Use of Conivaptan (Vaprisol) for hyponatremic neuro-ICU patients

Hyponatremia is common in neurocritical care and is associated with poor outcome, but the optimal treatment is not known. We wished to test the hypothesis that for neurocritical care patients with severe hyponatremia (Na < 130 mmol/l) or hyponatremia (Na < 135 mmol/l) with depressed Glasgow Coma Scale (GCS) that conivaptan use would lead to increased serum sodium compared to usual care.

We prospectively screened 249 neurocritical care patients with hyponatremia for a prospective, randomized pilot (goal N = 20) trial. Study interventions were usual care, or usual care plus conivaptan 20 mg IV as a bolus followed by 20 mg IV over 24 h, the lower FDA-approved dose. Patients were prospectively followed for changes in serum and urine electrolytes and clinical examinations with a blinded examiner. This study is registered at www.clinicaltrials.gov (NCT00727090).

Despite the prevalence of hyponatremia, recruitment was difficult, and the study was terminated after six patients were enrolled, three in each group. Most hyponatremia in screened but non-randomized patients was transient or not associated with depressed GCS. Conivaptan led to higher serum sodium compared to usual care. The change in serum sodium from baseline, the pre-specified endpoint, was significantly different between groups at six (7.0 +/- 1.7 vs. -0.6 +/- 2.1 mmol/l, P = 0.008), 24 (9.7 +/- 3.2 vs. 0 +/- 1.0 mmol/l), and 36 h (8.0 +/- 5.6 vs. -1.7 +/- 2.1 mmol/l, P = 0.05). There were no apparent differences in clinical examination as a result of treatment. Adverse events were similar, and all randomized patients completed the protocol.

Despite an inclusive protocol, most patients were not candidates for conivaptan therapy for hyponatremia. The role of conivaptan in the Neuro-ICU remains to be defined.