Response to a bolus of conivaptan in patients with acute hyponatremia after brain injury

Conivaptan for the Reduction of Cerebral Edema in Intracerebral Hemorrhage: A Safety and Tolerability Study

BACKGROUND

Perihematomal edema (PHE) growth in intracranial hemorrhage (ICH) is a biomarker for worse outcomes. Although the management of PHE is potentially beneficial for ICH patients, there is currently no proven clinical therapy that both reduces PHE and improves outcomes in this population.

OBJECTIVE

To examine the safety and tolerability of conivaptan, a non-peptide vasopressin (AVP) receptor antagonist, for the management of PHE in ICH patients.

METHODS

We performed a single-center, open-label, phase I study in seven patients with ICH at risk for developing PHE. Conivaptan (20 mg) was administered every 12 h for 2 days, along with the standard ICH management. Electrolyte levels, renal and cardiac function, and vital signs were monitored throughout treatment. Neurological status, ICH, and PHE volumes were assessed at study baseline, 24 h, 72 h, and 7 days from the first conivaptan administration, as well as at the 3-month follow-up.

RESULTS

Conivaptan was well tolerated in our patients. We observed the expected increase in sodium levels following conivaptan administration (p = 0.01), with no change in cardiac or renal function. All patients survived to follow-up, and adverse event rates were comparable with those of the neurocritical care unit overall.

CONCLUSIONS

These data indicate that conivaptan can be safely administered to ICH patients and support further clinical investigation into the efficacy of this drug for ICH treatment.

CLINICAL TRIAL REGISTRATION

clinicaltrials.gov; NCT03000283, 22 December 2016.

Does Vasopressin Exacerbate Cerebral Edema in Patients with Severe Traumatic Brain Injury?

Arginine vasopressin (AVP) is often used as an alternative pressor to catecholamines (CATs). However, unlike CATs, AVP is a powerful antidiuretic that could promote edema. We tested the hypothesis that AVP promoted cerebral edema and/or increased requirements for osmotherapy, relative to those who received CATs, for cerebral perfusion pressure (CPP) management after traumatic brain injury (TBI). This is a retrospective review of 286 consecutive TBI patients with intracranial pressure monitoring at a single institution from September 2008 to January 2015. Cerebral edema was quantitated using CT attenuation in prespecified areas of gray and white matter. Results: To maintain CPP >60 mm Hg, 205 patients required no vasopressors, 41 received a single CAT, 12 received AVP, and 28 required both. Those who required no pressors were generally less injured; required less hyperosmolar therapy and less total fluid; and had lower plasma Na, lower intracranial pressure, less edema, and lower mortality (all P < 0.05). Edema; daily mean, minimum, and maximum Na levels; and mortality were similar with AVP versus CATs, but the daily requirement of mannitol and 3 per cent NaCl were reduced by 45 and 35 per cent (both P < 0.05). In patients with TBI who required CPP therapy, AVP reduced the requirements for hyperosmolar therapy and did not delay resolution or increase cerebral edema compared with CATs.

Effectiveness and Tolerability of Conivaptan and Tolvaptan for the Treatment of Hyponatremia in Neurocritically Ill Patients

STUDY OBJECTIVE

To describe the effectiveness and tolerability of conivaptan and tolvaptan for the correction of hyponatremia in neurocritically ill patients.

DESIGN

Retrospective cohort study.

SETTING

Neurointensive care units at two academic medical centers.

PATIENTS

Thirty-six adults admitted to the neurocritical care unit who received at least one dose of conivaptan (5 patients) or tolvaptan (31 patients) between June 2012 and May 2013.

MEASUREMENTS AND MAIN RESULTS

A single oral dose or intravenous bolus was administered to 23 (74%) patients who received tolvaptan and 2 (40%) patients who received conivaptan, respectively. The mean maximal increase in serum sodium level at 24 hours following the last dose compared with baseline was 5.2 mEq/L for conivaptan (p=0.05) and 7.9 mEq/L for tolvaptan (p<0.001). The mean ± SD maximal increases in serum sodium level at 48, 72, and 96 hours following the last dose of vaptan therapy compared with baseline were 5.5 ± 2.2 mEq/L (p=0.01), 5.6 ± 2.0 mEq/L (p=0.005), and 4.8 ± 2.2 mEq/L (p=0.03), respectively. Sodium overcorrection occurred in six patients (19%) receiving tolvaptan and none of the patients receiving conivaptan. Hypotension occurred in 20% of patients receiving conivaptan and 52% of patients receiving tolvaptan, whereas hypokalemia was observed in 40% of patients receiving conivaptan.

CONCLUSION

Use of vaptans in neurocritically ill patients led to a significant increase in serum sodium level at 24 hours after the last dose, which was sustained for 96 hours, with the majority of patients receiving a single dose. Risk of sodium overcorrection was high and necessitates appropriate patient selection and frequent monitoring.

Hyponatremia in the intensive care unit: How to avoid a Zugzwang situation?

