Critical disorders such as severe burns, trauma, sepsis, brain damage, and heart failure lead to disturbances in fluid and electrolyte homeostasis.

Electrolyte and fluid abnormalities may lead to significant adverse clinical effects like:

● Cardiac arrest and arrhythmias.

● Skeletal muscle weakness.

● Respiratory muscle weakness.

● Respiratory failure.

● Convulsions.

● Delirium.

Intravenous infusions of electrolytes must be administered with free-flow protected infusion devices (i.e., infusion pump).

Patients need frequent evaluation and monitoring of their electrolyte and fluid homeostasis during replacement therapy.

The electrolyte replacement protocol of Calcium gluconate, Magnesium sulfate, Potassium chloride, may be ordered individually or in combination.

Available intravenous (IV) products: Potassium chloride (KCl) contains potassium 2 mmol/mL.

The underlying cause of hypokalemia should be identified and corrected.

Check sodium level (sodium status can influence potassium homeostasis).

Standard concentration:

● 20 mmol/250 mL NS for peripheral line. (Maximum concentration 10 mmol/100 mL).

● 20 mmol/100 mL NS for Central line (Maximum concentration 40 mmol/100 mL).

All Potassium infusions must be administered via infusion pumps.

● Peripheral access: infuse at a rate of 10 mmol /hr.

● Central access: infuse at a rate of 20 mmol/hr with continuous ECG monitoring.

If creatinine clearance (CrCL) <30 mL/min, reduce the dose by 50%.

Magnesium should be repleted as well because failure to treat this will make it difficult to fix hypokalemia.

Current Serum

Potassium Level

Administration

Through

Central Venous Catheter

Administration

Through

Peripheral Vein

Recheck

Level

< 2.6 mmol/L

100 mmol KCl

KCl 10 mmol X 10 doses

2-hours after replacement and adjust treatment accordingly.

2.6-2.9 mmol/L

80 mmol KCl

KCl 10 mmol X 8 doses.

2-hours after replacement and adjust treatment accordingly.

3.0-3.2 mmol/L

60 mmol KCl

KCl 10 mmol X 6 doses.

2-hours after replacement and adjust treatment accordingly.

3.3-3.5 mmol/L

40 mmol KCl

KCl 10 mmol X 4 doses.

2-hours after replacement and adjust treatment accordingly.

3.6-3.9 mmol/L

20 mmol KCl

KCl 10 mmol X 2 doses.

With routine morning labs next day.

Current serum potassium level

Oral KCl replacement

3.3-3.5 mmol/L

40 mEq x 1 dose.

3.0-3.2 mmol/L

40 mEq x 1 dose then an Additional 20 mEq in 2hours x1 dose.

2.6-2.9 mmol/L

Give 40 mEq x 1 dose then an Additional 40 mEq in 2 hours.

< 2.6 mmol/L

Give 40 mEq x 1 (inform Physician) then give 20 mEq Q 2 hours x 3 doses.

Normal serum magnesium concentration is between 1.7 and 2.5 mg/dL (1.2–1.8 mEq/L, 0.6–0.9mmol/L).

Available intravenous (IV) products: Magnesium sulphate 50% (1gm/2ml) contains 2 mmol/L.

Dosing of magnesium supplementation should be written in grams to avoid potential medication errors.

The underlying cause of hypomagnesemia should be identified and corrected.

Standard preparation:

2 gm/100 mL in 5% Dextrose or Normal saline for peripheral line.

4 gm/100 ml in 5% Dextrose or Normal saline for central line.

Infusions SHOULD NOT be faster than 1gm of magnesium Sulfate every 30 minutes.

In the life-threatening setting 4 mL (2 ampules) of a 50% solution of magnesium sulfate diluted in 100 mL of normal saline (16 mEq of Mg; 1 gm MgSO4= 8 MEq Mg) can be administered over 10 min; this is followed by 50 mEq of Mg given over the next 12–24 hour.

All Magnesium infusions must be administered via infusion pumps.

If creatinine clearance (CrCL) <30 mL/min, reduce the dose by 50-75%.

Serum Magnesium

Replace with

1.6 – 1.9 mg/dL, 0.41-0.6 mmol/L

4 gm IV over 2 hrs

1.0 – 1.59 mg/dL, 0.2-0.4 mmol/L

6 gm IV over 3 hrs

< 1.0 mg/dL, < 0.2 mmol/L

8 gm IV over 4 hrs

Available intravenous (IV) products:

Calcium gluconate: 10 ml of 10% Calcium gluconate = 94 mg of elemental calcium.

