The patients with severe hypernatremia who received conventional treatment are often undertreated. Continuous venovenous hemofiltration (CVVH) can effectively remove solute or water from circulation system. Several case reports demonstrated that CVVH could effectively decrease serum sodium concentration of the patients with severe hypernatremia. The use of CVVH for acute severe hypernatremia in critically ill patients could improve patient survival by effectively decreasing the serum sodium concentration to a normal level.

Date collection:

1. Demographic (gender, age, race, weight, history of drug allergy, complicating diseases, drug combination and combination therapy)
2. CVVH treatment (time, blood vessel, blood flow, replacement fluid flow, the type and dose of anticoagulant, limited to the test group)
3. Vital signs (blood pressure, heart rate, respiratory frequency, body temperature)
4. Severity of disease
5. General treatment (Vasoactive drugs, mechanical ventilation, diuretic, steroid hormones) 6.24 hours input 7.24 hour output

8.Daily sodium intake 9.Adverse events were confirmed 10.Laboratory date: Routine blood test Blood biochemical Blood gas analysis Blood electrolyte Plasma osmotic pressure Urine osmotic pressure Plasma osmotic pressure Urinary electrolyte excretion fraction

Inclusion Criteria:

1. Age≥18 years
2. Acute severe hypernatremia(increasing of serum sodium levels from normal levels to ≥160 mmol/L within 48 hours)
3. ICU patients

Exclusion Criteria:

1. Hypovolemic hypernatremia fractional excretion of sodium <0.5% and Urea/Creatinine >40 receiving diuretics: Urea/Creatinine >40, No edema.
2. Acute kidney injure network III
3. End-stage renal disease Hemodialysis or peritoneal dialysis
4. K+>6.5mmol/L The drug is difficult to treat hyperkalemia
5. Hydrogen ion concentration<7.2 The drug is difficult to treat metabolic acidosis
6. Acute pulmonary edema
7. Systolic blood pressure <90 mmHg vasoactive drugs in the treatment of systolic blood pressure less than 90 mmHg
8. The heparin or low molecular allergic patients
9. HIV positive patients
10. Pregnant women or lactational pregnancy women
11. Suspected tuberculosis patients