Show notes
Take Home PointsAlways obtain an EKG in patients with ESRD upon presentationAlways obtain an EKG in patients with hyperkalemia as pseudohyperkalemia is the number one causeIf the patient with hyperkalemia is unstable or has significant EKG changes (wide QRS, sine wave) rapidly administer calcium saltsIn patients who are anuric, early mobilization of dialysis resources is criticalREBEL Core Cast 125.0 – HyperkalemiaClick here for Direct Download of the Podcast.Definition: A serum potassium level > 5.5 mmol/LEpidemiologyCommon electrolyte disorder10% of hospitalized patients (Elliott 2010)CausesPseudohyperkalemia: extravascular hemolysisRenal failure (potassium is primarily eliminated by the kidneys)AcidosisMassive cell death (tumor lysis syndrome, rhabdomyolysis, burns, crush injuries, hemolysis)Drugs: ACEI, ARBs, Spironalactone, NSAIDs, SuccinycholineClinical ManifestationsMild hyperkalemia often asymptomaticCardiac EffectsIncreased potassium raises the resting membrane potential of cardiac myocytesSlows ventricular conductionDecreases length of action potentialIncreases cardiac myocyte excitabilityCardiac effects can manifest in lethal dysrhythmiasNeuromuscular EffectsParesthesiasWeaknessFlaccid paralysisDepressed or absent deep tendon reflexesDiagnosisSuspect hyperkalemia in ALL patients with renal impairment, especially end-stage renal disease (ESRD)Serum potassiumCan be artificially elevated by extravascular hemolysisBlood gas results may differ from standard metabolic panels by up to 0.5mmol/L12-Lead EKGScreening test that can rapidly detect severe cardiac manifestations of hyperkalemiaA 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 findingsPR prolongationPeaked T wavesLoss of P wavesWidening of QRS complexSine waveVentricular FibrillationAsystoleNote: 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)ManagementBasics: ABCs, IV, O2, Cardiac Monitor and, 12-lead EKGIdentify + treat underlying cause of hyperkalemia (i.e. rhabdomyolysis -> hydration)Remove inciting factors (i.e. stop ACEI, NSAIDs etc)Asymptomatic Patients without EKG ChangesEliminate potassium from the bodyBinding agents (SPS, Sodium zirconium cyclosilicate etc)Enhance renal eliminationIntravenous hydration if volume depletedConsider potassium wasting loop diuretics (i.e. furosemide)Dialysis for anuric patients (i.e. ESRD)Symptomatic Patients or Significant EKG ChangesStabilize cardiac myocytes with calcium saltsMechanism: Recreates the electrical gradient leading to rapid reversal of cardiac effects and rapid stabilizationTwo Options: CaGluconate, CaCl2No 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 minutesDuration: 20-30 minutesShift potassium into intracellular space (temporary)Insulin (Moussavi 2021)Mechanism: Activation of the Na-K-ATPaseDose: 5-10 units IVOnset of Action: < 15 minEffect: Lowers potassium by about 0.6 mmolDuration of action: 30-60 minGive with dextrose (0.5 – 1 g/kg) unless hyperglycemia presentCaution: Duration of action of insulin may outlast administered dextrose. Be vigilant for hypoglycemiaBeta-adrenoreceptor agonists (i.e. albuterol)Mechanism: Activation of beta receptorsDose: 10-20 mg inhaled (4-8 standard ampules)Onset of Action: < 15 minEffect: Lowers potassium by about 0.6 mmolDuration of action: 30-60 minAdditive effect with insulin (Allon 1990)Note: Unlikely to have effect in patients taking beta-adrenoreceptor blocker medicationsSodium 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 ChangesMinimal recommendations on managing this clinical entityEliminate 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 protectionConsider medications to shift potassium intracellularly while waiting for eliminationTake Home PointsAlways obtain an EKG in patients with ESRD upon presentationAlways obtain an EKG in patients with hyperkalemia as pseudohyperkalemia is the number one causeIf the patient with hyperkalemia is unstable or has significant EKG changes (wide QRS, sine wave) rapidly administer calcium saltsIn patients who are anuric, early mobilization of dialysis resources is criticalReferencesElliott MJ et al. Management of patients with acute hyperkalemia. CMAJ 2010; 182(15): 1631-5. PMID: 20855477Wrenn K et al. The ability of physicians to predict hyperkalemia from the ECG. Ann Emerg Med 1991; 20(11): 1229-32. PMID: 1952310Aslam S et al. Electrocardiography is unreliable in detecting potentially lethal hyperkalaemia in hemodialysis patients. Nephrol Dial Transplant 2002; 17: 1639-42. PMID: 12198216Montague BT et al. Retrospective review of the frequency of ECG changes in hyperkalemia. Clin J Am Soc Nephrol 2008; 3:324–330. PMID: 18235147Mattu A et al. Electrocardiographic manifestations of hyperkalemia. Am J Emerg Med 2000; 18: 721-9. PMID: 11043630Allon M, Copkney C. Albuterol and insulin for treatment of hyperkalemia in hemodialysis patients. Kidney Int 1990; 38:869–872. PMID: 2266671Weisberg LS. Management of hyperkalemia. Crit Care Med 2008; 36: 3246-51. PMID: 18936701Moussavi 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: 33993515Post 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.