Potassium Imbalance: Hypokalemia vs Hyperkalemia — ECG, Symptoms, Interventions
A potassium of 3.0 and a potassium of 6.5 both trigger lethal dysrhythmias, but the ECG patterns, symptoms, and emergency interventions are mirror opposites. Picking the wrong correction on the NCLEX means choosing the action that kills the patient.
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- Loop / thiazide diuretics
- Vomiting, NG suction
- Alkalosis
- insulin administration
- Renal failure
- K⁺-sparing diuretics (spironolactone)
- Crush injury
- acidosis
- transfusion
- Muscle weakness
- Leg cramps
- Hyporeflexia
- ↓ GI motility, ileus
- Muscle weakness
- Muscle twitching, paresthesias
- Ascending flaccid paralysis
- Intestinal cramping, diarrhea
- Serum K⁺ < 3.5
- flat/inverted T waves
- ★Prominent U waves
- ST depression
- ★Tall peaked T waves (early)
- Serum K⁺ >5.0
- widened QRS, loss of P
- Continuous telemetry
- Check Mg²⁺: low Mg blocks K⁺ repletion
- KCl is a vesicant — check IV site
- Continuous telemetry
- Recheck K⁺ 1 hr post-treatment
- Watch rebound hypokalemia after insulin
- ★IV KCl ≤10 mEq/hr peripheral
- never IV push
- Always use an infusion pump
- ★IV calcium gluconate first
- Insulin + dextrose, bicarb
- K⁺ binders, dialysis
- Eat K⁺-rich foods (bananas, potatoes)
- Restrict K⁺-rich foods
- read labels
- Avoid salt substitutes (contain KCl)
- PVCs, V-tach, V-fib
- Potentiates digoxin toxicity
- Bradycardia, heart block, asystole
- Risk spikes when K⁺ > 6.5
- Cardiac arrest (V-fib)
- paralytic ileus
- Sine-wave QRS pattern
- Cardiac arrest (asystole)
Hypokalemia (< 3.5)
- Loop / thiazide diuretics
- Vomiting, NG suction
- Alkalosis
- insulin administration
Hyperkalemia (> 5.0)
- Renal failure
- K⁺-sparing diuretics (spironolactone)
- Crush injury
- acidosis
- transfusion
Hypokalemia (< 3.5)
- Muscle weakness
- Leg cramps
- Hyporeflexia
- ↓ GI motility, ileus
Hyperkalemia (> 5.0)
- Muscle weakness
- Muscle twitching, paresthesias
- Ascending flaccid paralysis
- Intestinal cramping, diarrhea
Hypokalemia (< 3.5)
- Serum K⁺ < 3.5
- flat/inverted T waves
- ★Prominent U waves
- ST depression
Hyperkalemia (> 5.0)
- ★Tall peaked T waves (early)
- Serum K⁺ >5.0
- widened QRS, loss of P
Hypokalemia (< 3.5)
- Continuous telemetry
- Check Mg²⁺: low Mg blocks K⁺ repletion
- KCl is a vesicant — check IV site
Hyperkalemia (> 5.0)
- Continuous telemetry
- Recheck K⁺ 1 hr post-treatment
- Watch rebound hypokalemia after insulin
Hypokalemia (< 3.5)
- ★IV KCl ≤10 mEq/hr peripheral
- never IV push
- Always use an infusion pump
Hyperkalemia (> 5.0)
- ★IV calcium gluconate first
- Insulin + dextrose, bicarb
- K⁺ binders, dialysis
Hypokalemia (< 3.5)
- Eat K⁺-rich foods (bananas, potatoes)
Hyperkalemia (> 5.0)
- Restrict K⁺-rich foods
- read labels
- Avoid salt substitutes (contain KCl)
Hypokalemia (< 3.5)
- PVCs, V-tach, V-fib
- Potentiates digoxin toxicity
Hyperkalemia (> 5.0)
- Bradycardia, heart block, asystole
- Risk spikes when K⁺ > 6.5
Hypokalemia (< 3.5)
- Cardiac arrest (V-fib)
- paralytic ileus
Hyperkalemia (> 5.0)
- Sine-wave QRS pattern
- Cardiac arrest (asystole)
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Flat T = low K⁺; peaked T = high K⁺ — the T wave mirrors the potassium level.
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