This entry is not intended to supersede medical direction, protocols, standing orders or guidelines. Review of this material does not give an individual the right to practice medicine.

What is hyperkalemia?

Hyperkalemia, according to Tintanalli’s Emergency Medicine, is defined as a measured serum potassium [K+] of >5.5 mEq/L (Cline, et al, 2020). There is a little bit of discrepancy on this numerical value depending on the source that you look at; some texts state that the value is >5.0 mEq/L. Hyperkalemia is widely recognized as the electrolyte imbalance that has the greatest likelihood of causing life-threatening events. 

It is crucial to understand that there are varying degrees to hyperkalemia, which are categorized as:

  • Mild
  • Moderate 
  • Severe

In addition to understanding the different categories of hyperkalemia, it is also important to understand that these different ranges can be present in a patient that lives like this on a daily basis and can appear, generally, asymptomatic. One of the consistent schools of thought in relation to the treatment of hyperkalemia is to not get so focused in on the numerical value and focus more on the severity of symptoms based on the rate of change in the potassium value (Simon & Farrell, 2018). 

There are also a few important notes about epidemiology that should be mentioned:

  • Hyperkalemia occurs in less than 5% of the population; however, it is reported in approximately 10% of all patients admitted to a hospital (Simon & Farrell, 2018).
  • Moreover, the majority of patients that are diagnosed with hyperkalemia are male (Simon & Farell, 2018). 

What are the common causes of hyperkalemia?

There are a significant amount of causes for hyperkalemia; in fact, many different procedures that are performed in the ambulance, emergency department, or the intensive care unit can contribute to hyperkalemia. However, for the purpose of this blog, we are going to spend our time focusing on some of the more common presentations that prehospital providers will encounter. 

  • Causes of Hyperkalemia:
    • Acute Kidney Failure
    • Chronic Kidney Disease 
    • Metabolic acidosis 
    • Tissue necrosis
    • Rhabdomyolysis
    • Addison’s Disease
    • Severe burns
    • Diabetic Ketoacidosis (DKA)
    • Medications:
      • Adrenergic Blockers (Beta-blockers more traditionally)
      • ACE Inhibitors
      • Potassium-sparing diuretics
      • Chronic NSAID use
      • Digitalis toxicity

What are the normal potassium lab values?

Once again, the term “normal” should be used relatively loosely; there is still some area of debate that is associated with these stages. When in doubt, always refer to medical direction for appropriate lab values to base treatment on. Providers should be focused, primarily, on associated symptoms and the rate of change. 

  • Potassium Lab Values (Rossignol, et al, 2016):
    • 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: >8.0mEq/L

What are the signs and symptoms of hyperkalemia?

  • Skeletal muscle weakness
  • Decreased deep tendon reflex
  • Smooth-muscle hyperactivity; e.g. GI tract
  • Nausea
  • Abdominal cramping
  • Diarrhea

What diagnostic tools can be used in the prehospital setting to identify hyperkalemia?

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 out, both in the emergent and “non-emergent” parts of EMS systems wherein patients are being sent from urgent cares, free-standing emergency departments, or skilled nursing facilities. Often, these patients are sent with recurrent lab work that indicates rate of change and the actual values themselves. It is crucial for prehospital providers to well-versed in this!

What are some EKG manifestations of hyperkalemia?

  • Peaked T Waves
    • Narrow & Tall
    • Taller than 5mm in the Limb Leads
    • Taller than 10mm in the Precordial Leads
  • Flattened P Waves
  • Prolonged PR Interval
  • Widened QRS Complexes
  • Depressed ST Segment
  • Sine Waves
    • Broad QRS complex and tall T Wave
  • Heart blocks
  • Ventricular dysrhythmias
    • Remember that slower wide rhythms are often common with hyperkalemia; it is crucial to keep this on the list of differentials!
  • Asystole

What are some potential life threats that hyperkalemia can cause?

There is a significant correlation between serious dysrythmias and a serum potassium level of around 7.0mEq/l (Willis, 2020). One thing to take into consideration, though, is that not all patients are built the same or have the same tolerance for increased potassium levels.

What are some practical prehospital treatment modalities for hyperkalemia?

  • Calcium
    • Stabilizes the cardiac membrane and reduces myocardial irritability.
  • Albuterol
    • Assists with the movement of potassium from the extracellular space into the intracellular space.
  • Sodium Bicarbonate
    • Assists with acidosis associated with hyperkalemia.
    • Assists with the movement of potassium from the extracellular to the intracellular space.

When should a paramedic consider treating hyperkalemia?

There are many different schools of thought surrounding when or when not to treat hyperkalemia in the emergency department setting, let alone in the prehospital setting. In a recent podcast done by ERcast, Rob Orman, MD and his guest Britt Long, MD, discuss when they would advocate treatment. The criteria that they discussed for treatment was a notable shift from baseline to a hyperkalemia associated finding on the patient’s EKG, or a potassium level greater than 6.5mm/L (Orman & Long, 2018).

Special Considerations

What about the arrested hyperkalemia patient? We have all learned in the ACLS guidelines that at some point that we should consider the “H’s and T’s” that have caused that patient to arrest. Let’s take a quick look at a case where a patient with a great story for hyperkalemia descends into cardiac arrest.

A wide, fast, regular rhythm does not always equate to ventricular tachycardia. It is incredibly important to remember that hyperkalemia can be a ventricular tachycardia mimic. Certain medications that are used to traditionally treat ventricular tachycardia, such as amiodarone in this case, can lose effectiveness in the presence of hyperkalemia (Akiyama, Tomizawa, Umezawa, & Morishima, 1999). 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 doing standard ACLS.

References

  • Akiyama, J. I., Tomizawa, T., Umezawa, S., & Morishima, A. (1999). Hyperkalemia Probably Reverses the Antiarrhythmic Effects of Amiodarone. Japanese circulation journal63(4), 323-325.
  • Cline, D., Ma, O. J., Meckler, G. D., Stapczynski, J. S., Thomas, S. H., Tintinalli, J. E., & Yealy, D. M. (2020). Tintinallis emergency medicine: a comprehensive study  guide. New York: McGraw-Hill Education.
  • Orman, R., MD, & Long, B., MD. (2018, November 7). Re: Evidence Based Hyperkalemia Management [Web log comment]. Retrieved from https://www.hippoed.com/em/ercast/episode/novemberercast/evidencebased
  • Rossignol, P., Legrand, M., Kosiborod, M., Hollenberg, S. M., Peacock, W. F., Emmett, M., … & Gayat, E. (2016). Emergency management of severe hyperkalemia: guideline for best practice and opportunities for the future. Pharmacological research, 113, 585-591.
  • Simon, L. V., & Farrell, M. W. (2018). Hyperkalemia. In StatPearls [Internet]. StatPearls Publishing.
  • Willis, L. M. (2020). Fluids & electrolytes made incredibly easy! Philadelphia: Wolters Kluwer.