REBEL EM – Emergency Medicine Blog

REBEL Core Cast 125.0 – Hyperkalemia

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Take Home Points

  • Always obtain an EKG in patients with ESRD upon presentation
  • Always obtain an EKG in patients with hyperkalemia as pseudohyperkalemia is the number one cause
  • If the patient with hyperkalemia is unstable or has significant EKG changes (wide QRS, sine wave) rapidly administer calcium salts
  • In patients who are anuric, early mobilization of dialysis resources is critical

    • REBEL Core Cast 125.0 – Hyperkalemia

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    Definition: A serum potassium level > 5.5 mmol/L

    Epidemiology

    • Common electrolyte disorder
    • 10% of hospitalized patients (Elliott 2010)

      • Causes

      • Pseudohyperkalemia: extravascular hemolysis
      • Renal failure (potassium is primarily eliminated by the kidneys)
      • Acidosis
      • Massive cell death (tumor lysis syndrome, rhabdomyolysis, burns, crush injuries, hemolysis)
      • Drugs: ACEI, ARBs, Spironalactone, NSAIDs, Succinycholine

        • Clinical Manifestations

        • Mild hyperkalemia often asymptomatic
        • Cardiac Effects
          • Increased potassium raises the resting membrane potential of cardiac myocytes
          • Slows ventricular conduction
          • Decreases length of action potential
          • Increases cardiac myocyte excitability
          • Cardiac effects can manifest in lethal dysrhythmias
          • Neuromuscular Effects
            • Paresthesias
            • Weakness
            • Flaccid paralysis
            • Depressed or absent deep tendon reflexes

              • Diagnosis

              • Suspect hyperkalemia in ALL patients with renal impairment, especially end-stage renal disease (ESRD)
              • Serum potassium
                • Can be artificially elevated by extravascular hemolysis
                • Blood gas results may differ from standard metabolic panels by up to 0.5mmol/L
                • 12-Lead EKG
                  • Screening test that can rapidly detect severe cardiac manifestations of hyperkalemia
                  • A normal EKG with a significant serum potassium elevation should raise concerns for spurious results (extravascular hemolysis)
                  • Sensitivity of EKG to detect hyperkalemia is poor (Wrenn 1991, Aslam 2002, Montague 2008)
                  • Classic EKG findings
                    • PR prolongation
                    • Peaked T waves
                    • Loss of P waves
                    • Widening of QRS complex
                    • Sine wave
                    • Ventricular Fibrillation
                    • Asystole
                    • Note: Hyperkalemia can present with a number of “non-classic” EKG findings including AV blocks and sinus bradycardia (Mattu 2000)
                    • Note: Hyperkalemic EKG changes do not necessarily occur in order (i.e. patients can jump from peaked T waves to sine wave)

                      • Management

                      Basics: ABCs, IV, O2, Cardiac Monitor and, 12-lead EKG

                      • Identify + treat underlying cause of hyperkalemia (i.e. rhabdomyolysis -> hydration)
                      • Remove inciting factors (i.e. stop ACEI, NSAIDs etc)

                        • Asymptomatic Patients without EKG Changes

                        • Eliminate potassium from the body
                          • Binding agents (SPS, Sodium zirconium cyclosilicate etc)
                          • Enhance renal elimination
                            • Intravenous hydration if volume depleted
                            • Consider potassium wasting loop diuretics (i.e. furosemide)
                            • Dialysis for anuric patients (i.e. ESRD)

