hyperkalemia
TRANSCRIPT
Hyperkalemia
Elevation of potassium level in the blood.
Immediate QuestionsA. Is the lab result correct? Consider pseudohyperkalemia, especially if the ECG shows no changes of hyperkalemia. There are a number of causes of factitious hyperkalemia, the most common being the tourniquet method of drawing blood. A tight tourniquet around an extremity can elevate the potassium. Hemolysis of a blood sample prior to the chemical determination is another source of error. Extreme leukocytosis (>70,000) or thrombocytosis (>1,000,000) can elevate the serum potassium. If there is a question, obtain a plasma potassium.
Immediate Questions
B. What are the vital signs?
C. What is the patient's urine output?
Immediate QuestionsD. What does the ECG show? The ECG is the most important test, (besides the potassium level). It provides more of a "bioassay" than the serum potassium. Changes seen with potassium increase include peaked T waves, flat P waves, prolonged PR interval and a widened QRS complex, progressing to a sine wave and arrest.
Immediate QuestionsE. Is the patient taking any medication that could raise the potassium level? Is the patient receiving potassium in an intravenous solution? If the patient is receiving spironolactone, triamterene, indomethacin and other NSAIDs; ACE-inhibitors, trimethoprim / sulfamethoxazole, pentamidine, succinylcholine; stop these medications immediately.
Differential DiagnosisA. Redistribution 1. Acidosis drives potassium out of the cells and can cause hyperkalemia 2. Cellular breakdown a. Rhabdomyolysis b. Hemolysis c. Tumor lysis syndrome
Differential DiagnosisB. Increased total body potassium 1. Inadequate excretion
a. Renal caused (acute or chronic
renal failure)
b. Mineralocorticoid deficiency or
Addison's disease
c. Drug-induced (potassium sparing
diuretics [e.g., spironolactone]
and ACE-inhibitors)
2. Excessive intake
Differential DiagnosisC. Pseudohyperkalemia 1. Hemolysis of the specimen 2. Prolonged period of tourniquets occlusion prior to blood draw 3. Thrombocytosis/leukocytosis
Plan
The severity of hyperkalemia (as judged by the serum level and the ECG) dictates treatment.
A. Repeat any abnormal value, taking care to avoid hemolysis, while assessing for increased WBC or platelets.
B. Prevention of further hyperkalemia; discontinue any potassium administration and any contributing drugs.
PlanC. Calcium administration. Calcium counteracts membrane effects andprotects the heart. Calcium antagonizes the membrane effects of hyperkalemia and restores normal excitability within minutes. Administer one to two ampules of calcium gluconate, (10-20 mL of a 10% solution IV over 3-5 minutes), with the patient on a cardiac monitor.
PlanD. Potassium can be quickly shifted into cells by the administration of alkali or glucose plus insulin (one ampule D50 and 10 units regular insulin).Sodium bicarbonate (1 ampoule [44 mmol] of bicarbonate) may be administered intravenously over several minutes.
PlanE. Remove potassium from body. Kayexolate may be administered orally or as an enema. Remember that this will trade potassium for sodium and result in a sodium load. Normal saline diuresis can assist removal of potassium.
ACUTE THERAPY OF HYPERKALEMIA
Condition: ECG changes of hyperkalemia
Therapy: Calcium gluconate (10%) 10 ml IV over 3 minutes. Repeat in 5 minutes if needed. Follow with 10 units regualar insulin IV; the insulin may be by IV push, but must be followed with 1 ampule D50 IV push; alternatively, 10 unity regular insulin in 500cc D20 may be infused over 30 to 60 minutes.
Comment: Lasts only 30 to 60 minutes. No bicarbonate after calcium.
ACUTE THERAPY OF HYPERKALEMIA
Condition: After acute phase or if no ECG changes
Therapy: Kayexalate: Oral dose of 30 to 60 grams in 50 ml sorbitol (20%). Rectal dose of 50 grams in 200 ml sorbitol(20%) as retention (30 to 45 minutes) enema.
Comment: Oral dose preferred (enemas are only if patient cannot take po).
ACUTE THERAPY OF HYPERKALEMIA
Condition: If renal failure
Therapy: Hemnodialysis as soon as possible. Kayexalate also will be effective, but not immediately.