Hyperkalemia Treatment

Overview

1. Stabilize the cardiac membrane (immediate)
2. Shift K+ into cells (temporary, buys time)
3. Remove K+ from the body (definitive)

Step 1 - Cardiac Membrane Stabilization

• Dose: 10 mL of 10% calcium gluconate IV over 1-3 minutes
• Does NOT lower K+ - it raises the threshold potential and counteracts the depolarizing effect on myocardial membranes
• Onset: near-immediate; duration: 30-60 minutes
• Repeat if no ECG improvement within 3-5 minutes
• Calcium chloride has more elemental calcium but is caustic if it extravasates peripherally - avoid in peripheral IV access
• Caution in digoxin toxicity: calcium potentiates digoxin cardiac effects

Step 2 - Transcellular Shift (Temporizing)

a. Insulin + Dextrose

• Fastest pharmacological method to lower plasma K+
• Dose: 10 units regular insulin IV + 50 mL D50W (1 amp) bolus, followed by D5W infusion at 100 mL/hr to prevent late hypoglycemia
• Onset: 15 minutes; peak effect up to 1 hour
• Watch for hypoglycemia, especially in renal failure (insulin half-life is prolonged; lispro/aspart may reduce this risk)
• If blood glucose >300 mg/dL (e.g., diabetic), can give insulin alone without dextrose
• Never give dextrose alone - hyperglycemia without insulin can paradoxically raise K+

b. Albuterol (beta-2 agonist)

• Dose: 20 mg nebulized over 10 minutes (much higher than asthma dose, as only a fraction is absorbed)
• Onset: ~30 minutes; effect additive to insulin
• IV albuterol (0.5 mg) is equivalent but not available in the US

c. Sodium Bicarbonate

• Promotes cellular K+ uptake and enhances renal K+ excretion
• Useful when metabolic acidosis is present (serum HCO3 <10 mmol/L)
• Limited role in patients without residual kidney function or in acute emergency
• Does NOT enhance the K+-lowering effect of insulin or albuterol
• Dose: 50-100 mEq IV over 10-20 minutes

Step 3 - Potassium Removal (Definitive)

a. Diuretics

• Loop diuretics (furosemide) + thiazides promote renal kaliuresis
• Effective only if adequate kidney function is present

b. Dialysis

• The most definitive treatment for severe hyperkalemia
• Indicated when kidney function is severely impaired (severe AKI or ESKD)
• Typically cannot be initiated fast enough to replace the above temporizing measures - use them first

c. Potassium-binding resins (for non-emergency / chronic use)

Nonemergent / Chronic Management

• Dietary K+ restriction and counseling; avoid salt substitutes (contain KCl)
• Discontinue offending drugs: ACE inhibitors, ARBs, potassium-sparing diuretics, NSAIDs, heparin, trimethoprim
• Loop diuretics when eGFR <30 mL/min
• Oral NaHCO3 if metabolic acidosis is present
• K+ binders (patiromer or SZC) allow continued use of RAASi when clinically needed
• Fludrocortisone if hyperkalemia is due to hypoaldosteronism

Quick Reference by ECG Finding

Recent Evidence (2025)

Anesthetic Management for Noncardiac Surgery in Cardiac Disease

1. Preoperative Cardiovascular Evaluation

Risk Assessment Framework (ACC/AHA)

• Unstable coronary syndromes (unstable angina, recent MI <60 days)
• Decompensated heart failure (NYHA Class IV)
• Significant arrhythmias (high-degree AV block, symptomatic VT, uncontrolled AF)
• Severe valvular disease (severe AS, symptomatic MS)

• Low risk (<1% MACE): superficial, endoscopy, cataract, breast surgery
• Elevated risk (>1%): intraperitoneal, intrathoracic, orthopedic, prostate, head/neck
• High risk: aortic/major vascular surgery

2. Preoperative Medication Management

• Beta-blockers: Continue perioperatively - abrupt withdrawal risks rebound ischemia and tachycardia
• Statins: Continue - may be cardioprotective
• Antiplatelets (aspirin): Continue unless bleeding risk outweighs cardiac risk; dual antiplatelet therapy management depends on coronary stent timing
• ACE inhibitors/ARBs: Controversial - may cause intraoperative hypotension; some clinicians hold the morning dose but this risks rebound hypertension; decision should be individualized
• Diuretics: May cause hypokalemia - check electrolytes preoperatively

