Can blood tests tell me if I will get delayed cerebral ischemia?

Delayed cerebral ischemia (DCI) is a serious complication after a subarachnoid hemorrhage (aSAH). Doctors currently struggle to predict who will get it early on. New research shows that blood tests can find specific chemical patterns in the blood that differ between patients who develop DCI and those who do not. These patterns involve specific metabolites, which are small molecules produced by the body or gut bacteria.

What the research says

One study found that analyzing the full profile of chemicals in the blood within 24 hours of admission could clearly separate patients who would develop DCI from those who would not. This approach identified 110 different chemical changes, including increases in sphinganine and decreases in other markers, which helped distinguish the two groups with high accuracy ¹.

Another study looked specifically at chemicals made by gut bacteria. It found that patients with poor outcomes had lower levels of short-chain fatty acids like propionic and isovaleric acids on the first day after the bleed. They also had persistently lower levels of tryptophan and indole-3-propionic acid (IPA) at both day 1 and day 9 ².

Researchers are now using computer models to combine these blood test results with other patient data to make better predictions. Studies comparing different computer methods found that ensemble models, which use many algorithms together, performed best. These models achieved an accuracy score (AUC) between 0.80 and 0.85, which is considered good for medical prediction tools ³.

What to ask your doctor

• Are there any blood tests available at your center that look for specific chemical patterns to predict DCI?
• How often should I get blood drawn to track these metabolite levels after my surgery or bleed?
• Can my doctor explain what my specific blood test results mean for my risk of developing DCI?
• What other factors besides blood tests does my doctor consider when assessing my risk for DCI?