Osmotic Therapy for Patients With Severe Subarachnoid Hemorrhage

Inclusion Criteria: * ①age ≥18； ②aneurysmal subarachnoid hemorrhage; ③Hunt-Hess 3-5级 Exclusion Criteria: * previous cranial decompression surgery, cerebrospinal fluid leakage or drainage, * bilateral pupils fixed or dilated, * hemodynamic instability, * hemoglobin \< 8g / L, * serum osmolality \> 320 mOsm / L, ⑥ combined with severe organ dysfunction (cardiac, pulmonary, hepatic, renal and so on); ⑦ serious electrolyte disorders (serum sodium concentration \<125 mmol / L or \>170 mmol / L), and difficult to correct within limited time; ⑧ serious acid-base balance disorders, and difficult to correct within limited time; ⑨ use of mannitol or HSS within previous six hours; ⑩ being pregnant.