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Causes of Hyperkalemia
(nl. K+ levels btw 3.5-5.0 mEq/L)
- Acute kidney failure
- Chronic kidney failure
- Obstructive uropathy
- Rejection of a kidney transplant
- Addison's Dx (d/t lack of aldosterone)
Other Causes of Hyperkalemia
(mostly concurrent with kidney dx)
- -Acidosis - moves K+ from inside of cell to outside in the bloodstream.
- -Tissue Injury - burns, hemolytic conditions, GI bleeding, Rhabdo, Surgery, Trauma, Tumors.
- -Salt Substitutes
- -High K+ intake
Other Causes cont:
- Insulin deficiency, hyperglycemia, and hyperosmolality
- Increased Tissue Catabolism
- Digitalis Overdose (inhb. ATP pump)
Other causes cont:
- * Drugs - K+ Sparing Diuretics
- - spironolactone
- - amiloride
- - triamterene
- * ACEI's
- * BB
Sx. of Hyperkalemia
- Usually none - unless serious
- Irregular heartbeat (arrythmias)
- Weak or absent pulse
- Nausea/ Diarrhea
- Muscle Weakness/Paralysis
Signs and Tests
ECG may show potentially dangerous arrhythmias:
- *Heart block that may become a complete heart block
- *Slower than normal heartbeat (bradycardia) that progressively slows
- *Ventricular fibrillation
- *Pulse may be slow or irregular
- Dialysis -- to reduce total body potassium levels, esp if kidney function is compromised
- Intravenous calcium -- to temporarily treat muscle and heart effects of hyperkalemia
- Intravenous glucose and insulin -- to reverse severe symptoms
- Sodium bicarbonate -- to reverse hyperkalemia caused by acidosis
Long Term Tx.
- Cation-exchange resin medications, such as sodium polystyrene sulfonate (Kayexalate) -- K+ binder
- Depends on dx state
- loop diuretics with CKD
- Cardiac arrest
- Changes in nerve and muscle (neuromuscular) control
Algorithm for Tx.
- Is life-threatening hyperkalemia present? (ECG changes? Serum K > 6.5 mEq/L? High-risk as renal failure, receiving dialysis, causative medications?)
A. If No (Life-threatening hyperkalemia is not present) --> Resin exchange with laxative, loop diuretic as furosemide, dialysis
- *Kayexalate (Na Polystyrene Sulfonate) 30 gm in 100 cc 20% sorbitol PO q3-4h. Kayexalate 50 gm in 200 cc 20% sorbitol retention enema 30- 60 min q 4- 6h (decreased 0.5-1 meqK)
- *Furosemide (Lasix) 40-80-160 mg IV
- B. If Yes (life-threatening hyperkalemia is present)-->
- -Step 1: Stabilize the myocardium: (IV Calcium infusion)
- *IV Calcium Chloride (27.2 mg/dL calcium) or Calcium gluconate (8.8 mg/dL calcium) 10 mL (1 amp) of 10% solution (500-1000 mg) IV infusion over 2-3 minutes.* Be extra careful when using calcium infusion in patients with concurrent digitalis toxicity, it could worsen brady-arrhythmia and potentially cause cardiac arrest; use EKG monitor. - for slow infusion, may give the calcium solution in 250 mL D5W and given over 30 minutes.
- -Step 2: Shift potassium into cells: (IV glucose +/- insulin +/- Na bicarbonate; Albuterol nebulizer Rx or IV infusion)
IV 25 - 50 gm of glucose (25-50 g = 1-2 ampules of 50% dextrose D50W or 250-500 mL of D10W solution) +/- IV Regular insulin 10 units - May add Na HCO3 7.5% 50 cc amp 1 -2 amp in the setting of substandial metabolic acidosis (bicarbonate <22 mEq/L)
- -Albuterol nebulizer Rx can be administered at a dosage of 10 to 20 mg in 4 ml of saline by nasal inhalation over 10 minutes or by a 0.5 mg I.V. infusion.
- - Beta-agonists decrease plasma potassium levels. Albuterol can be given via a nebulizer (10-20 mg in 4 mL of saline) or via IV infusion (0.5mg). The dosages of B-agonists administered in this setting are relatively high, ranging from 4 to 8 times that recommended for Rx of an acute asthma exacerbation).
- The major adverse effects are tremor, tachycardia, anxiety, and flushing.
- -Step 3: Enhance elimination of potassium: (Kayexalte, Lasix, Dialysis)
- Resin exchange with laxative: Kayexalate (Na Polystyrene Sulfonate) 30 gm in 100 cc 20% sorbitol PO q3-4h. Kayexalate 50 gm in 200 cc 20% sorbitol retention enema 30- 60 min q 4- 6h (decreased 0.5-1 meqK)
- Loop diuretic as furosemide (Lasix) 40-80-160 mg IV
- Hemodialysis - It is the Rx of choice for life-threatening hyperkalemia that is refractory to medical management. It may decrease the serum K level by 1.0 - 1.5 mEq/L for each hour of dialysis.