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PATIENT'S ELECTROLYTES MANAGEMENT

THE PHARMACIST ROLE PH. AHMED M. ALFIKY

Pharmaceutical Care DepartmentKing Abdullah Medical City

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Solute Homeostasis

• Electrolytes - Charged particles• Cations: Sodium (Na+) 14.61%, 3%, 0.9% 0.45%, 0.225 %,

Potassium (K+) 2 mEq/mL (Potassium Chloride and Phosphate),

Calcium (Ca++) 100 mg/mL , (Calcium Chloride and gluconate ), and

Magnesium (Mg++) 0.8 meq/mL ,4 mEq /mL

• Anions: Bicarbonate (HCO3-),

Chloride (Cl-),

Phosphate (PO4---).

• Non-electrolytes - Uncharged particles• Proteins, urea, glucose, O2, CO2

• Lactated Ringer’s• 130 mEq Na 109 mEq Cl 28 mEq lactate

• 4 mEq K 3 mEq Ca

• 0.9% NaCl 154 mEq Na 154 mEq Cl

• 0.45% NaCl 77 mEq Na 77 mEq Cl

Why is it important to replace

the electrolytes ?

Potassium• Regulates resting membrane potential.• Regulates fluid, ion balance inside cell.

- Hypokalemia:• Neuromuscular disorders

– Weakness, flaccid paralysis, respiratory arrest, constipation• Hypotension.• Dysrhythmias• Cardiac arrest.

- Hyperkalemia :• Early – hyperactive muscles , paresthesia

• Late - muscle weakness, flaccid paralysis

• Peaked T-waves

• Dysrhythmias– Bradycardia, heart block, cardiac arrest

HyponatremiaSymptoms

• Anorexia • Headache • Nausea • Emesis• Impaired response to verbal stimuli • Impaired response to painful stimuli • Bizarre behavior • Hallucinations • Obtundation • Incontinence • Respiratory insufficiency• Decorticate or decerebrate

posturing • Bradycardia • Hypertension or hypotension • Altered temperature regulation

• Dilated pupils • Seizure activity • Respiratory arrest • Coma• Hypotension• Renal failure as consequence of

hypotension• Tachycardia• Weakness

• Muscular crampsThirst

• Lethargy

• Irritability

• Seizures

• Fever

• Oliguria

HYPOMAGNESEMIA• Irritability, confusion, arrhythmias, weakness,

nystagmus,seizures, coma, and death• concomitant hypokalemia and hypocalcemia

Hypocalcemia• Tetany, muscle spasms, lethargy, seizures

Chloride• Tonicity Disturbence

• Working with physicians, pharmacists play an important role in the determination of underlying causes of these disorders, particularly when disorders are medication-related, and in providing knowledge of the potential implications of individual medications.

• Pharmacists also often evaluate and recommend treatment of electrolyte disturbances.

• What are the standards for safe and effective administration in Peripheral Vs Central line ?

the Recommended maximum concentrations and maximum rates of infusion?

• Available Intravenous and oral forms?

• How to replace and maintain the electrolytes?

- REPLACEMENT DOSE, central venous catheter.

- MAINTANCE DOSE.

• Physician orders verification and calculations

millmoles (mmol) , milliequivalnts (mEq) or grams or percentage.

• Proper Labeling .

• High risk Electrolytes? auxiliary labeling

Concentrated electrolytes shall not be part of routine floor stock.

• Administration :

- Do not give IV PUSH (except for magnesium and calcium).

- Mechanical infusion pump for all replacement electrolytes.

• Renal function • Salt form• acid/base status • Time of lab draw• Route of administration• Absorption issues• Diarrhea, nausea/vomiting

Potassium

HypokalemiaSeverity Serum K concentration

(mEq/L)Initial I.V. K

replacement dose

Mild/Moderate2.5-3.4 20-40 mEq

Severe <2.5 40-80 mEq

• Every 1 mEq/L below 3.5 represents a 100-200 mEq deficit.

• One time dose of 40 mEq is not adequate replacement.

• Magnesium levels should be monitored and replacement given if necessary since potassium repletion is ineffective in the presence of hypomagnesemia.

• Oral replacement if asymptomatic and K is < 3.8 mEq/L.

• Oral = IV K at same doses. Potassium chloride slow release tablet contains 8 mmol potassium per tablet. (Tablets should not be crushed or chewed).

• Liquid has unpleasant taste.

.• Adult doses from 40-100 mEq/day may be required for potassium repletion given in 2 - 4

divided doses per day.

• In adults, start with 20-40 mEq/day and titrate to desired level. A 40 mEq dose may be

given every 2 hours for a maximum dose of 120 mEq within a 6 hour period.

• Oral potassium can be prescribed in conjunction with IV potassium.

• When oral potassium therapy is combined with parenteral supplementation for adults, a maximum total dose (IV + PO) is 120 mEq within a 6 hour period.

• Do not use sustained release potassium products, when an immediate response is desired. potassium chloride solution, should be used for a quicker response.

• Avoid dextrose vehicles - may stimulate insulin release and decrease K specially in Initial replacement therapy.

