Peaked T waves, long PR, lost P, widening QRS, arrest
Fluid, Electrolyte & Acid-Base · Topic 15 of 23
Hyperkalemia
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Hyperkalemia simulator
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Hyperkalemia
Na⁺SodiumWNL
K⁺PotassiumPriority
Cl⁻ChlorideWNL
Ca²⁺CalciumWNL
Mg²⁺MagnesiumWNL
PO₄³⁻PhosphateWNL
ECFVolume (ECF)WNL
pHpHWNL
Bedside monitor · pattern
Hyperkalemia
High extracellular potassium partially depolarizes cells, progressively poisoning myocardial conduction.
Direct physiologyPartial depolarization→Peaked T waves→QRS widens→Sine wave
ECG responsePeaked T waves
Tall, narrow, symmetric, tented T waves are the FIRST ECG change of hyperkalemia. Seeing them means the level has already reached the heart.
Neuronal excitabilityNormal
SuppressedBalancedHyper
GutGut motility is running faster than it should.
PerfusionEuvolemic
100%
Extracellular volume at baseline. The dashed line marks euvolemia.
What the nurse would notice
Hyperkalemia across body systems
Weakness, paresthesias; flaccid paralysis when severe
Nausea, diarrhea, hyperactive bowel sounds, cramping
Oliguria or kidney failure is usually the cause
Teaching model, not a clinical calculator. Patterns show high-yield directional relationships under the stated assumption. Real symptoms, ranges and treatment depend on cause, acuity, comorbidities and local protocols.
Signs & symptoms
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Fluids & Electrolytes · K⁺
Hyperkalemia
Too much potassium in the blood. The danger is the heart: dysrhythmias up to VF or asystole.
4.2K⁺ mEq/LNormal
Lead II · example patient · drag the K⁺
3.55.06.08.5
Illustration. ECG changes follow K⁺ only loosely — peaked T waves show in only about a third of patients, some jump straight to a deadly rhythm, and a normal ECG doesn't rule it out.
01 · The numberK⁺ 6.0 or higher: treat now, call the provider
02 · The dangerPeaked T waves: the earliest ECG sign
03 · The fixIV calcium first — protects, doesn't lower K⁺
01
What causes it
#1 cause: kidney failure
Kidneys can't get rid of it
Kidney failurethe kidneys remove most K⁺Missed or shortened dialysisAdrenal insufficiency (Addison's)low aldosterone: K⁺ kept, Na⁺ lost
Drugs & intake that add or hold K⁺
ACE inhibitorsARBsSpironolactoneK⁺-sparing diureticNSAIDsTrimethoprimHeparinK⁺ supplementsSalt substitutespotassium chloride
Cells spill K⁺ out
Metabolic acidosisH⁺ moves in, K⁺ moves outBurnsCrush injuryOther tissue breakdown
02
What you'll see
Muscle weakness that starts in the legs and moves up first signs
Paresthesias (tingling) and muscle cramps
Abdominal cramping, diarrhea, hyperactive bowel sounds
Hyporeflexia → absent reflexes · flaccid paralysis severe
Breathing muscles weaken: dyspnea, tachypnea report now
Bradycardia → VF or asystole code risk
Can be silent — report a critical K⁺ right away, even if the patient feels fine.
03
Labs & diagnostics
Serum K⁺ above 5.0 mEq/L (normal 3.5–5.0; labs vary slightly)
12-lead ECG at K⁺ 6.0 or higher + continuous monitoring
ECG order: peaked T → long PR → lost P → wide QRS → sine wave
Hemolyzed sample, no symptoms, normal ECG? Redraw before treating
04
Red flags
Any ECG change: peaked T, wide QRS, lost P waves, bradycardia report now
K⁺ 6.0 or higher, even if the patient feels fine call now
Ascending weakness with trouble breathing report now
ECG changes persist after calcium: repeat dose as ordered
Low blood glucose after insulin — can come hours later
K⁺ climbing again at 4–6 h — the shift wore off
05
Treatment: protect, shift, remove
In order: protect the heart → shift K⁺ into cells → remove K⁺
Do right now
1
→Cardiac monitor oncontinuous · 12-lead ECG
2
→IV calcium gluconateif the ECG has changed
3
→Insulin + dextrose IVas ordered · albuterol neb as an add-on
4
Recheck K⁺ at 1–2 h and 4–6 hglucose often for about 6 h
ProtectCalcium · steadies the heart
Calcium gluconate IV
Works within about 3 minutes · lasts only 30–60 minutes.