3. Intraoperative Anesthetic Management (ACC/AHA Table 21-10)

Choice of Anesthetic Technique

Key Intraoperative Principles

• Avoid tachycardia (most important trigger for ischemia) - maintain HR <80 ideally
• Avoid hypertension and hypotension - both increase myocardial oxygen demand or reduce supply
• Avoid metabolic/respiratory acidosis
• Maintain normothermia

4. Monitoring

Standard + Advanced Monitoring

• Intraarterial pressure monitoring: Reasonable for severe CAD, major cardiac risk factors, or any procedure beyond minor surgery
• Central venous pressure: Useful in prolonged procedures with large fluid shifts
• Pulmonary artery catheter: May be considered when hemodynamics cannot be stabilized preoperatively; routine use NOT recommended (Class III, Level A)
• TEE: Reasonable for emergency use in hemodynamic instability during noncardiac surgery (IIa-C); routine intraoperative TEE during noncardiac surgery - not recommended (III: No Benefit)

ECG Monitoring

• Lead V5 detects ~75% of ischemic events; combination of II + V5 covers >90%
• Early ischemic changes: T-wave flattening or inversion
• Progressive: ST depression (subendocardial ischemia) or ST elevation (transmural ischemia)
• Hypertension + tachycardia are almost always the cause (not the result) of intraoperative ischemia

TEE for Ischemia Detection

• Regional wall motion abnormalities (RWMA) appear before ECG changes
• More sensitive early indicator than ECG
• Both regional and global abnormalities can also reflect changes in HR, preload, afterload, or drugs - not all RWMA = ischemia

5. Disease-Specific Management

A. Hypertensive Patients

• Continue antihypertensives up to surgery
• Elective surgery delay considered for sustained diastolic BP >110 mmHg
• Intraoperative: use depth of anesthesia and vasoactive drugs to control swings
• Postoperative: IV labetalol (hypertension + tachycardia); vasodilators if bradycardic

B. Ischemic Heart Disease (CAD)

• Maintain heart rate <80, MAP 60-80 mmHg
• Avoid succinylcholine if patient is digitalis-toxic (risk of arrhythmia)
• Treat intraoperative ischemia: increase O2 delivery (nitroglycerin for vasospasm), reduce demand (deepen anesthesia, beta-blocker if tachycardia, vasopressor if hypotension)
• Postoperative: continue monitoring, early re-ambulation, restart cardiac medications

C. Heart Failure

• Systolic HF: Avoid myocardial depressants; maintain preload/afterload; continue ACE-I/ARB, beta-blockers, diuretics perioperatively; watch for ACE-I-induced angioedema at intubation
• Diastolic HF: Maintain sinus rhythm, adequate filling time (avoid tachycardia), do not over-diurese
• BNP elevation preoperatively correlates with increased perioperative risk
• Optimize volume status before surgery

D. Hypertrophic Cardiomyopathy (HCM)

• Goal: minimize LVOT obstruction
• Maintain: adequate intravascular volume, normal/slow heart rate, increased SVR
• Avoid: vasodilation (reduces afterload - worsens obstruction), hypovolemia, tachycardia, inotropes
• Use beta-blockers; phenylephrine (pure alpha) preferred over ephedrine if vasopressor needed

E. Valvular Heart Disease

• Aortic Stenosis (severe): Maintain sinus rhythm, slow-normal HR, adequate preload; avoid vasodilation and hypotension (can be catastrophic); avoid spinal anesthesia
• Aortic Regurgitation: Avoid bradycardia (increases regurgitant volume); maintain slightly elevated HR; vasodilation is tolerated
• Mitral Stenosis: Maintain slow HR, sinus rhythm; avoid increases in pulmonary vascular resistance (hypoxia, hypercarbia, acidosis)
• Mitral Regurgitation: Slightly elevated HR; afterload reduction beneficial

6. Pacemakers and ICDs

• Identify device type, indication, and programming; consult cardiologist
• Obtain device information card from patient; call manufacturer if needed

• Use bipolar electrocautery whenever possible to minimize electromagnetic interference (EMI)
• Place grounding pad far from the device
• Pacemaker-dependent patients: reprogram to asynchronous mode (VOO/DOO) before surgery
• ICDs: Consider disabling antitachycardia therapy before surgery; apply external defibrillation pads and keep attached to defibrillator
• Limit cautery to short bursts
• Magnet application: disables ICD antitachycardia function but does NOT convert pacemaker to asynchronous mode in most ICDs (consult manufacturer)

• Interrogate device immediately after surgery to confirm all functions restored
• Monitor continuously until antitachycardia functions confirmed active

7. Arrhythmia Management

• Hemodynamic collapse: synchronized cardioversion
• Stable: adenosine (AV block, breaks reentry), beta-blockers, non-DHP calcium channel blockers
• WPW: use procainamide or ibutilide - avoid amiodarone, adenosine, digoxin, verapamil (Class III - risk of accelerated ventricular response)

8. Key 2024 Guideline Update

Revised Cardiac Risk Index (RCRI)

Background

The 6 Components - 1 Point Each

Risk Interpretation

Clinical threshold: Patients with ≥2 risk factors are considered elevated risk. Beta-blocker initiation (in currently untreated patients) should be considered several days before surgery in those with ≥3 RCRI points.

