Morning Report

Morning Report: Hyperkalemia in ARF

Presented by Dr. T Horan.

HPI: 69 y.o. Female with a history of colon ca and glomerular nephritis who was recently DC from Colombia in NYC. Pt reports that since the DC 2 weeks ago she has have chest pain in the L lower chest associated with SOB, 6/10 comes and goes, non radiating increases with cough. Pt states that she has had decrease energy, and generalized weakness. Pt has a positive 45 pack year smoking history. Pt reports nausea but denies abdominal pain, vomiting, diarrhea, fever, headache or dizziness or dysuria. Pt has no history of blood clots. 

VS: BP146/62, HR 83, Temp 98.2, RR 18, Sp02 100%

EKG: NSR at 84 no STT changes, Peaked T waves

CXR: developing Pneumonia

WBC: 16.6, HGB: 9.1
GLU: 169, BUN 171, Creatinine 10.3, K 7.9, CO2 6, Na 137, Cl 118

ABG: pH 7.2 pCO2 18.3 bicarb 7

ED Course: ABG ordered, pt started on calcium, insulin, glucose and given bicarb.  Vascular surgery was called to place a HD access.  Emergent HD was started in the ICU.

Inpatient Course:  Pt tolerated HD well.  K improved to 5 after HD.  Pt continues to improve, ID was consulted in regards to possible pneumonia or lung mass.

Learning Points:

  1. Early recognition of hyperkalemia and acute renal failure.
  2. Early treatment of acute renal failure and hyperkalemia.

References: 

  • Tintinalli’s Emergency Medicine, Acute renal failure.
  • Smith, Mahoney. Emergency Interventions for Hyperkalaemia(Review). The Cochrane Colloboration 2009 Issue 3

Morning Report Discussion:

Pearls of Hyperkalemia in the ED.

Potassium is one of the major ions that used during the cardiac action potential.  Too much or too little potassium can greatly affect the conduction of the heart and thus have devastating effects on the rest of the body.  Classically one the early signs of hyperkalemia can be seen on EKG, in the form of diffuse peak T waves.  If the hyperkalemia is not discovered and addressed, the next EKG sign would be PR interval prolongation until the P wave flattens and disappears.  The next EKG sign would be widening of the QRS complex until the QRS and the T wave merge together.  Finally the EKG will move into ventricular fibrillation and asystole.  It is important to note that this progression of EKG changes is classic but does not always occur in a stepwise fashion.  Any change in the EKG with a patient suspected to have hyperkalemia demands immediate intervention.

The emergent intervention in a patient with EKG changes and hyperkalemia are targeted at restoring the tight balance of extracellular potassium in the body.  Calcium is used to help stabilize the myocardium but it does not lower the concentration of extracellular potassium.  When calcium is given to patients with hyperkalemia it moves the resting membrane potential closer to a normal resting membrane potential so that myocyte excitability can return to normal.  The effects of calcium occur in 1 to 3 minutes but do not last more than 60 minutes.  Calcium is only a temporizing measure in order to let other medications restore the potassium balance.  Ideally an increase in the excretion of potassium is desired but in an emergent case of hyperkalemia waiting for the body to excrete the potassium is not realistic.  In a patient with emergent hyperkalemia medication is given to drive potassium into the cell.  This is done by giving insulin which stimulates the Na / K ATPase which allows potassium to move into the cell against its concentration gradient.  Insulin is normally given with 50 mL of 50% dextrose so that the patient does not become hypoglycemic.  The dextrose does not affect insulin’s ability to stimulate the Na / K ATPase.  Insulin normally takes 10 to 20 minutes to take effect.  Sodium bicarbonate can also be used to shift potassium back into the cell.  It does this by increasing the blood pH.  The cells’ response to the increase in blood pH is to exchange extracellular potassium with intracellular hydrogen in order to balance the blood pH.  Albuterol is also gaining a role in patients with emergent hyperkalemia.  Catecholamines activate the Na / K ATPase through beta 2 receptor stimulation.  Nebulized Albuterol at high doses has an immediate effect on lowering extracellular potassium and lasted for up to 2 hours.  These medications are used to help restore the balance of potassium and can temporize the effects of hyperkalemia.  In the end the patient needs a way to increase the excretion of the potassium.  The most effective method of doing this is hemodialysis.

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