waves and wide QRS complex. What is the next best step?
a. Dialysis
b. IV calcium chloride
c. IV insulin w/ dextrose
d. Calcium resonium
e. Nebulized salbutamol
answer: B
ECG changes indicate serum K+ above 7 mEq/L, priority is to protect the heart
ECG changes in hyperkalemia
- The T wave becomes taller and more peaked (K+ ~ 7-8 mEq/L); it almost looks like the Eiffel Tower (tall, peaked, with narrow base)
- P wave amplitude decreases, the PR interval lengthens, and the QRS widens (K+ >8 mEq/L).
- P waves disappear (sinoventricular rhythm) and the QRS becomes sinusoid (K+ >10 mEq/L). V Fib usually follows.
Treatment of
Hyperkalemia
•
acute therapy is warranted if ECG changes are present, or if patient is
symptomatic
•
tailor therapy to severity of increase in [K+] and
ECG changes
[K+] <6.5 and normal ECG
treat
underlying cause, stop K+ intake, (increase the loss of K+ ) via urine and/or GI tract
[K+] between 6.5 and 7.0, no ECG
changes:
(shift k+ into cells) add
insulin to above regimen
[K+] >7.0 and/or ECG changes:
first
priority is to(protect the heart), add calcium gluconate to above
1.
Protect the Heart
• calcium
gluconate 1-2 amps (10 mL of 10% solution) IV
•
antagonizes cardiac toxicity of hyperkalemia, protects cardiac conduction
system, no effect on serum [K+]
•
onset within minutes, lasts 30-60 min (may require repeat doses during
treatment course of hyperkalemia)
2. Shift
K+ into Cells
• regular
insulin (Insulin R) 10-20 units IV, with 1-2 amp D50W (give D50W before
insulin)
onset of action 15-30 min, lasts 1-2 h
monitor capillary blood glucose q1h
because of risk of hypoglycemia
can repeat every 4-6 h
caution giving D50W before insulin if
hyperkalemia is severe as it can cause a serious arrhythmia
•
NaHCO3 1-3 ampules (given as 3 ampules of 7.5%
or 8.4% NaHCO3 in 1L D5W) onset
of action 15-30 min, transient effect, drives K+ into
cells in exchange for H+, more
effective if patient has metabolic acidosis
• B2-agonist
in nebulized form (dose = 2 cc or 10 mg inhaled) or 0.5 mg IV
onset of action 30-90 min, stimulates
Na+/K+
ATPase
caution if patient has heart disease as
may result in tachycardia
3.
Enhance K+
Removal from Body
• via
urine (preferred approach)
furosemide
(≥40 mg IV), may need IV NS to avoid hypovolemia
• via
gastrointestinal tract
cation-exchange
resins:
calcium resonium or sodium polystyrene sulfonate : increasingly falling out of
favor due to risk of colonic necrosis; works by binding Na+ in exchange for K+, and controversial how much K+ is actually removed
lactulose
PO to avoid constipation (must ensure that patient has a bowel movement after resin
is administered – main benefit may be the diarrhea caused by lactulose)
kayexalate
enemas with water
• dialysis
(renal failure, life threatening hyperkalemia unresponsive to therapy)
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