How to Calculate - Worked Example

Limitations

• Does not predict mortality - only cardiac morbidity
• Does not account for age as an independent variable
• Less accurate for vascular surgery patients (underestimates risk)
• Does not incorporate biomarkers (BNP/NT-proBNP), which the 2024 AHA/ACC guidelines now recommend as supplementary predictors
• The Gupta MICA calculator (derived from ACS NSQIP data) is an alternative that adds ASA class and age, and may be more accurate in some settings

Clinical Use in Guidelines (2024 Update)

• NT-proBNP/BNP - preoperative elevation is an independent predictor of MACE and should be measured in high-risk patients
• ACS NSQIP calculator as an acceptable alternative/supplement

Perioperative Antiplatelet Management in High-RCRI Patients

• Continuing antiplatelet therapy → increased surgical bleeding
• Stopping antiplatelet therapy → stent thrombosis, MI, stroke

Decision Framework - Coronary Stent Patients

1. Timing of Surgery After Stent Implantation

The 2022 ESC guidelines updated these intervals to account for newer-generation DES, which have lower in-stent thrombosis rates than first-generation devices. PCI performed for ACS carries higher perioperative risk than elective PCI, even at the same time interval after implantation.

2. What to Do with Aspirin (Monotherapy or Part of DAPT)

• Intracranial, spinal canal, or posterior eye surgery (bleeding in a closed space is catastrophic)
• Very high surgical bleeding risk where even aspirin is prohibitive - always a multidisciplinary decision

3. What to Do with P2Y12 Inhibitors (Clopidogrel, Prasugrel, Ticagrelor)

Hold times before surgery (to allow platelet function recovery):

When to hold:

• Surgery requires stopping the P2Y12 inhibitor (most major surgeries)
• Patient is beyond the minimum DAPT duration for their stent type
• Plan: continue aspirin, stop P2Y12, restart P2Y12 as soon as possible after surgery (within 24-48 hours ideally)

When to continue DAPT:

• Surgery does not require stopping P2Y12 inhibitors (minor procedures, dental extractions with local hemostasis)
• Within the mandatory DAPT window and surgery cannot be delayed

4. Bridging Therapy - Heparin is NOT an Option

• Heparin and LMWH do not substitute for antiplatelet protection against stent thrombosis
• Heparin can paradoxically increase platelet aggregation
• Neither ACC/AHA nor ESC guidelines recommend heparin bridging for antiplatelet therapy discontinuation

What about GP IIb/IIIa inhibitors or IV P2Y12 agents?

• IV reversible glycoprotein IIb/IIIa inhibitors (tirofiban, eptifibatide) - short half-life, can be stopped 4-8 hours before surgery
• IV reversible P2Y12 inhibitor (cangrelor) - half-life ~3-5 minutes, discontinued 1 hour before surgery

5. Key Principles for Non-Stent High-RCRI Patients (Aspirin Only)

6. Multidisciplinary Decision-Making

• Anesthesiologist
• Surgeon
• Cardiologist/interventional cardiologist

7. Postoperative Monitoring

• Serial troponin measurement in high-RCRI patients postoperatively (watch for perioperative myocardial injury, MINS)
• Restart P2Y12 inhibitor as soon as hemostasis is confirmed - delay increases stent thrombosis risk
• Any suspected stent thrombosis: emergent PCI is the treatment of choice

Summary Algorithm

High-RCRI patient → has coronary stent?
  │
  YES → When was stent placed?
  │      ├─ <30 days → Delay elective surgery; if urgent, maintain DAPT + interventional cardiology on standby
  │      ├─ 30 days-6 months (DES) → Weigh risk of delay vs. stent thrombosis; if must proceed: continue aspirin, hold P2Y12 (5-7 days), restart ASAP
  │      └─ >6 months (DES) or >30 days (BMS) → Continue aspirin; hold P2Y12 5-7 days before; restart ASAP after surgery
  │
  NO → Continue aspirin if secondary prevention; hold only for high-bleeding-risk surgery
       Do NOT bridge with heparin