Management of Peaked T Waves on EKG in Overdose Patient
In a patient with peaked T waves on EKG following an overdose, hyperkalemia should be immediately suspected and treated as a life-threatening emergency requiring rapid intervention to prevent cardiac arrest.
Primary Concern: Hyperkalemia
Peaked T waves (tenting) are often the first electrocardiographic manifestation of hyperkalemia, which is one of the few potentially lethal electrolyte disturbances that can rapidly progress to cardiac arrest 1. In the setting of an overdose, this finding requires immediate attention as it may indicate severe hyperkalemia that can quickly deteriorate to more dangerous cardiac rhythms.
ECG Progression in Hyperkalemia
The ECG changes in hyperkalemia typically follow a predictable pattern:
- Peaked T waves (earliest sign)
- Flattened or absent P waves
- Prolonged PR interval
- Widened QRS complex
- Deepened S waves
- Merging of S and T waves
- Sine-wave pattern
- Idioventricular rhythms
- Asystolic cardiac arrest
If left untreated, these changes can rapidly progress to life-threatening arrhythmias and cardiac arrest 1.
Management Algorithm
1. Immediate Assessment
- Obtain stat serum potassium level
- Continuous cardiac monitoring
- Check for other ECG abnormalities (QRS widening, PR prolongation, absent P waves)
- Assess for symptoms of hyperkalemia (muscle weakness, paresthesias, respiratory difficulties)
2. Immediate Treatment (in order of urgency)
A. Stabilize Myocardial Cell Membrane
- Calcium chloride (10%): 5-10 mL (500-1000 mg) IV over 2-5 minutes OR
- Calcium gluconate (10%): 15-30 mL IV over 2-5 minutes
- This protects the heart from the effects of hyperkalemia by antagonizing potassium's effect on cardiac membranes 1
- ECG monitoring during administration is recommended 2
B. Shift Potassium into Cells
- Insulin and glucose: 10 units regular insulin with 25g (50 mL of D50) IV over 15-30 minutes
- Sodium bicarbonate: 50 mEq IV over 5 minutes
- Nebulized albuterol: 10-20 mg nebulized over 15 minutes
C. Promote Potassium Excretion
- Diuresis: Furosemide 40-80 mg IV
- Potassium binders: Sodium polystyrene sulfonate (Kayexalate) 15-50g orally or rectally
- Dialysis: Consider in severe cases, especially with renal failure or if other measures fail
3. Identify and Address the Cause of Hyperkalemia
In overdose patients, consider:
- Medications that can cause hyperkalemia
- Rhabdomyolysis from drug-induced muscle breakdown
- Renal failure (acute or chronic)
- Acidosis
- Tissue trauma
Special Considerations in Overdose Setting
Multiple drug involvement: Many overdoses involve multiple substances that may affect potassium levels or cardiac conduction 1.
QT interval monitoring: Some overdoses (particularly antipsychotics, antidepressants) may cause QT prolongation, which requires additional monitoring 1.
Rebound hyperkalemia: Monitor potassium levels frequently as temporary shifting treatments wear off, especially in patients with impaired renal function 1.
Acidosis: Drug overdoses may cause metabolic acidosis, which can worsen hyperkalemia 1.
Monitoring and Follow-up
- Repeat ECG after initial treatment to assess response
- Monitor serum potassium levels every 2-4 hours until stable
- Continue cardiac monitoring until potassium normalizes and ECG changes resolve
- Consider ICU admission for patients with severe hyperkalemia (K+ >6.5 mmol/L) or significant ECG changes 1
Pitfalls to Avoid
Delayed recognition: Peaked T waves may be subtle but represent an early warning sign of potentially lethal hyperkalemia 1, 3.
Overreliance on symptoms: Patients may be asymptomatic despite dangerous potassium levels 1.
Calcium administration with digoxin toxicity: Use calcium with caution in patients who may have taken cardiac glycosides, as it may worsen digoxin toxicity 2.
Inadequate monitoring: Treatments that shift potassium are temporary, and rebound hyperkalemia can occur if definitive treatment is not provided 1.
Assuming normal renal function: Many overdose patients may have acute kidney injury, limiting potassium excretion 1.
Peaked T waves in an overdose patient represent a medical emergency requiring prompt recognition and treatment to prevent progression to life-threatening arrhythmias and cardiac arrest.