The underlying cause of hypocalcemia should be identified and corrected.

In critically ill patients with hypoalbuminemia, the calcium level will be altered.

Corrected calcium (mg/dL) = Measured total calcium(mg/dL) + 0.8 (4.0-serum albumin[gm/dL]).

Dosing of calcium supplementation should be written in grams to avoid potential medication errors.

Standard concentration:

Dilute 20 ml of 10% Calcium Gluconate (2 gm) in 100 mL NS.

Final concentration: 1gm/ 50ml NS.

All calcium infusions must be administered via infusion pumps.

Infusions SHOULD NOT be faster than 2 gm of Calcium gluconate over 10 minutes.

Calcium replacement is based upon serum ionized calcium.

Serum Ionized Calcium level

Replace With

Recheck Level

0.875-0.975 mmol/L

4 gm Calcium Gluconate (40 ml of 10%, 4 ampoules).

Next morning.

0.750 – 0.874 mmol/L

6 gm Calcium Gluconate (60 ml of 10%, 6 ampoules).

4 Hours After Replacement.

0.625 – 0.749 mmol/L

8 gm Calcium Gluconate (80 ml of 10%, 8 ampoules).

4 Hours After Replacement.

< 0.625 mmol/L

10 gm Calcium Gluconate (100ml of 10%, 10 ampoules).

4 Hours After Replacement.

Look for possible causes like

● Diarrhea and vomiting.

● Burns.

● Nephrogenic/central diabetes insipidus (which may follow head injury or pituitary surgery).

● Glucosuria in uncontrolled diabetes mellitus (e.g., hyperosmolar hyperglycemia status).

● Medication (e.g., lithium, phenytoin, demeclocycline, corticosteroids, mannitol).

● Excessive administration of saline infusion fluids or drugs with a high sodium content.

Hypernatremia should be treated by administration of free water (preferably via the gut, or otherwise in the form of intravenous D5W).

Don't just arbitrarily give some random amount of water – calculate exactly how much water is required to achieve the desired drop in serum sodium.

Free Water Deficit (FWD) = TBW x (serum [Na] -140) / 140; TBW = wt. (kg) x 0.6 (male) or 0.5 (female).

For patients with chronic hypernatremia (stable elevation >48hr), target reducing the sodium by 10 mEq per day and monitor serum sodium every 4-6 hrly.

For patients with acute hypernatremia, replace the fluid deficit within 24 hours and monitor serum sodium every 2-4 hrly.

For acute symptomatic hyponatremia (Confusion, Headache, Drowsiness, Reduced GCS, Seizures), give bolus of 100 ml 3 percent saline over 10 min (to a total dose of 300 ml).

The goal is to increase serum sodium by 4-6 mEq/l over 4-6 hours.

Remeasure the serum sodium hourly to determine the further plan.

For acute asymptomatic hyponatremia (serum sodium<130mEq/l) give 50 ml bolus of 3 percent saline.

The goal is to prevent the serum sodium from falling further.

Bolus of hypertonic saline may not be necessary if autocorrecting due to water diuresis.

Monitor the patient for symptoms and remeasure the serum sodium concentration 2-4hourly to determine the need for additional therapy.

For chronic symptomatic hyponatremia (Seizures, obtundation, respiratory arrest or with known intracranial pathology like traumatic brain injury, space occupying lesion), give bolus of 100 ml 3 percent saline over 10 min (to a total dose of 300 ml).

In patients with chronic, severe hyponatremia, the maximum rate of correction should be 8 mEq/L in any 24-hour period.

In chronic hyponatremic patients who have mild to moderate symptoms (e.g., headache, fatigue, nausea, vomiting, gait disturbances, confusion) and who have severe hyponatremia (serum sodium <120 mEq/L), initiate intravenous 3 percent saline beginning at a rate of 0.25 mL/kg/hour.

Fluid restriction to below the level of urine output is indicated for the treatment of symptomatic or severe hyponatremia in edematous states (such as heart failure and cirrhosis), syndrome of inappropriate ADH (SIADH), advanced renal impairment, and primary polydipsia.

Depending upon the etiology of hyponatremia, other therapies may include loop diuretics, oral salt tablets, potassium supplementation, or vasopressin receptor antagonists to correct chronic hyponatremia.