• Potassium salts MUST NEVER be given IM or as an IV push.

• Potassium levels must be checked after each replacement dose. If using immediate release preparations, a level should be checked no sooner than 60 minutes.

If using a sustained release product, a level should be checked no sooner than 3 hours.

Patients receiving maintenance doses of oral potassium do not require levels after each dose.

• All IV maintenance infusions with KCl at a concentration greater than 40 mEq/L must be administered via an infusion pump.

• Peripheral administration.

• Central administration.

• Cardiac Monitoring:

greater than 10 mmol/hour

SERUM less than or equal to 2.5 mmol/L.

DOSE exceeds 80 mmols

- Rapid infusion of KCl may cause cardiac arrest.

- Risk Factors for developing hypokalemia:

• Severe vomiting/diarrhea• amphotericin B• Chronic diuretics• metabolic alkalosis• insulin• beta2 agonists (e.g., terbutaline)• Decreased intake of K+

• Acid/base imbalance• Trauma and stress• Increased aldosterone

• Beware if diabetic– Insulin pushes K+ into cells– Ketoacidosis – H+ replaces K+, which is lost in urine

• β – adrenergic drugs or epinephrine

• A single salbutamol nebulizer treatment may lower serum K by 0.2-0.4 mmol/L.

• A single dose of succinylcholine will increase serum K by 0.5-1.0 mmol/L.

• Hyperkalaemia may occur with TMP/SMX (trimethoprim-sulfamethoxazole) therapy and with the use of hypertonic agents (e.g. D50, mannitol).

• A serum K of 3-4 mmol/L correlates with a 100-200 mmol K deficit. At a serum K of 2-3 mmol/L, the deficit is 200-400 mmol.

• Serum potassium may be expected to increase by ˜ 0.25 mmol/L for each 20 mmol IV KCL infused.

• Hypokalemia :• intracellular shift, including albuterol, insulin, theophylline, and

caffeine.

Hyperkalaemia:- Risk Factors for developing hyperkalemia:

• Serum K+ > 5.5 mEq / L

• Check for renal disease

• Massive cellular trauma

• Insulin deficiency

• Addison’s disease

• Potassium sparing diuretics (spironolactone, amiloride, etc.)

• Decreased blood pH

• Exercise pushes K+ out of cells• use of high dose TMP/SMX for PCP in HIV infected patients

- Hemodialysis

Management :

• 10% Calcium Gluconate or Calcium Chlorideas calcium will antagonize the effects of potassium to rapidly stabilize cardiac muscle function

• Insulin (0.1U/kg/hr) and IV Glucose• albuterol • Metabolic alkalosis (if the patient is acidemic)

– 1 L H20 with 150meq of NaHCO3• Lasix 1mg/kg (if renal function is normal)

• Sodium polystyrene sulfonate acts as a cation exchange resin, binding to potassium in the gastrointestinal tract to facilitate elimination.

• Renal replacement therapy

Magnesium

HYPOMAGNESEMIA

• thiazide and loop diuretics, amphotericin, cisplatin, cyclosporine, and digoxin.

• 1 g IV Mg = 8 mEq= 4 mmol

• Normal serum levels needed for potassium and calcium replacement (If the magnesium concentration is low, it should be corrected, otherwise it will be difficult to normalize potassium and calcium).

• Approximately 50% of the dose given is renally eliminated.

• Replace P.O. if patient can tolerate (diarrhea -rate limiting side effect ,may be reduced by dividing daily doses).

Serum Mgconcentration (mEq/L)

Oral Intravenous

1.0-1.5 (mild/moderate) Magnesium oxide400 mg 1-2 tablets TID

8-32 mEq

<1.0 (severe) N/A 32-64 mEq

• An additional consideration is that magnesium levels drawn after infusion may be falsely elevated due to magnesium’s slow distribution into body tissues

• Takes 3 to 5 days for total repletion.• Max IV rate = 1 g per hour.• < 20% (200 mg/ml) concentration before administration.

• MAX. CONC. : 1 gm in 5 ml D5W or NS• MAX. INFUSION RATE: 1 gm over 7 minutes

• For Mg levels > 1.2 mg/dl AND asymptomatic, oral* therapy may be used:

• *Oral absorption is variable with 15-50 % of a dose being absorbed.

1-2 tablets daily

• Magnesium sulfate may be given IM, however it can be very painful. Doses greater than 1 gm must be given in different injection sites.

• For symptomatic patients, bolus doses of IV magnesium are required.

• For asymptomatic patients, adding magnesium to the patient's maintenance IV fluids will allow for better retention of magnesium

• HYPERMAGNESEMIA

• ntravenous calcium (chloride or gluconate) to stabilize cardiac and neuromuscular function.

• loop diuretics or renal replacement therapy

PHOSPHOROUS

HYPOPHOSPHATEMIA

• Role in several important body functions • Potassium Phosphate.• Sodium Phosphate.• Sodium Phosphate and Normal Saline.• Recommended Total dose infused over 4-6 hrs to reduce risk of (hypocalcemia

and soft tissue calcification, hypotension, renal failure)• Oral Phosphateshould be used if asymptomatic/mild hypophosphatemia (can

cause diarrhea) (will decrease Mg absorption)• Magnesium, calcium and aluminum containing antacids may bind phosphorus

and prevent its absorption.

