Patients with severe subarachnoid hemorrhage (SAH) may present platelet and coagulation dysfunctions immediately after the stroke on admission at the hospital, and persisting up to 3-4 weeks after the onset. This study aimed to investigate the platelet function as assessed by impedance agregometry (ROTEM Platelet) and platelet adhesion (PFA), and the coagulation profile as assessed by ROTEM, over three evolutive times.

Patients with severe subarachnoid hemorrhage (SAH) present platelet and coagulation dysfunctions immediately after the stroke, at least two weeks after the onset of SAH. These alterations have been implicated in the presentation of delayed cerebral ischemia (DCI), vasospasm, deep vein thrombosis (DVT) and long-term neurological deterioration. The temporal presentation of the platelet dysfunction and coagulation has not consistently been established, nor have they been assessed with tests for specific platelet receptors. Objective. Primary: To document the platelet function and coagulation, in constant and fixed periods after the stroke onset, in patients with severe SAH, Hunt and Hess 4-5, Fisher 4. Secondary: Relationship between the patterns of hemostasis and coagulation and the presence of vasospasm, DCI and DVT. Method. Prospective, cohort study that will include (calculated sample size) 50 patients with severe SAH, recruited in the first 6 hours after the onset of symptoms. Twenty healthy volunteers (already recruited) will constitute the control group. Platelet function will be studied by platelet count, von Willebrand factor level, platelet function assay (PFA-100), and platelet ROTEM for specific stimulation of platelet receptors (ARATEM, ADPTEM, TRAPTEM). The coagulation will be investigated by conventional coagulation study, ROTEM EXTEM, ROTEM FIBTEM and factor XIII. In the group with SAH, blood samples will be drawn into the first 6 hours after the onset of symptoms (t0), in the period of 8 - 10 days after the stroke (t1) - period of maximum incidence of TBI and DVT - and 14- 16 days after the stroke (t2) in order to evaluate the late degree of coagulation alterations. Baseline values (t0) will be compared between subjects with HSA and the control group (intersubjects comparisons.). On the other hand, significant changes of the hemostasis and coagulation values among the times t0, t1 and t2 in the HAS group, will be also investigated (intra-subjects comparisons). Additionally, the relationship between the hemostasis and coagulation values evaluated at any of the specified time and the clinical outcome, as assessed by the presence of DCI, vasospasm, DVT or neurological deterioration at 3 months of follow-up (mRs> 3), will be also investigated

Inclusion Criteria:

• Consecutive patients with severe subarachnoid hemorrhage (Hunt and Hess 4-5, Fisher 3-4) will be included initially in the first 6 hours after the onset of symptoms.

Exclusion Criteria:

1. Patient with known coagulopathy or with ingestion of antiplatelet drugs or anticoagulants in the 15 days prior to the presentation of symptoms.
2. Patients in whom there is no confirmed arteriovenous malformation.
3. The patient or authorized family member denies informed consent.
4. High risk of imminent death, evaluated by the doctor in charge of the patient.
5. Hemoglobin <100 g / L and / or platelet count <100,000 microL

Patients with severe subarachnoid hemorrhage (Hunt and Hess 4-5, Fisher 3-4) in the first 6 hours after the onset of symptoms