EKG in hyperkalemia

Q: Which of the following is the earlier sign of hyperkalemia? (select one)

A) disappearance of P wave 

B) tall peaked T waves

Answer: B

The effect of potassium on EKG is progressive and can help a clinician to take preemptive actions. EKG usually changes in hyperkalemia in the following order.

• Tall peaked T waves with a shortened QT interval (earliest sign)
• progressive lengthening of the PR interval and QRS duration
• disappearance of P wave
• widening of QRS complex
• sine wave
• ventricular standstill (asystole)

Said that clinician needs to be aware of the pitfall that the progression and severity of EKG changes do not correlate, and other factors highly effect the EKG changes (very common in ICU and renal patients) like hypocalcemia, acid/base imbalance, and hyponatremia.

#cardiology

References:

1. Montague BT, Ouellette JR, Buller GK. Retrospective review of the frequency of ECG changes in hyperkalemia. Clin J Am Soc Nephrol 2008; 3:324.

2. Aslam S, Friedman EA, Ifudu O. Electrocardiography is unreliable in detecting potentially lethal hyperkalaemia in haemodialysis patients. Nephrol Dial Transplant 2002; 17:1639.

3. Montague BT, Ouellette JR, Buller GK. Retrospective review of the frequency of ECG changes in hyperkalemia. Clin J Am Soc Nephrol. 2008 Mar;3(2):324-30. doi: 10.2215/CJN.04611007. Epub 2008 Jan 30. PMID: 18235147; PMCID: PMC2390954.