Hyperkalemia

An 80yo with history of HTN, dyslipidemia, CAD, s/p CABG on lisinopril, furosemide, potassium and spironolactone was admitted due to syncope. BP  systolic 70's PR 80 RR 18 and O2 sat 95 at 5L O2. Patient is lethargic with dry oral mucosa, clear breath sounds, regular cardiac rhythm and no murmur, flat, soft abdomen, no pedal edema.This is the ECG.

Figure 1 - 12L ECG

The 12L ECG revealed a regular wide QRS rhythm, tall T waves and the P waves are difficult to discern. The QRS and T wave segment seemed to merge or having a "sine" wave pattern. 

Laboratory work-up revealed creatinine of 3, BUN 62, bicarb 12 and K of 8. Patient was hydrated and NaHCO3, D50 and insulin, kayexalate were given. So, this patient has hyperkalemia from acute renal failure probable from diuretics (and patient was on ACEI and K supplement)

Progressive hyperkalemia produce distinctive sequence of events affecting the QRS (depolarization) and ST=T segments (repolarization). The normal serum potassium is between 3.5 and 5 mEq/L. The changes would be narrowing and peakng of the T waves ("tented" and "pinched" shape). Further potassium elevation will make P waves small and may disappear entirely. Continued elevation will produce intraventricular conduction delay (widening of the QRS), sine-wave pattern and asystole.

Reference:

Goldberger A. 2013. Goldberger’s Clinical Electrocardiography : A Simplified Approach 8Ed. Ph Elsevier

#307