Introduction: Vaptans are a family of vasopressin receptor antagonists used to treat hyponatremia associated with heart failure, cirrhosis and SIADH. Here we investigate the utility of tolvaptan, an orally administered agent, in patients with subarachnoid hemorrhage and hyponatremia.
Methods: Patients who developed hyponatremia (serum sodium = 130mMol/L) within 14 days of a ruptured intracranial aneurysm and who were managed in an ICU were included in the study. Tolvaptan was initially dosed at 15mg per day for a total of 3 doses. The dose was increased by 15mg daily (to a maximum dose of 45mg) if serum sodium did not normalize (135mMol/L or greater). IV fluids (0.9% saline) were administered at a rate of 100ml/hr during drug treatment.
Results: Seven patients met inclusion criteria. The average serum sodium level of patients prior to administration of tolvaptan was 129 mMol/L. The drug was administered for an average of 4.1 days. Two of the eight patients required at least one dosage increase due to lack of response. All patients had an increase in sodium levels with an average daily correction of 5.9mMol/L. The average peak sodium concentration was 140.5 mMol/L and was reached in an average of 2.1 days. Compared to pre-drug administration, patients demonstrated a 172% increase in urine output in comparison to a 168% increase in fluid intake. The average sodium concentration 24 hours after discontinuing medication was 137.5mMol/L. Of the 6 patients whose hospital stay was greater than 24 hours after final dose, four were noted to have recurrent hyponatremia.
Conclusions: Tolvaptan appears to adequately correct hyponatremia associated with subarachnoid hemorrhage, however the effect may not be durable. As expected, urinary outputs were increased by drug administration but euvolemia was maintained via intravenous and oral fluids. Further investigation is required to assess the safety and utility of vaptans in the setting of subarachnoid hemorrhage.
Patient Care: Oral agents for management of hyponatremia can allow for non-ICU level of care of patients with hyponatremia associated with subarachnoid hemorrhage; this can decrease ICU related complications and decrease the cost of hospitalization in this patient population.
Learning Objectives: By the conclusion of this session, participants should be able to 1) describe the complexities of treating hyponatremia in the setting of subarachnoid hemorrhage. 2) Discuss the utility of vaptans in the treatment of SAH induced hyponatremia.