Hyponatremia is a common electrolyte derangement in the setting of the intensive care unit. Life-threatening neurological complications may arise not only in case of a severe (<120 mmol/L) and acute fall of plasma sodium levels, but may also stem from overly rapid correction of hyponatremia. Additionally, even mild hyponatremia carries a poor short-term and long-term prognosis across a wide range of conditions. Its multifaceted and intricate physiopathology may seem deterring at first glance, yet a careful multi-step diagnostic approach may easily unravel the underlying mechanisms and enable physicians to adopt the adequate measures at the patient’s bedside. Unless hyponatremia is associated with obvious extracellular fluid volume increase such as in heart failure or cirrhosis, hypertonic saline therapy is the cornerstone of the therapeutic of profound or severely symptomatic hyponatremia. When overcorrection of hyponatremia occurs, recent data indicate that re-lowering of plasma sodium levels through the infusion of hypotonic fluids and the cautious use of desmopressin acetate represent a reasonable strategy. New therapeutic options have recently emerged, foremost among these being vaptans, but their use in the setting of the intensive care unit remains to be clarified.

Hyponatremia in the neurocritical care patient: An approach based on current evidence

In the neurocritical care setting, hyponatremia is the commonest electrolyte disorder, which is associated with significant morbimortality. Cerebral salt wasting and syndrome of inappropriate antidiuretic hormone have been classically described as the 2 most frequent entities responsible of hyponatremia in neurocritical care patients. Nevertheless, to distinguish between both syndromes is usually difficult and useless as volume status is difficult to be determined, underlying pathophysiological mechanisms are still not fully understood, fluid restriction is usually contraindicated in these patients, and the first option in the therapeutic strategy is always the same: 3% hypertonic saline solution. Therefore, we definitively agree with the current concept of "cerebral salt wasting", which means that whatever is the etiology of hyponatremia, initially in neurocritical care patients the treatment will be the same: hypertonic saline solution.

Neurosurgical Hyponatremia

Hyponatremia is a frequent electrolyte imbalance in hospital inpatients. Acute onset hyponatremia is particularly common in patients who have undergone any type of brain insult, including traumatic brain injury, subarachnoid hemorrhage and brain tumors, and is a frequent complication of intracranial procedures. Acute hyponatremia is more clinically dangerous than chronic hyponatremia, as it creates an osmotic gradient between the brain and the plasma, which promotes the movement of water from the plasma into brain cells, causing cerebral edema and neurological compromise. Unless acute hyponatremia is corrected promptly and effectively, cerebral edema may manifest through impaired consciousness level, seizures, elevated intracranial pressure, and, potentially, death due to cerebral herniation. The pathophysiology of hyponatremia in neurotrauma is multifactorial, but most cases appear to be due to the syndrome of inappropriate antidiuretic hormone secretion (SIADH). Classical treatment of SIADH with fluid restriction is frequently ineffective, and in some circumstances, such as following subarachnoid hemorrhage, contraindicated. However, the recently developed vasopressin receptor antagonist class of drugs provides a very useful tool in the management of neurosurgical SIADH. In this review, we summarize the existing literature on the clinical features, causes, and management of hyponatremia in the neurosurgical patient.

Conivaptan for treatment of hyponatremia in neurologic and neurosurgical adults

OBJECTIVE

To review the literature evaluating the clinical safety and efficacy of conivaptan in the management of hyponatremia in a neurologic and neuro-surgical adult patient population.

DATA SOURCES

A literature search was conducted using MEDLINE, EMBASE, PubMed, and the Cochrane Central Register of Controlled Trials (1966-May 2013). Search limits were English, human, and adult using the terms vasopressin receptor antagonist, conivaptan, tolvaptan, lixivaptan, neurology, neurological disorder, neurosurgery, neurointensive care, and neurocritical care.

STUDY SELECTION AND DATA EXTRACTION

All case reports, case series, and clinical trials investigating the use of conivaptan in neurosurgical patients were included.

DATA SYNTHESIS

Seven reports were identified using conivaptan as monotherapy or adjunctive treatment for hyponatremia in a neurosurgical patient population. One study was a prospective, randomized, controlled trial, while 6 reports were case reports or case series. The prospective randomized trial found a significant increase in serum sodium concentration over baseline with a conivaptan 20-mg intravenous bolus dose followed by a 20-mg/day continuous infusion for 24 hours compared to "usual care" at 6 hours (7.0 ± 1.7 vs -0.6 ± 2.1 mEq/L, respectively; p = 0.008) and 36 hours (8.0 ± 5.6 vs -1.7 ± 2.1 mEq/L, respectively; p = 0.05) after treatment. One case series found that the mean serum sodium remained significantly increased from baseline up to 72 hours (5.12 ± 4.0 mEq/L; p < 0.001) after a single conivaptan 20-mg intravenous bolus dose. All reports demonstrated clinical effectiveness of conivaptan in significantly increasing serum sodium concentrations following administration compared to baseline. However, the clinical significance of this finding remains debatable since some of these patients remained hyponatremic.

CONCLUSIONS

Overall, conivaptan is a promising and well-tolerated agent for the management of hyponatremia in neurologic and neurosurgical patients. However, its use should be limited to patients in whom conventional therapies fail or as adjunctive therapy.