Doesn't lower K⁺ShiftInto cells · temporary
Regular insulin + dextrose Albuterol neb
Insulin 10 units IV with 25 g dextrose — K⁺ falls within 15 min, peaks at 30–60 min. Sodium bicarbonate only for acidosis.
K⁺ rebounds as it wears offRemoveOut of the body
K⁺ binders Loop diuretic Dialysis
Binder by mouth or enema · loop diuretic if the kidneys work · hemodialysis if severe or not responding.
Loop diuretic only if the kidneys workSerum potassium 6.8 with peaked T waves. Calcium gluconate rings the heart cell and the T waves settle while potassium stays 6.8. Insulin then shifts potassium into the cell (5.6), and diuretics, binders or dialysis remove the rest (4.6).
Doses & what to watch
Calcium gluconate 10%, 30 mL IV over 10 minrepeat if ECG changes persist · calcium chloride 10%, 10 mL, is preferred in cardiac arrest
Regular insulin 10 units IV + 25 g dextrosethe insulin outlasts the dextrose → hypoglycemia can appear hours later · check glucose often for about 6 h
Albuterol 10–20 mg by nebulizeran add-on to insulin, not a replacement
K⁺ binders: sodium polystyrene sulfonate, patiromer, sodium zirconium cyclosilicateby mouth or enema · UK guidance has dropped polystyrene resins acutely in favor of the newer two
UK guidance: 5 stepsprotect the heart, shift, remove, monitor, prevent — removal starts early, not strictly last
UK severity bandsmild 5.5–5.9 · moderate 6.0–6.4 · severe 6.5 or higher (mmol/L = mEq/L for K⁺)
Low or no urine outputpoints to kidney failure — and the K⁺ is at risk of rising further
06
After insulin: watch the glucose
A chart of the 6 hours after IV insulin and dextrose are given together. The dextrose curve rises at once and holds the blood glucose up, then wears off within about the first hour. The insulin curve lasts much longer. Once the dextrose is gone, the blood glucose line dips toward 70 mg/dL while the insulin is still working: check the blood glucose often for about 6 hours and watch for lows.
07
Nursing priorities
Continuous cardiac monitor before anything else
Call the provider — critical K⁺, even if the patient feels fine
IV calcium if the ECG has changed, then insulin + dextrose, as ordered
Hold K⁺ supplements and K⁺-raising meds, as ordered
Recheck K⁺ at 1–2 h and again at 4–6 h
Check blood glucose often for about 6 h after insulin
Strict I&O; watch muscle strength and breathing
08
Hypo or hyper?
| Hypo K⁺ | Hyper K⁺ | |
|---|---|---|
| Level | K⁺ below 3.5 mEq/L | K⁺ above 5.0 mEq/L |
| ECG | Flat T · ST depression · U wave | Peaked T · lost P · wide QRS · sine wave |
| Muscles | Weak (legs first), cramps, low reflexes | Weak (legs first) → flaccid paralysis |
| Gut | Hypoactive bowel sounds, constipation → ileus | Cramping, diarrhea, hyperactive bowel sounds |
| Causes | Loop / thiazide diuretics · vomiting · NG suction | Kidney failure · ACE-I / ARB · spironolactone |
| Fix | Replace K⁺ — never by IV push | Give IV calcium first, then shift and remove K⁺ |
09
Teach your patient
Avoid salt substitutes — they are potassium chloride
Limit high-potassium foods: bananas, oranges, potatoes, tomatoes
On dialysis: go to every full session
Ask before OTC NSAIDs or potassium supplements
Report muscle weakness or tingling
Calcium protects the heart but never lowers K⁺. Insulin shifts K⁺ into cells — temporarily. Binders, a loop diuretic or dialysis remove it.
Sources · Management of hyperkalaemia in adults (UK Kidney Association, July 2026) · Medical-Surgical Nursing 10.3 Electrolyte Imbalance (OpenStax) · Hyperkalemia (Merck Manual Professional) · High potassium level (MedlinePlus) · Healthy eating for adults with CKD (NIDDK) · Acute ascending muscle weakness from hyperkalemia (Kimmons et al., 2014) · Fundamentals of Nursing 20.1 (OpenStax) · Consequences of hyperkalemia (Campese & Adenuga, 2016) · Films: the NurseSavvy learning-flow visuals · Follow your facility's protocol for hyperkalemia.
Hyperkalemia
A potassium of 6.8 mEq/L with peaked T waves means the heart could stop in minutes. The treatment sequence you choose — and the order you choose it in — determines whether it does.
