Overview
Definition:
Hyperkalemia is defined as a serum potassium level greater than 5.0-5.5 mEq/L in children, which can be life-threatening due to its effects on cardiac electrophysiology
In the emergency department, rapid intervention is crucial to prevent arrhythmias and cardiac arrest.
Epidemiology:
While less common in healthy children, hyperkalemia is a significant concern in pediatric patients with renal insufficiency, certain genetic disorders, burns, or those receiving specific medications
Premature infants and neonates are at higher risk due to immature renal function.
Clinical Significance:
Severe hyperkalemia can lead to life-threatening cardiac arrhythmias, including bradycardia, widening QRS complexes, and sine wave patterns on ECG, potentially progressing to ventricular fibrillation and asystole
Prompt recognition and management are vital for patient survival and preventing neurological sequelae.
Clinical Presentation
Symptoms:
Often asymptomatic until severe
Muscle weakness progressing to paralysis
Palpitations
Nausea and vomiting
Shortness of breath
Confusion.
Signs:
Cardiac: bradycardia, irregular pulse, hypotension, ECG changes (peaked T waves, flattened P waves, prolonged PR, widened QRS, sine wave)
Neurologic: lethargy, weakness
Respiratory: slow, shallow breathing.
Diagnostic Criteria:
Serum potassium > 5.0-5.5 mEq/L
ECG changes suggestive of hyperkalemia (e.g., peaked T waves, widened QRS complex) are critical for immediate assessment and guiding therapy, even before laboratory confirmation in a critical patient.
Diagnostic Approach
History Taking:
Recent illness (e.g., diarrhea, dehydration)
Known renal disease or dysfunction
Use of nephrotoxic medications (e.g., ACE inhibitors, ARBs, potassium-sparing diuretics)
Intake of high-potassium foods or supplements
Congenital anomalies
History of rhabdomyolysis or hemolysis.
Physical Examination:
Assess vital signs (heart rate, blood pressure, respiratory rate)
Perform a thorough cardiac auscultation for murmurs or arrhythmias
Evaluate for signs of dehydration or volume overload
Assess neurologic status for weakness or altered mentation
Examine for edema or skin changes.
Investigations:
Serum electrolytes (including potassium, sodium, chloride, bicarbonate, BUN, creatinine)
ECG is paramount for assessing cardiac risk
Complete blood count (CBC) to rule out hemolysis
Urinalysis to assess renal function and identify potential causes
Arterial or venous blood gas (ABG/VBG) for acid-base status and bicarbonate
Consider CK levels if rhabdomyolysis is suspected.
Differential Diagnosis:
Pseudohyperkalemia (hemolysis during blood draw, leukocytosis, thrombocytosis)
Renal failure
Hemolysis
Rhabdomyolysis
Acidosis
Adrenal insufficiency
Medications causing potassium retention
Tumor lysis syndrome.
Management
Initial Management:
Stabilization of the cardiac membrane with intravenous calcium is the first-line emergency treatment to counteract the cardiotoxic effects of hyperkalemia
Simultaneously, initiate measures to shift potassium intracellularly and promote its excretion.
Medical Management:
1
Calcium Administration: Calcium gluconate 10% (0.5-1 mL/kg IV over 5-10 minutes) or Calcium chloride 10% (0.2-0.4 mL/kg IV over 5-10 minutes)
Repeat doses as needed based on ECG changes
2
Potassium Shifting Agents: Insulin (0.1 units/kg regular insulin IV bolus followed by 0.1 units/kg/hr infusion) with glucose (0.5-1 g/kg of 50% dextrose IV bolus to prevent hypoglycemia)
Albuterol (salbutamol) nebulization (2.5-5 mg in saline nebulized over 10-15 minutes)
Sodium bicarbonate (1-2 mEq/kg IV) if significant acidosis is present
3
Potassium Excretion: Loop diuretics (e.g., furosemide 1 mg/kg IV if renal function permits)
Potassium binders (e.g., sodium polystyrene sulfonate - Kayexalate, 1 g/kg PO/rectally, onset is slow and may cause GI complications).
Surgical Management:
Renal replacement therapy (dialysis) is the definitive treatment for severe or refractory hyperkalemia, especially in patients with significant renal dysfunction
This is usually initiated after initial medical stabilization in the ED.
Supportive Care:
Continuous cardiac monitoring (ECG)
Frequent reassessment of vital signs and potassium levels
Fluid management to ensure adequate hydration and renal perfusion
Correction of acidosis
Monitoring for hypoglycemia if insulin/dextrose therapy is used
Strict intake and output monitoring.
Complications
Early Complications:
Cardiac arrhythmias (bradycardia, heart block, ventricular fibrillation, asystole)
Cardiac arrest
Seizures
Muscle paralysis affecting respiratory muscles.
Late Complications:
Neurologic deficits if severe hypoxemia occurs due to cardiac arrest
Electrolyte imbalances during recovery
Complications related to dialysis if initiated
Recurrence of hyperkalemia if underlying cause is not addressed.
Prevention Strategies:
Careful monitoring of potassium levels in at-risk pediatric patients
Judicious use of medications that can cause hyperkalemia
Prompt management of conditions leading to hyperkalemia (e.g., renal failure, acidosis)
Educating caregivers about dietary restrictions for potassium-rich foods if applicable.
Prognosis
Factors Affecting Prognosis:
Severity of hyperkalemia (serum potassium level)
Presence and severity of ECG changes
Speed of diagnosis and initiation of treatment
Underlying cause of hyperkalemia
Renal function
Presence of comorbidities.
Outcomes:
With prompt and appropriate management, including cardiac stabilization with calcium and intracellular shifting of potassium, the prognosis for acute hyperkalemia is generally good
Patients can recover fully if cardiac arrest is averted and the underlying cause is treated
Long-term prognosis depends heavily on the cause and degree of renal involvement.
Follow Up:
Close monitoring of serum electrolytes and renal function is required
If hyperkalemia was due to a reversible cause, follow-up aims to ensure resolution
For chronic conditions leading to hyperkalemia (e.g., renal disease), ongoing management and regular laboratory checks are essential
Education on dietary management and medication adherence is critical.
Key Points
Exam Focus:
Always remember the three crucial steps in acute hyperkalemia management: 1
Membrane stabilization (Calcium)
2
Intracellular shift (Insulin/Glucose, Albuterol, Bicarb)
3
Potassium excretion (Diuretics, Binders, Dialysis)
DNB/NEET SS exams often test this sequence and the indications for each agent.
Clinical Pearls:
In a pediatric emergency, if ECG changes are concerning for hyperkalemia, administer calcium empirically even before serum potassium levels are back, especially if the patient is unstable
Rapid infusion of insulin/glucose can cause hypoglycemia
monitor blood glucose closely
Albuterol is effective but can cause tachycardia and tremors.
Common Mistakes:
Forgetting to administer calcium first in cases of severe ECG changes
Administering insulin without adequate glucose replacement leading to dangerous hypoglycemia
Over-reliance on potassium binders in acute settings due to their slow onset
Failing to address the underlying cause of hyperkalemia, leading to recurrence.