Internal medicine
Severe hyperkalemia — the essentials
Severe hyperkalemia is a serum potassium >=6.5 mmol/L and/or any ECG change — a "lab + ECG = act now" emergency. The nursing priority is to read the ECG cue, treat the critical value as cannot-miss, escalate immediately, and administer ordered therapies in the right order: membrane stabilization (IV calcium), intracellular shift (insulin + dextrose, salbutamol), then elimination.
Recognize it (red flags)
- ECG progression, in order of rising danger: peaked T waves → flattened/absent P waves and a long PR → widened QRS → sine wave → VF/asystole
- Symptoms are nonspecific: muscle weakness, fatigue, palpitations, perioral or fingertip paresthesias — trust the value and the ECG, not how the patient looks
- High-risk context: CKD stage 4-5, a missed dialysis session, or an ACE inhibitor, ARB, spironolactone, or potassium supplement
- Widened QRS, sine wave, or loss of P waves = impending arrest — notify the provider STAT and prepare IV calcium
- The ECG can be normal at a dangerously high K+ — a near-normal tracing does not make the value safe
Key numbers
- Normal serum potassium
- 3.5-5.0 mmol/L
- Severity bands (UKKA)
- mild 5.5-5.9 / moderate 6.0-6.4 / severe >=6.5 mmol/L
- Treatment trigger
- K+ >=6.5 mmol/L AND/OR any ECG change
- IV calcium gluconate 10%
- ~10 mL (~1 g) IV over 2-5 min on a monitor; repeat q5-10 min
- Insulin shift
- 10 units (or 5 units) regular insulin IV WITH 25 g dextrose
- Nebulized salbutamol
- 10-20 mg (intentionally 4-8x the bronchodilator dose)
- Recheck potassium
- ~60 min after shift/elimination therapy
Priority nursing actions
- Recognize the critical value and ECG cue, escalate immediately, and put the patient on continuous telemetry with IV access
- Administer therapies PER ORDER in sequence: 1) stabilize with IV calcium, 2) shift with insulin + dextrose and salbutamol, 3) eliminate with a loop diuretic, binder, or dialysis
- Pair insulin shift with dextrose every time (unless already hyperglycemic) and run a structured glucose schedule: baseline, 1 h, 2 h (often 3 h)
- Hold potassium-raising drugs (ACE inhibitor, ARB, MRA, K-sparing diuretic, NSAID, supplements) and dietary potassium per order
- Recheck the potassium ~60 minutes after shift therapy — shift agents are temporary and K+ can rebound
Common NGN / NCLEX traps
- Thinking IV calcium lowers potassium — it stabilizes the myocardium but does NOT lower the value
- Giving insulin without concurrent dextrose — the #1 iatrogenic harm here is hypoglycemia
- Mistaking the high-dose nebulized salbutamol (10-20 mg) for an error — it is intentionally several times the usual dose
- Reaching for sodium polystyrene sulfonate (SPS) as an acute fix — no longer recommended in acute care
- Delaying treatment for a repeat draw when ECG changes are present — act on a true value with ECG changes
For practicing nurses
What’s changed (if you trained a while ago)
- Sodium polystyrene sulfonate (SPS/Kayexalate) is no longer recommended for acute hyperkalemia — questionable efficacy and colonic-necrosis risk; never co-administer with sorbitol.
- A 5-unit insulin regimen (often with more dextrose) is now supported, especially in CKD, low body weight, or low baseline glucose, to cut hypoglycemia (UKKA 2022).
- Structured glucose checks at baseline, 1 h, and 2 h are the standard of care — protocolized order sets cut hypoglycemia from ~24% to ~9%.
- The old "stone heart" warning against IV calcium in digoxin toxicity is now considered largely theoretical/contested — follow the current order and protocol.
On the floor (practical pearls)
- Calcium first, then shift, then eliminate — and remember calcium buys time but does not lower the potassium, so the shift/elimination steps still have to happen.
- Insulin + dextrose is high-alert: independent double-check the dose (5 vs 10 units), the IV route (never subQ for this), and the concurrent dextrose order.
- Hypoglycemia is often delayed because insulin outlasts the dextrose bolus — keep checking glucose, especially if the patient is NPO, non-diabetic, or has CKD; hold/reduce insulin and notify for glucose <70 mg/dL.
- IV calcium is a vesicant: calcium gluconate is preferred peripherally; reserve calcium chloride (~3x the elemental calcium) for a central line or arrest, with close IV-site monitoring.
- Never run calcium and sodium bicarbonate in the same line — calcium carbonate precipitates; flush between or use separate lines.
- Chart the K+ trend, the ECG response (QRS narrowing), the serial glucose, and the time of each drug — escalate for any QRS widening, new bradycardia/AV block, or a malignant rhythm.
Key references
- Emergency Department Hyperkalemia Expert Panel Consensus, Ann Emerg Med, 2024
- KDIGO / UK Kidney Association potassium emergency guidance, KDIGO/UKKA
- Calcium Gluconate — StatPearls, NCBI/NIH, 2024
- Lewis's Medical-Surgical Nursing (Lewis/Harding), Elsevier, 2023
- Davis's Drug Guide for Nurses, F.A. Davis, 2024
Sources: Based on the UK Kidney Association 2022 guideline, KDIGO, the ED Hyperkalemia Expert Panel Consensus, Davis’s Drug Guide, and Lewis/Harding Medical-Surgical Nursing.
