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HWN Suggests

Episode 60: Emergency Management of Hyponatremia

In the event of a seizure, coma or suspected cerebral herniation as a result of hyponatremia, IV 3% hypertonic saline should be administered as soon as possible according to the following guide:

• Administer 3% hypertonic saline 100-150cc IV over 5-10min
• If the patient does not improve clinically after the first bolus, repeat a second bolus of hypertonic saline
• Stop all fluids after the second bolus of hypertonic saline to avoid raising the serum sodium any further

What if hypertonic saline is not readily available?

Administer one ampule of Sodium Bicarbonate IV over 5min

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  How to give a bolus of hypertonic fluid:

A typical dose is two ampules (100ml) of hypertonic bicarbonate (equivalent to giving ~200 ml of 3% saline, which will raise the serum sodium by ~3 mM). For smaller patients, 1 or 1.5 ampules (50-75 ml) might be more appropriate (depending also on the clinical context and the urgency of increasing the sodium). Ampules of bicarbonate should generally be infused slowly (e.g. each one over 5 minutes). Bicarbonate is contraindicated in patients with metabolic alkalosis, which would be exacerbated by the bicarbonate. 3% saline may be provided in a dose of 2 ml/kg body weight (e.g., ~150 ml). This is the traditional therapy for hyponatremia. The main drawback of 3% saline is that it often takes a long time to receive from the pharmacy. Please note that 3% saline is safe to administer through a peripheral line. 3% saline does NOT require placement of a central line.

 Trick of the Trade: Sodium Bicarbonate for Acute Symptomatic Hyponatremia

Generally, 100 – 150 mL boluses of 3% sodium chloride are used for the treatment of severe symptomatic hyponatremia. However, it can take some time for these to be prepared by pharmacy. Sodium bicarbonate ampules can be found in crash carts, can be accessed and administered more quickly than 3% sodium chloride, and provide comparable hypertonicity.

Articles of Interest

Severe Hyponatremia

Hypertonic saline is not only indicated for seizures, coma, suspected cerebral herniation or focal neurological deficits as noted above. Keep in mind the indication for 3% also extends to altered mental status and can present w/ simple confusion or even “just acting off” from baseline. Do keep in mind the acuteness of the neurologic status is also imperative to determining the need of hypertonic. More acute symptoms = higher likelihood of needing 3%.

Tips to Assess Rapid Onset of Hyponatremia to Prevent Overcorrection and Diagnose Underlying Cause

1. Treat neurologic emergencies related to hyponatremia. In the event of a seizure, coma, or suspected cerebral herniation as a result of hyponatremia, 3% hypertonic saline 150 mL IV over five to 10 minutes should be administered as soon as possible. If the patient does not improve clinically after the first bolus, repeat a second bolus of hypertonic saline. It is important to stop all fluids after the second bolus to avoid raising the serum sodium any further. If hypertonic saline is not readily available, administer one ampule of sodium bicarbonate over five minutes.

When and how to treat hyponatremia in the ED

Severely symptomatic. IV bolus 150 ml 3% hypertonic over 20 min, check serum sodium. Repeat IV bolus 150 ml 3% hypertonic over 20 min, check serum sodium.

"The Hyponatremia.ˮ A Real Masquerader in Emergency Medicine

The Hyponatremia is the most common electrolyte disorder, occurring in up to 30% among hospitalized patients and has been associated with increased mortality. Hyponatremia occurs in a broad spectrum of patients who are asymptomatic or critically ill.

Acute Dysnatremias - a dangerous and overlooked clinical problem

Dysnatremias are common electrolyte disturbances with significant morbidity and mortality. In chronic dysnatremias a slow correction rate (<10 mmol/L/24 h) is indicated to avoid neurological complications. In acute dysnatremias (occurring <48 h) a rapid correction rate may be indicated. Most guidelines do not differ between acute and chronic dysnatremias.

Critical Hyponatremia: Pearls and Pitfalls

If the patient is significantly altered or seizing with serum sodium concentration < 130 mEq/L, administer 3% hypertonic saline 100 cc IV over 10 min peripherally or centrally (can substitute for an ampule of bicarbonate). Up to three boluses of hypertonic saline may be administered over a span of 30 minutes, symptom resolution is the target. If symptom resolution is not achieved after bolus administration, patient may be placed on a hypertonic infusion with a target of 4-6 mEq/L increase in the first six hours (use a weight-based formula). Check serum sodium concentrations hourly, expect sodium concentrations to rise 1-2 mEq per bolus. Once symptom resolution is achieved, transition to continuous isotonic intravenous infusion with a target of 4- 6 mEq/L increase in the first six hours (use a weight-based formula). Consider concurrent administration of desmopressin (1-2mcg IV q8 hours) if the patient examines as hypovolemic.

Hyponatremia – EMC 60: Emergency Management of Hyponatremia

In addition to being extremely prevalent, hyponatremia is an independent predictor of MORTALITY. There is a clear, linear relationship between serum sodium <135 mmol/L at the time of admission to hospital and IN HOSPITAL mortality. Efforts to reverse hyponatremia can also be dangerous for the patient. Under correction of serum sodium can lead to the development of cerebral edema whereas rapid over-correction of serum sodium can put patients at risk for Osmotic Demyelination Syndrome (ODS)- formerly known as Central Pontine Myelinolysis.

The SALSA Study: Hypertonic Saline to Treat Hyponatremia

This randomized clinical trial found that both RIB and SIC therapies of hypertonic saline for treating hyponatremia were effective and safe, with no difference in the overcorrection risk. However, RIB had a lower incidence of therapeutic relowering treatment and tended to have a better efficacy in achieving sNa within 1 hour than SCI. RIB could be suggested as the preferred treatment of symptomatic hyponatremia, which is consistent with the current consensus guidelines.

The SALSA Trial: Symptomatic Hyponatremia and Hypertonic Saline

Under-correction could lead to cerebral edema, whereas overcorrection could result in osmotic demyelination syndrome (ODS). The current recommendation is to use hypertonic saline in small, fixed, intermittent boluses. This approach avoids rapid partial correction of serum sodium, limits risk of overcorrection, and doesn’t require complex calculations. Slow continuous infusions on the other hand, require complex calculations to adjust hypertonic saline infusions to a rate of correction over time based on the rate of serum sodium correction.

Resources

BC Emergency Medicine Network

100-150 mL bolus of 3% hypertonic saline over 10-20 minutes. This can be repeated up to 2 times until symptoms resolve and or sodium is corrected 4-6mEq/L. Re-check sodium 1 hour following bolus and infusion initiation and sodium every 4 hours.