Safety of Peripheral Administration of 3% Hypertonic Saline in Critically Ill Patients: A Literature Review

Syndrome of Inappropriate Antidiuresis: From Pathophysiology to Management

Hyponatremia is the most common electrolyte disorder, affecting more than 15% of patients in the hospital. Syndrome of inappropriate antidiuresis (SIAD) is the most frequent cause of hypotonic hyponatremia, mediated by nonosmotic release of arginine vasopressin (AVP, previously known as antidiuretic hormone), which acts on the renal V2 receptors to promote water retention. There are a variety of underlying causes of SIAD, including malignancy, pulmonary pathology, and central nervous system pathology. In clinical practice, the etiology of hyponatremia is frequently multifactorial and the management approach may need to evolve during treatment of a single episode. It is therefore important to regularly reassess clinical status and biochemistry, while remaining alert to potential underlying etiological factors that may become more apparent during the course of treatment. In the absence of severe symptoms requiring urgent intervention, fluid restriction (FR) is widely endorsed as the first-line treatment for SIAD in current guidelines, but there is considerable controversy regarding second-line therapy in instances where FR is unsuccessful, which occurs in around half of cases. We review the epidemiology, pathophysiology, and differential diagnosis of SIAD, and summarize recent evidence for therapeutic options beyond FR, with a focus on tolvaptan, urea, and sodium-glucose cotransporter 2 inhibitors.

Safety of peripheral 3% hypertonic saline bolus administration for neurologic emergency

BACKGROUND/OBJECTIVE

Hypertonic sodium chloride (HTS) is used for emergent treatment of acute cerebral edema and other neurologic emergencies. Central access is not commonly available in emergent situations and 3% HTS is utilized peripherally. Many studies have shown the safety of its administration at rates up to 75 mL/h, but there is a lack of data to establish the safety of peripherally administered, rapid bolus dosing in emergent situations. The objective of this study is to describe the safety of rapid, peripherally administered (≥ 250 mL/h) 3% HTS for neurologic emergencies.

METHODS

This is a retrospective, cohort study including adult patients receiving 3% HTS via a peripheral IV site for elevated intracranial pressure, cerebral edema, or other neurological emergencies at a rate of at least 250 m/h between May 5, 2018 - September 30, 2021. Patients were excluded if they simultaneously received another hypertonic saline fluid. Baseline characteristics collected included HTS dose, rate and site of administration, indication for use and patient demographics. The primary safety outcome was incidence of extravasation and phlebitis within one hour of HTS administration.

RESULTS

There were 206 patients receiving 3% HTS who were screened, and 37 patients met inclusion criteria. The most common reason for exclusion was administration at a rate < 250 m/h. The median age was 60 (IQR 45, 72) with 51.4% being male. The most common indications for HTS were traumatic brain injury (45.9%) and intracranial hemorrhage (37.8%). The most common administration location was the emergency department (78.4%). The median IV-gauge (n = 29) was 18 (IQR 18, 20), with the most common placement site being antecubital (48.6%). The median dose of HTS was 250 mL (IQR 250, 350), with a median administration rate of 760 mL/h (IQR 500, 999). There were no episodes of extravasation or phlebitis noted.

CONCLUSIONS

Rapid, peripheral administration of 3% HTS boluses is a safe alternative for treatment of neurologic emergencies. Administration at rates up to 999 mL/h did not result in extravasation or phlebitis.

[Dysnatremia]

Changes in serum sodium concentrations are frequently encountered by anesthesiologists, are complex and are often inadequately treated. Feared consequences include neurological complications, such as cerebral hemorrhage, cerebral edema and coma. Dysnatremia is always accompanied disturbances in the water balance. Accordingly, these are routinely classified based on the tonicity; however, in the daily routine and especially in the acute setting, the volume status and extracellular volume are often difficult to assess. Severe symptomatic hyponatremia with impending cerebral edema is treated by administration of hypertonic saline solution. If the rise in serum sodium is too rapid, there is a risk of central pontine myelinolysis. In a second step, the cause of the hyponatremia can be investigated and the appropriate treatment can be initiated. In the case of hypernatremia, the etiology of the disorder must be clarified before treatment. The goal is to compensate for the water deficiency by correcting the cause, specific volume therapy and, if necessary, drug support. A slow and controlled compensation must be closely monitored in order to avoid neurological complications. An algorithm has been developed that provides an overview of the dysnatremias, aids with making the diagnosis and gives recommendations for treatment measures in the clinical routine.

