UC-Irvine Internal Medicine Mini-Lecture Series Clinical Diagnosis and approach to HYPERKALEMIA

Objectives 1. Understand diagnosis of hyperkalemia based on clinical data 2. Understand ECG changes present in hyperkalemic states 3. Understand treatment/therapy approaches available for hyperkalemia

Clinical Scenario A 52-year-old man with hypertension and diabetes complains of weakness, nausea, and a general sense of illness, that has progressed slowly over 3 days. His medications include a sulonylurea, a diuretic, and an ACE inhibitor. On examination, he appears lethargic and ill. His BP is 154/105 mm Hg, HR 70bpm, temperature 98.6° F, and respiratory rate 22 breaths/min. The physical examination reveals moderate jugular venous distension, some minor bibasilar rales, and lower extremity edema. He is oriented to person and place but is able to give further history. The ECG shows a wide complex rhythm. Laboratory studies performed are significant for potassium 7.8 mEq/L, BUN is 114 mg/dL and creatinine is 10.5.

Diagnostics/Images: ECG Review: Peaked T-waves (V2-V5), widened QRS and prolonged PR interval resulting in (Sine-wave)- I, AvR, V1-V2 .

ECG Changes of Hyperkalemia Easily Distinguished ECG signs: peaked T wave. prolongation of the PR interval ST changes (which may mimic myocardial infarction) very wide QRS, which may progress to a sine wave pattern and asystole. Patients may have severe hyperkalemia with minimal ECG changes, and prominent ECG changes with mild hyperkalemia. Review: ECG changes of Hyperkalemia, may review back to ECG example in slide 5

Analysis Diagnosis: Hyperkalemia- Severe Classification of Hyperkalemia NORMAL: 3.5 to 5.0 mEq/L. MILD: 5.5 to 6.0 mEq/L SEVERE: Levels of 7.0 mEq/L or greater It is important to suspect this condition from the history and ECG, because laboratory test results may be delayed and the patient could die before those test results become available.

Therapy Approach BIG K Drop B - beta agonists, bicarbonate I - Insulin G - Glucose K - Kayexulate, Calcium D - Diuretics, Dialysis Review neumonic BIG K/Ca drop as a helpful tool to recall treatment options.

1st Line option Table of Pharmacological interventions summarized

Algorithm of Hyperkalemia treatment approach Reference: Hollander JC, Calvert CJ. Hyperkalemia. Am Fam Physician 2006; 73:283-90, Figure 2.

Clinical Pearls Symptoms of hyperkalemia are usually nonspecific, so risk factors must be used to suspect the diagnosis ECG changes consistent with hyperkalemia should be treated immediately as a life-threatening emergency. Do not await laboratory confirmation. Intravenous calcium is the antidote of choice for life-threatening arrhythmias related to hyperkalemia, but its effect is brief and additional agents must be used Highlight Points: Do not wait for laboratory values to initiate treatment for patient with suspected Hyperkalemia based on ECG or PE

Comprehension Questions QUESTION 1: A 55-year-old man presents in cardiac arrest. A dialysis fistula is present in the right arm. In addition to standard ACLS therapies, which of the following is most appropriate for this patient? A. 25 g of 50% dextrose, IV push. B. Sodium bicarbonate, 50-mL IV push. C. Begin immediate hemodialysis. D. Calcium gluconate, slow intravenous push. QUESTION 2: A 45-year-old man is brought into the emergency center due to significant dehydration and weakness. His potassium level is noted to be 7 mEq/L. Which of the following statements is most accurate regarding his potassium level? A. Hyperkalemia can usually be diagnosed by symptoms alone. B. An ECG showing peaked T waves means the patient is stable and treatment can safely wait until laboratory results are obtained. C. Hyperkalemia can mimic a myocardial infarction on the ECG. D. Hyperkalemia is synonymous with kidney disease. Answer Q1: Correct Answer: D. Explanation: Calcium is the only agent with rapid and reliable enough onset to potentially help this patient. Bicarbonate might be appropriate, but its onset is slower than calcium's and its effect is more disputed. Dialysis requires a hemodynamically stable patient. Answer Q2: Correct Answer: C. Explanation: The ST-segment and T-wave changes of hyperkalemia may mimic the ECG appearance of myocardial infarction. The nonspecific symptoms typical of hyperkalemia are also often seen in patients with MI, particularly elderly patients. Peaked T waves indicate that the heart is significantly affected by hyperkalemia and the patient should not be considered stable. Many conditions and medications may cause hyperkalemia, not just renal failure.

Comprehension Questions QUESTION 3: Which of the following statements regarding treatment of hyperkalemia in patients with some renal function is incorrect? A. Administration of normal saline may hasten the excretion of potassium. B. Administration of furosemide can hasten the excretion of potassium. C. The combination of saline with a diuretic is often indicated because hyperkalemic patients are frequently dehydrated. D. Patients with some renal function do not need dialysis even for severe hyperkalemia. QUESTION 4: A patient with severe renal disease is found to have hyperkalemia, with tall, peaked T waves on ECG. Vascular access cannot be readily obtained, but vital signs are stable. Which of the following would be appropriate temporizing measures? A. Inhaled albuterol 2.5 mg in 3 mL saline B. Oral sodium bicarbonate with rectal sodium polystyrene sulfonate C. Inhaled albuterol 20 mg, with oral or rectal sodium polystyrene sulfonate, 30 g D. Oral dextrose 25 g Answer Q3: Correct Answer: D. Explanation: Dialysis is definitive therapy for hyperkalemia. Patients who have some residual kidney function can sometimes be managed without resorting to dialysis, but it should always be available for those who fail to respond quickly. Answer Q4: Correct Answer: C. Explanation: High-dose inhaled albuterol (10-20 mg) can reliably lower serum potassium with reasonable safety. SPSS can remove potassium through the GI tract, but its effect is slow. Oral dextrose and oral bicarbonate have no role. Standard doses of albuterol have too slight an effect on potassium levels.

References Evans KJ, Greenberg A. Hyperkalemia: a review. J Intensive Care Med. 2005 Sep-Oct;20(5):272-290. Kamel KS, Wei C. Controversial issues in the treatment of hyperkalaemia. Nephrol Dial Transplant. 2003;18:2215-2218. Sood MM, Sood AR, Richardson R. Emergency management and commonly encountered outpatient scenarios in patients with hyperkalemia. Mayo Clin Proc. 2007 Dec; 82(12):1553-1561. Hollander JC, Calvert CJ. Hyperkalemia. Am Fam Physician 2006; 73:283-90