PO4 Concentration (mg/dL) IV replacement dose

2.3-3.7 0.08-0.16 mmol/kg

1.5-2.2 0.16-0.32 mmol/kg

<1.5 0.32-0.64 mmol/kg

• Millimoles• Maximum rate= 10 mmol/hr

- KPhos 15 mmol / 100 ml NS or D5W over 3 hours centrally.*

- NaPhos 15 mmol / 100 ml NS or D5W over 3 hours centrally.

Unless total calcium is < 7.5 mg/dL or > 11 mg/dL (corrected) phosphorus is > 2 mg/dL OR significant renal dysfunction

(Clcr < 10 ml/min)• IDEAL body weight (IBW) or adjusted weighs for obese patient.• 4 hours after replacement completed. • Renal insufficiency (CLcr <20ml/min): reduce dose by 50%• Maximum is 15 mM of sodium phosphate in 100 ml dextrose 5%

in water• As a guideline, the phosphorus level will increase by an average

of 1.2 mg/dl with a dose of 0.25mmol/kg

• Hyperphosphatemia

• phosphate binders such as calcium carbonate, calcium acetate, and sevelamer orally with meals to reduce phosphorus absorption from the gastrointestinal tract.

• renal replacement therapy

CALCIUM

HYPOCALCEMIA

• NORMAL LEVELS: Total Calcium: 8.4-10.2 mg/dl (2.1-2.6 mmol/L) • Highly protein bound so always calculate corrected calcium.

Corrected calcium = [(4-albumin) x 0.8] + serum calcium.• Ionized calcium remains normal in low albumin states. • Calcium chloride and Calcium gluconate • Calcium chloride only used in severe situations typically codes• Gram , mmol

Total Ca (mg/dL) Dosing Continuous IV dose

Mild/moderateAnd asymptomatic

0.08-0.16 mmol/kg 4.56-9.12 mEq Ca over 30-60 minutes

<7.5 (Severe)Or symptomatic

3 g calcium gluconate over 10 minutes

repeat PRN

13.6 mEq Ca over 10 min. repeat PRN

– If the magnesium concentration is low, it should be corrected, otherwise it will be difficult to normalize potassium and calcium

– MAXIMUM RECOMMENDED CONCENTRATIONS:

• Calcium gluconate: 1 gm in 50 ml D5W or NS.

• Calcium chloride*: 1 gm in 100 ml D5W or NS

– INFUSION RATE: Infuse over 30-60 minutes.

Rapid administration may cause bradycardia, hypotension and vasodilation.

– Administration via a central or deep vein is preferred. IM or SC?

– Phosphate and Calcium replacements, Determine Ca x PO4 product in mg/dl before administering calcium.

If product is greater than 60 mg/dl, there is an increased risk of calcium phosphate precipitation in the cornea, lung, kidney, cardiac conduction system, and blood vessels.

• Usual maximum total daily dose is 15 g calcium gluconate.

• As a guideline, the total calcium will increase by 0.5 mg/dl for

every gram of calcium gluconate given intravenously.

• ORAL CALCIUM Absorption is variable and depends on PTH, Vitamin D, and gastric pH.

• USUAL DOSE: 500- 2000 mg elemental calcium a day, in divided doses (BID-QID)– ADVERSE EFFECT: Constipation

• For each 5 units of packed RBCs transfused, administer 1-2 grams (1-2 amps) of calcium gluconate.

Sodium

• May reflect increased, decreased or normal total body sodium• Sodium is the major cation that determines serum osmolality, • Must assess osmolality to treat Various causes (SIADH, CHF, Ascites)• Normal serum sodium levels are 136 -145 mEq / L.• Max rate of increase in serum sodium is 8-12 mEq/L in 24 hrs• Assess underlying cause and treat first.• acute onset hyponatremia is more likely to be symptomatic and • can be more rapidly corrected compared to chronic hyponatremia, which is

usually not associated with as severe of symptoms and should be corrected slowly.

** All replacement doses reflect dosing for patients with Normal renal function**

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Treatment of Hyponatremia

• Correct serum Na by 1mEq/L/hr• Check serum Na q4hr• Use 3% saline in severe hyponatremia• Central venous catheter, venous irritation and pain at the

injection site.• Administer osmotic diuretic (Mannitol) to excrete the water

rather than the sodium• Goal is serum Na 130• Avoid too rapid correction

• Hypernatremia: Plasma Na+ > 145 mEq / L

– Excess Na intake (hypertonic IV solution)– Excess Na retention (oversecretion of aldosterone)– Loss of pure water

• Long term sweating with chronic fever• Respiratory infection → water vapor loss• Diabetes (mellitus or insipidus) – polyuria

– Insufficient intake of water (hypodipsia)

Management:• 45% NSS. If caused by both Na and fluid loss, will administer

NaCL. If inadequate renal excretion of sodium, will administer diuretics.