EMS Treatment of Hyperkalemia

By the definition of Tintinalli’s Emergency Medicine, hyperkalemia is a measured serum potassium of more than 5.5 mEq/L.¹ There is a bit of discrepancy to  this value; some texts cite it as 5.0 mEq/L. Either way, hyperkalemia is widely recognized as the electrolyte imbalance with the greatest likelihood of causing life-threatening events. 

Hyperkalemia is categorized as mild, moderate, or severe, but understand these different levels can all be present in patients who live with hyperkalemia on a daily basis and can appear generally asymptomatic. A consistent school of thought in treating hyperkalemia is to focus less on the numerical value and more on the severity of symptoms based on the change rate of the potassium value.²  

A few epidemiological notes to mention: Hyperkalemia occurs in less than 5% of the population; however, it is reported in approximately 10% of all patients admitted to hospitals.² Moreover, the majority of patients diagnosed with hyperkalemia are male.²

Normal Potassium Values

When in doubt, always refer to medical direction for appropriate lab values on which to base treatment. Providers should focus primarily on these patients’ associated symptoms and rate of change. 

Stages of hyperkalemia and their potassium lab values:³

• Normal potassium levels: 3.5–5.5 mEq/L
• Mild hyperkalemia: 5.5–6.5 mEq/L
• Moderate hyperkalemia: 6.5–8.0 mEq/L
• Severe hyperkalemia: more than 8.0 mEq/L

There are a significant number of causes for hyperkalemia; many different procedures performed in the ambulance, emergency department, or intensive care unit can contribute to it. However, note also that specific medical conditions can act as a precursor to hyperkalemia. Some of the more common on which prehospital education tends to focus are renal in nature, such as acute kidney failure, chronic kidney disease, and muscle breakdown leading to rhabdomyolysis. 

There are several other conditions that can lead to hyperkalemia, like metabolic acidosis, Addison’s disease, severe burns, and diabetic ketoacidosis. Different medication classes can also increase the risk of development: adrenergic blockers (beta blockers, more traditionally), ACE inhibitors, potassium-sparing diuretics, NSAIDs used chronically, and digitalis toxicity. 

Signs and Symptoms 

One of the difficulties in spotting hyperkalemia is the list of general symptoms that can be attached to it. Most can be associated with many other disease processes. Coupled with that, often EMS providers do not have definitive labs to confirm their suspicions, meaning electrolyte abnormalities may be excluded from the list of potential problems considered. EMS providers must take the patient’s history and medication use into consideration while assessing signs and symptoms. These symptoms can include general skeletal muscle weakness, decreased deep tendon reflexes, smooth-muscle hyperactivity (especially in the GI tract), nausea, abdominal cramping, and diarrhea. 

One of the best ways to detect hyperkalemia is through use of a 12-lead EKG. As a point of contention, though, one of the most commonly taught ways to confirm hyperkalemia, peaked T-waves, may come with less clinical significance than we were once inclined to believe. In fact, peaked T-waves are often not associated with life-threatening potassium levels but should tip off a provider that potassium levels are on the rise.⁴ Below is a list of EKG findings consistent with hyperkalemia:

• Peaked T-waves
  • Narrow and tall
  • Taller than 5 mm in the limb leads
  • Taller than 10 mm in the precordial leads
• Flattened P-waves
  • Widening of P-waves prior to their disappearance
  • The lack of P-waves can result in the appearance of a junctional rhythm 
• Prolonged PR Interval
• Widened QRS complexes
• Depressed ST-segment
• Sine waves
  • Broad QRS complex and tall T-wave
• AV blocks
• Ventricular dysrhythmias
  • Remember that slower wide rhythms are often common with hyperkalemia—keep this on the list of differentials!
• Asystole.

There is a significant correlation between serious dysrhythmias and a serum potassium level of around 7.0 mEq/L.⁵ These dysrhythmias are often in the form of AV blocks, wide-complex tachycardia that can mimic and lead to ventricular dysrhythmias, and ultimately asystole. One thing to consider, though, is that not all patients are built the same or have the same tolerance for increased potassium levels. 

