Transcranial regional cerebral oxygen desaturation predicts delayed cerebral ischaemia and poor outcomes after subarachnoid haemorrhage: a correlational study.

Objectives: To examine the relationship between regional cerebral oxygen saturation (rSO2), delayed cerebral ischaemia (DCI), and outcomes after aneurysmal subarachnoid haemorrhage (aSAH).

Research Methodology: Subjects (n = 163) with aSAH, age 21-75 years, and Fisher grade >1 were included in the study. Continuous rSO2 monitoring was performed for 5-10 days after injury using near-infrared spectroscopy with sensors over the frontal/temporal cortex. rSO2<50 indicated desaturation. DCI was defined as neurological deterioration due to impaired cerebral blood flow. Three- and 12-month functional outcomes were assessed by the modified Rankin scale (MRS) as good (0-3) and poor (4-6).

Results: DCI occurred in 57% of patients; of these 66% had rSO2<50. Overall, 56% had rSO2<50 on either side, 21% and 16% had poor MRS at 3 and 12 months. Subjects with rSO2 <50 were 3.25 times more likely to have DCI compared to those with rSO2 >50 (OR 3.25, 95%CI 1.58-6.69), positive predictive value (PPV) = 70%. Subjects with rSO2 <50 were 2.7 times more likely to have poor 3-month MRS compared to those with rSO2 >50 (OR 2.7, 95%CI 1.1-7.2), PPV = 70%.

Conclusions: These results suggest that NIRS has the potential for detecting DCI after aSAH. This potential needs to be further explored in a larger prospective study.