                              • Symptomatic Patients or Significant EKG Changes

                              • Stabilize cardiac myocytes with calcium salts
                                • Mechanism: Recreates the electrical gradient leading to rapid reversal of cardiac effects and rapid stabilization
                                • Two Options: CaGluconate, CaCl2
                                  • No difference in time to onset (1st pass metabolism is a myth)
                                  • Dose: 1 ampule CaCl2 (270 mg Ca2+) = 3 ampules CaGluconate (90 mg Ca2+/ampule)
                                  • Onset of action: seconds to minutes
                                  • Duration: 20-30 minutes
                                  • Shift potassium into intracellular space (temporary)
                                    • Insulin (Moussavi 2021)
                                      • Mechanism: Activation of the Na-K-ATPase
                                      • Dose: 5-10 units IV
                                      • Onset of Action: < 15 min
                                      • Effect: Lowers potassium by about 0.6 mmol
                                      • Duration of action: 30-60 min
                                      • Give with dextrose (0.5 – 1 g/kg) unless hyperglycemia present
                                      • Caution: Duration of action of insulin may outlast administered dextrose. Be vigilant for hypoglycemia
                                      • Beta-adrenoreceptor agonists (i.e. albuterol)
                                        • Mechanism: Activation of beta receptors
                                        • Dose: 10-20 mg inhaled (4-8 standard ampules)
                                        • Onset of Action: < 15 min
                                        • Effect: Lowers potassium by about 0.6 mmol
                                        • Duration of action: 30-60 min
                                        • Additive effect with insulin (Allon 1990)
                                        • Note: Unlikely to have effect in patients taking beta-adrenoreceptor blocker medications
                                        • Sodium Bicarbonate (NaHCO3)
                                          • Evidence for the efficacy of NaHCO3 to lower serum potassium is scant and contradictory (Elliott 2010, Weisberg 2008)
                                          • Eliminate potassium from the body (see above)

                                            • Asymptomatic Patients with Minor EKG Changes

                                            • Minimal recommendations on managing this clinical entity
                                            • Eliminate potassium from the body (see above)
                                            • Consider calcium salt administration: patients can rapidly progress through EKG changes and calcium administration may prevent this from occurring. However, the effects of calcium are temporary and offer no long-term protection
                                            • Consider medications to shift potassium intracellularly while waiting for elimination

                                              • Take Home Points

                                              • Always obtain an EKG in patients with ESRD upon presentation
                                              • Always obtain an EKG in patients with hyperkalemia as pseudohyperkalemia is the number one cause
                                              • If the patient with hyperkalemia is unstable or has significant EKG changes (wide QRS, sine wave) rapidly administer calcium salts
                                              • In patients who are anuric, early mobilization of dialysis resources is critical

                                                • References

                                                Elliott MJ et al. Management of patients with acute hyperkalemia. CMAJ 2010; 182(15): 1631-5. PMID: 20855477

                                                Wrenn K et al. The ability of physicians to predict hyperkalemia from the ECG. Ann Emerg Med 1991; 20(11): 1229-32. PMID: 1952310

                                                Aslam S et al. Electrocardiography is unreliable in detecting potentially lethal hyperkalaemia in hemodialysis patients. Nephrol Dial Transplant 2002; 17: 1639-42. PMID: 12198216

                                                Montague BT et al. Retrospective review of the frequency of ECG changes in hyperkalemia. Clin J Am Soc Nephrol 2008; 3:324–330. PMID: 18235147

                                                Mattu A et al. Electrocardiographic manifestations of hyperkalemia. Am J Emerg Med 2000; 18: 721-9. PMID: 11043630

                                                Allon M, Copkney C. Albuterol and insulin for treatment of hyperkalemia in hemodialysis patients. Kidney Int 1990; 38:869–872. PMID: 2266671

                                                Weisberg LS. Management of hyperkalemia. Crit Care Med 2008; 36: 3246-51. PMID: 18936701

                                                Moussavi K et al. Reduced alternative insulin dosing in hyperkalemia: a meta-analysis of effects on hypoglycemia and potassium reduction. Pharmacotherapy 2021; 41(7): 598-607. PMID: 33993515

                                                Post Peer Reviewed By: Salim R. Rezaie, MD (Twitter/X: @srrezaie)

                                                The post REBEL Core Cast 125.0 – Hyperkalemia appeared first on REBEL EM - Emergency Medicine Blog.

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                                                REBEL EM – Emergency Medicine BlogBy Salim R. Rezaie, MD