Diagnosis and Treatment

Why spend all this time focusing on lab values when not every prehospital agency uses point-of-care lab testing? There are many calls that come, in both the emergent and nonemergent parts of EMS systems, where patients are transported from urgent cares, freestanding emergency departments, and skilled nursing facilities. Often these patients are sent with recurrent lab work that indicates actual values and their rate of change. It is crucial for prehospital providers to be well-versed in this!

While hospital teams can utilize a bevy of options to treat hyperkalemia, EMS providers can often be limited in their tools. There are three distinct pharmacological agents to which EMS providers can turn: calcium, albuterol, and sodium bicarbonate. The goal of intervention in hyperkalemia is to stabilize the body at the cellular level, move potassium from the extracellular space to the intracellular space, and ultimately excrete potassium from the body. None of these drugs are the ultimate treatment for hyperkalemia; however, it is important to understand how each of them works in preparing for excretion from the body. 

Calcium, whether chloride or gluconate, stabilizes the cardiac membrane and reduces myocardial irritability. Albuterol is a beta-adrenergic agonist that assists with the movement of potassium from the extracellular space into the intracellular space. (It is important to note that nebulized albuterol in the prehospital setting is typically given in 2.5–5.0-mg aliquots, but in hyperkalemia should be given in a heftier dose—around 10–20 mg). Lastly, there is sodium bicarbonate. While there is substantial evidence to limit the routine use of sodium bicarbonate in out-of-hospital cardiac arrest and diabetic ketoacidosis, there is benefit in giving it in hyperkalemia. Sodium bicarbonate assists with acidosis and the movement of potassium from the extracellular to the intracellular space. 

Special Considerations

What about the arrested hyperkalemia patient? We’ve all learned in the ACLS guidelines to consider the “Hs and Ts” that can cause patients to arrest. 

A wide, fast, regular rhythm does not always equate to ventricular tachycardia. Remember that hyperkalemia can be a v-tach mimic. Certain medications traditionally used to treat ventricular tachycardia, such as amiodarone, can lose effectiveness in the presence of hyperkalemia.⁶ In cases where we have a great story for hyperkalemia, it is potentially beneficial to start resuscitation with the thought of treating hyperkalemia prior to standard ACLS.  

References

1. Tintinalli JE, Ma OJ, Yealy DM, Meckler GD, Stapczynski JS, Cline DM, Thomas SH. Tintinalli's Emergency Medicine: A Comprehensive Study Guide. New York: McGraw-Hill, 2020.

2. Simon LV, Hashmi MF, Farrell MW. Hyperkalemia. StatPearls [Internet], 2019 Dec 10; www.ncbi.nlm.nih.gov/books/NBK470284/.

3. Rossignol P, Legrand M, Kosiborod M, et al. Emergency Management of Severe Hyperkalemia: Guideline for Best Practice and Opportunities for the Future. Pharmacol Res, 2016 Nov; 113(Pt A): 585–91.

4. Hippo Education. Hyperkalemia Management, Lupus, Wegener’s, EM MIndset, Iron, Red Anus, www.hippoed.com/em/ercast/episode/novemberercast/evidencebased.

5. Willis LM. Fluids & Electrolytes Made Incredibly Easy! Philadelphia: Wolters Kluwer, 2020.

6. Akiyama J, Tomizawa T, Umezawa S, Morishima A. Hyperkalemia Probably Reverses the Antiarrhythmic Effects of Amiodarone: A Case Report. Jpn Circ J, 1999 Apr; 63(4): 323–5.

Mike Barrow is the primary instructor for a paramedic program in Colorado Springs, Colo. He has completed his BS in healthcare administration and is currently pursuing a master’s degree in public health. Mike has been involved in several prehospital FOAM projects, including the CPR Podcast and, currently, The Prehospital Review.