Pathophysiology & Risk Factors

Hypokalemia is a serum potassium below 3.5 mEq/L. Potassium is the primary intracellular cation that sets the resting membrane potential of excitable tissue; when extracellular K+ falls, cells hyperpolarize and need a stronger stimulus to fire, producing weakness, sluggish bowels, and dangerous cardiac instability. Alkalosis shifts K+ into cells and lowers the serum level further (the inverse of acidosis/hyperkalemia).

3 · Severe (<3.0)

2.5 · Respiratory risk (<2.5)

Hypokalemia

Normal

Hyperkalemia

3.5

mEq/L

Signs & Symptoms

EarlyProgresses →

skeletal muscle weakness

legs first, ascending

fatigue

leg cramps

diminished deep tendon reflexes

hypoactive bowel sounds

decreased peristalsis

constipation

Late / Severe

paralytic ileus

cardiac dysrhythmias

PVCs, VT

respiratory muscle weakness

K+ below 2.5 mEq/L

Diagnostics & Labs

Hypokalemia ECG progression

Flattened T wavesearliest change
ST depression
Prominent U waveshallmark
DysrhythmiasPVCs, VT, arrest

Interventions & Priorities

check ECG before treating the number

place on continuous cardiac monitor

verify urine output ≥30 mL/hr

before any K+ replacement

check and replete magnesium

correct first or simultaneously

hold digoxin if hypokalemicHold

notify provider

infuse IV KCl by pump only

never gravity drip, never push

recheck potassium after replacement

Treatments & Medications

IV KCl maximum infusion rate

Peripheral line10 mEq/hr

Central line20 mEq/hr

020 mEq/hr

Patient Teaching

take oral KCl with food

prevents GI ulceration

take oral KCl with a full glass of water

do not crush extended-release tablets

dose dumping risk

eat potassium-rich foods

bananas, oranges; encourage, not restrict

report leg weakness or palpitations

Report Nowescalate immediately

IV potassium push

NEVER push or bolus; causes cardiac arrest

infusion rate exceeding limitperipheral >10 mEq/hr

fatal dysrhythmia risk

burning at IV site

KCl vesicant; slow rate, assess phlebitis/infiltration

ventricular dysrhythmia

PVCs, VT, cardiac arrest

digoxin toxicity

hypokalemia potentiates dig; hold dose

severe hypokalemiaK+ < 2.5 mEq/L

respiratory muscle weakness

Clinical Pearl

Hypokalemia goes flat and slow: flat T waves, flat reflexes, flat bowels, flat energy, and a tell-tale U wave. IV potassium: never push, always pump, always monitor.