuous bilateral frontal NIRS monitoring. Bilateral rSO2, ΔNIRS, vital signs, Glasgow Coma Scale (GCS) and National Institutes of Health Stroke Scale (NIHSS) were recorded at baseline and at 0, 15, 30, 45, 60 and 120 min after the start of the infusion. Patients were classified by clinical trajectory during monitoring as improvement, no change, or deterioration. Results. Forty-one patients were analyzed (26 female, 63.4%; mean age 73.6 ± 14.8 years); 15 (36.6%) improved, 21 (51.2%) showed no change and 5 (12.2%) deteriorated. In the whole cohort, absolute rSO2 rose only slightly in the affected hemisphere and did not change in the unaffected hemisphere. However, affected-hemisphere rSO2 rose significantly in the improvement group (median 59 to 67; p = 0.001) and fell significantly in the deterioration group (p = 0.015). ΔNIRS narrowed from a median of 4 (IQR 3–9) at baseline to 1 (IQR 0–5) at 120 min in the improvement group (p = 0.034) and did not change significantly in the other groups. The two patients with acute complications desaturated bilaterally. NIHSS correlated strongly and inversely with GCS at every time point (ρ = −0.74 to −0.84; all p < 0.001). Conclusions. During IV thrombolysis in the ED, continuous bilateral frontal NIRS tracked the clinical trajectory. Because recanalisation and reperfusion were not assessed independently, what NIRS paralleled was the clinical course, not reperfusion itself. These hypothesis-generating findings warrant larger studies that validate ΔNIRS against perfusion or vascular imaging.