Effects of M101-an extracellular hemoglobin-applied during cardiopulmonary resuscitation: An experimental rodent study.

During and immediately after cardiac arrest, cerebral oxygen delivery is impaired mainly by microthrombi and cerebral vasoconstriction. This may narrow capillaries so much that it might impede the flow of red blood cells and thus oxygen transport. The aim of this proof-of-concept study was to evaluate the effect of M101, an extracellular hemoglobin-based oxygen carrier (Hemarina SA, Morlaix, France) derived from Arenicola marina, applied during cardiac arrest in a rodent model, on markers of brain inflammation, brain damage and regional cerebral oxygen saturation.27 Wistar rats subjected to 6 min of asystolic cardiac arrest were infused M101 (300 mg/kg) or placebo (NaCl 0.9%) concomitantly with start of cardiopulmonary resuscitation. Brain oxygenation and five biomarkers of inflammation and brain damage (from blood, cerebrospinal fluid, and homogenates from four brain regions) were measured 8 hours after return of spontaneous circulation. In these 21 different measurements, M101-treated animals were not significantly different from controls except for phospho-tau (p-tau) only in single cerebellum regions (p = 0.048; ANOVA of all brain regions: p = 0.004). Arterial blood pressure increased significantly only at 4-8 min after return of spontaneous circulation (p < 0.001) and acidosis decreased (p = 0.009).While M101 applied during cardiac arrest did not significantly change inflammation or brain oxygenation, the data suggest cerebral damage reduction due to hypoxic brain injury, measured by p-tau. Global burden of ischemia appeared reduced since acidosis was less severe. Whether post-cardiac arrest infusion of M101 improves brain oxygenation is unknown and needs to be investigated.