Diagnosis and Management of Hyponatremia: A Review

IMPORTANCE

Hyponatremia is the most common electrolyte disorder and it affects approximately 5% of adults and 35% of hospitalized patients. Hyponatremia is defined by a serum sodium level of less than 135 mEq/L and most commonly results from water retention. Even mild hyponatremia is associated with increased hospital stay and mortality.

OBSERVATIONS

Symptoms and signs of hyponatremia range from mild and nonspecific (such as weakness or nausea) to severe and life-threatening (such as seizures or coma). Symptom severity depends on the rapidity of development, duration, and severity of hyponatremia. Mild chronic hyponatremia is associated with cognitive impairment, gait disturbances, and increased rates of falls and fractures. In a prospective study, patients with hyponatremia more frequently reported a history of falling compared with people with normal serum sodium levels (23.8% vs 16.4%, respectively; P < .01) and had a higher rate of new fractures over a mean follow-up of 7.4 years (23.3% vs 17.3%; P < .004). Hyponatremia is a secondary cause of osteoporosis. When evaluating patients, clinicians should categorize them according to their fluid volume status (hypovolemic hyponatremia, euvolemic hyponatremia, or hypervolemic hyponatremia). For most patients, the approach to managing hyponatremia should consist of treating the underlying cause. Urea and vaptans can be effective treatments for the syndrome of inappropriate antidiuresis and hyponatremia in patients with heart failure, but have adverse effects (eg, poor palatability and gastric intolerance with urea; and overly rapid correction of hyponatremia and increased thirst with vaptans). Severely symptomatic hyponatremia (with signs of somnolence, obtundation, coma, seizures, or cardiorespiratory distress) is a medical emergency. US and European guidelines recommend treating severely symptomatic hyponatremia with bolus hypertonic saline to reverse hyponatremic encephalopathy by increasing the serum sodium level by 4 mEq/L to 6 mEq/L within 1 to 2 hours but by no more than 10 mEq/L (correction limit) within the first 24 hours. This treatment approach exceeds the correction limit in about 4.5% to 28% of people. Overly rapid correction of chronic hyponatremia may cause osmotic demyelination, a rare but severe neurological condition, which can result in parkinsonism, quadriparesis, or even death.

CONCLUSIONS AND RELEVANCE

Hyponatremia affects approximately 5% of adults and 35% of patients who are hospitalized. Most patients should be managed by treating their underlying disease and according to whether they have hypovolemic, euvolemic, or hypervolemic hyponatremia. Urea and vaptans can be effective in managing the syndrome of inappropriate antidiuresis and hyponatremia in patients with heart failure; hypertonic saline is reserved for patients with severely symptomatic hyponatremia.

A Survey of Hospital Pharmacy Guidelines for the Administration of 3% Sodium Chloride in Children

Three percent sodium chloride (3% NaCl) is the treatment of choice for symptomatic hyponatremia. A barrier to the use of 3% NaCl is the perceived risk of both local infusion reactions and neurologic complications from overcorrection. We examine whether children’s hospital pharmacies have policies or practice guidelines for the administration of 3% NaCl and whether these pharmacies have restrictions on the administration of 3% NaCl in terms of rate, route, volume and setting. An Internet survey was distributed to the pharmacy directors of 43 children’s hospitals participating in the Children’s Hospital Association (CHA) network. The response rate was 65% (28/43). Ninety-three percent (26/28) of pharmacy directors reported a restriction for the administration of 3% NaCl, with 57% restricting its use through a peripheral vein or in a non-intensive care unit setting, 68% restricting the rate of administration and 54% restricting the volume of administration. Seventy-one percent (20/28) reported having written policy or practice guidelines. Only 32% of hospital pharmacies allowed 3% NaCl to be administered through a peripheral IV in a non-intensive care unit setting. The majority of children’s hospital pharmacies have restrictions on the administration of 3% NaCl. These restrictions could prevent the timely administration of 3% NaCl in children with symptomatic hyponatremia.

Hypertonic Saline for Hyponatremia: Meeting Goals and Avoiding Harm

Hypertonic saline has been used for the treatment of hyponatremia for nearly a century. There is now general consensus that hypertonic saline should be used in patients with hyponatremia associated with moderate or severe symptoms to prevent neurological complications. However, much less agreement exists among experts regarding other aspects of its use. Should hypertonic saline be administered as a bolus injection or continuous infusion? What is the appropriate dose? Is a central venous line necessary? Should desmopressin be used concomitantly and for how long? This article considers these important questions, briefly explores the historical origins of hypertonic saline use for hyponatremia, and reviews recent evidence behind its indications, dosing, administration modality and route, combined use with desmopressin to prevent rapid correction of serum sodium, and other considerations such as the need and degree for fluid restriction. The authors conclude by offering some practical recommendations for the use of hypertonic saline.