Emergent hyperkalemia management follows three priorities in a specific order: stabilize the heart, shift potassium intracellularly, then remove potassium from the body. First, IV calcium gluconate (or calcium chloride via central line) is given to stabilize the cardiac membrane — it does NOT lower potassium but buys time by raising the threshold for cardiac depolarization. Effect is immediate (1-3 minutes) and lasts 30-60 minutes. Second, potassium is shifted into cells using regular insulin (typically 10 units IV) co-administered with dextrose (D50) to prevent hypoglycemia, and/or nebulized albuterol. Insulin-dextrose onset is 15-30 minutes, lasting 2-6 hours. Sodium bicarbonate may be used if acidosis is present since correcting pH drives potassium intracellularly. Third, potassium is eliminated via sodium polystyrene sulfonate orally or rectally, loop diuretics if renal function allows, or emergent hemodialysis for refractory cases. Nursing priorities include continuous cardiac monitoring, checking blood glucose every 1-2 hours after insulin administration, and monitoring for rebound hyperkalemia as shifting agents wear off.
Key Distinctions
Calcium gluconate protects the heart but does NOT lower potassium — students frequently select it as a potassium-lowering intervention. Insulin shifts potassium into cells (temporary fix) while a potassium binder removes it from the body (actual elimination) — these are different mechanisms with different timelines. Regular insulin is used, never rapid-acting analogs like lispro, for this IV protocol.
Clinical Pearl
Think C-S-E: Cardiac stabilization first (calcium), Shift second (insulin + glucose), Eliminate last (a potassium binder, dialysis). Calcium buys time, insulin buys hours, elimination solves the problem.
Recognition
Normal serum potassium is 3.5-5.0 mEq/L. Hyperkalemia (>5.0 mEq/L) most commonly results from renal failure (decreased excretion), potassium-sparing diuretics, ACE inhibitors/ARBs, massive tissue destruction (burns, crush injuries), and metabolic acidosis (hydrogen ions shift into cells, potassium shifts out).
The cardiac effects follow a predictable ECG progression: first peaked T waves, then widened QRS complex, then flattened P waves, and finally a sine wave pattern preceding cardiac arrest. The earliest ECG change — peaked T waves — is a critical NCLEX recognition point.
Treatment follows three principles: stabilize the cardiac membrane (IV calcium gluconate), shift potassium into cells (insulin + glucose, sodium bicarbonate, albuterol), and remove potassium from the body (potassium binders, dialysis, loop diuretics).
Key Distinctions
Don't confuse hyperkalemia with hypokalemia symptoms. Hyperkalemia causes muscle weakness that can progress to flaccid paralysis, while hypokalemia also causes weakness but with additional cramping, decreased bowel sounds (paralytic ileus), and U waves on ECG.
Calcium gluconate does NOT lower potassium — it stabilizes the cardiac membrane to prevent fatal dysrhythmias while you use other interventions to actually lower the level. This is a common misconception tested on NCLEX.
Clinical Pearl
IV calcium gluconate is always the FIRST intervention in severe hyperkalemia with ECG changes — it acts within minutes to stabilize the heart. Then give insulin with glucose (insulin drives potassium into cells; glucose prevents hypoglycemia).
Knowledge Check
3 quick questions on the must-knows for this topic.
Question 1 of 3
What is the FIRST intervention in severe hyperkalemia with ECG changes?
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Go further
- SimulatorFluid & Electrolyte SimulatorChange one lab. Watch the whole patient respond. Sodium, potassium, calcium, magnesium, pH and volume, all linked — with a live ECG and an IV pole where every bag runs.
- GuideHyperkalemia ECG Changes in Order: Peaked T Waves to Sine Wave, and What the Nurse Does FirstThe fixed sequence — peaked T, long PR, wide QRS, sine wave — with approximate potassium levels, what IV calcium actually does (protects the heart, does not lower the potassium), the stabilize–shift–eliminate treatment order, and what the nurse monitors. Includes a live ECG you can drag.
- GuideHyperkalemia ECG Changes, Visualized: Peaked T Waves and Why Calcium Comes FirstWatch hyperkalemia’s ECG changes form, from peaked T waves to a widened QRS, then recall them. Why calcium protects the heart without lowering potassium, and the protect-shift-remove order.
- Commonly confusedHypokalemia vs HyperkalemiaLow vs high potassium — mirror-image ECG changes and interventions that must not be swapped.
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