Prehospital identification and management of hyperkalemia – JEMS : EMS, Emergency Medical Services

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Gina Bartlett reviews hyperkalemia, a rare medical emergency that EMS providers should know how to manage.

Script

You are requested to respond to a residence for a woman found unconscious. The patient’s son is on the scene and tells the rush that his mother is “out of it and not responding appropriately”.

When you arrive on the scene, you find the patient lying in her bed covered in feces. The patient has a GCS of 10 and is sensitive to painful stimuli. His medical history includes Addison’s disease, colon cancer, stroke and brain tumor. When you check the patient’s blood sugar, it is within normal limits. All four patient leads have sinus tachycardia. Radial pulses are absent and automatic and manual blood pressures are impossible to obtain. A 12-lead ECG is performed and is unremarkable. The patient does not have veins suitable for venous access, so an IO is placed in the left tibia and flushed with 40 mg lidocaine to numb the area. A one liter bag of fluid is infused under pressure and the patient is moved to the stretcher. She then becomes numb.

You load her into the back of the ambulance and begin to brew a dose of epinephrine in an attempt to raise her blood pressure when your partner says, “Take a look at her EKG – something has changed. You notice a sine wave pattern and the patient’s heart rate has dropped to 70 beats per minute. You ask your partner to drive the emergency to the hospital while you call a doctor for a medical consultation. He tells you he is concerned about hyperkalemia and asks you to slowly administer one gram of calcium chloride through the IO. After hanging up with the physician, the patient’s rhythm changes to asystole on the monitor and the carotid pulse is no longer present. CPR is initiated when you arrive in the ambulance bay. Care is transferred to the receiving facility and you wonder what happened to your patient.

Hyperkalemia

Potassium is an incredibly important ion in the human body. It is an electrolyte that helps in the functioning of our nerves and muscles.1 It also helps regulate the electrical activity of our heart and maintain normal fluid levels.1 It is mainly intracellular and this property is maintained by the sodium-potassium pump.2 Changes in extracellular potassium levels, no matter how small, can have significant effects on the cardiovascular and neuromuscular systems, potentially leading to hyperkalemia.

Related

Hyperkalemia is defined as “a measured serum potassium of 5.0 mEq/L.3 It can be classified as mild, moderate or severe.3 Normal potassium levels are between 3.5 and 5.1 mEq/L.4 Mild hyperkalemia corresponds to potassium levels between 5.2 and 5.9 mEq/L, moderate hyperkalemia is 6.0 to 7.0 mEq/L and severe hyperkalemia is considered greater than 7 .0 mEq/L.4 Typically, most patients can live at one of these three levels and still be asymptomatic.3 When symptomatic, a patient may complain of the following symptoms: generalized fatigue, weakness, paresthesia, paralysis, and palpitations.2 In patients with severe hyperkalemia, palpitations, shortness of breath, chest pain, nausea or vomiting may occur.5 If left untreated, severe hyperkalemia can cause ventricular fibrillation or asystole, leading to cardiac arrest.4

Hyperkalemia has several different causes. One cause is decreased or impaired potassium excretion. This insufficiency is observed in patients with acute or chronic renal failure, sickle cell disease, Addison’s disease and systemic lupus erythematosus.2 Another cause is excess potassium in the intracellular space, which can be caused by potassium supplements, rhabdomyolysis, and hemolysis.2 Additionally, the transmembrane shifts that occur during acidosis and medications such as beta-blockers and succinylcholine can lead to hyperkalemia.2 Finally, crush syndrome can cause hyperkalemia in trauma patients. Crush syndrome occurs when toxins are released from crushed muscle tissue.6 The onset of symptoms is usually delayed four to six hours, but can occur as early as 60 minutes after the incident.6 Crush syndrome can ultimately lead to kidney failure, causing the damaged cells to excrete potassium and leading to hyperkalemia.6 Identifying this electrolyte imbalance in the prehospital setting is difficult but possible if the prehospital care provider knows what to look for.

Identification

The signs and symptoms of hyperkalemia are not unique to this condition, which can make it difficult for the prehospital care provider to identify. However, one major tool the provider has at their disposal is the 12-lead electrocardiogram.

EKG changes are not uncommon in hyperkalemic patients, especially as their potassium levels continue to rise. These changes occur due to the effect of increased potassium on myocytes in the heart.seven Peaking T waves, widening of the QRS complex, prolonged PR interval, bradycardia, first degree AV block, and a sinus pattern are all signs of hyperkalemia.4 Some changes, such as wide QRS, bradycardia, T wave spikes, and first degree AV block, are more common in severely hyperkalemic patients.4 Peak T waves are considered the first sign that the patient’s potassium level might be high.4 A wide QRS complex is the most common ECG change in these patients.4 Once a patient’s potassium level exceeds 8.0 mEq/L, the electrocardiogram changes to the sinusoidal pattern.seven

Management

Although mild hyperkalemia is not usually life threatening, severe hyperkalemia is and should be treated as such. Treatment in the prehospital setting isn’t as aggressive as it would be in the emergency department, but for some patients it could mean the difference between life and death.

The goal when treating the hyperkalemic patient is to reverse the transmembrane shift that has occurred due to excess potassium. EMS vendors carry three pharmacological agents that may work: calcium chloride, albuterol, and sodium bicarbonate.3 These medications will stabilize the patient while being transported to the receiving facility.

Calcium chloride “stabilizes the cardiac membrane and reduces myocardial irritability”.3 It acts quickly and is considered the first line treatment when severe hyperkalaemia is suspected.2 As mentioned earlier, hyperkalemia can have a negative influence on the myocytes of the heart, which is why it is important to try to stabilize these cells.

Albuterol is a beta-adrenergic agonist and acts to reverse transmembrane displacement by increasing plasma insulin concentration.2.3 In hyperkalemic patients, it is important to give a dose that is two to four times the typical amount that would be given to respiratory patients.2

Sodium bicarbonate is an alkalizing agent and is beneficial for these patients as it can help fight acidosis.3 It also helps reverse transmembrane shift by neutralizing hydrogen ions and increasing pH.2.3

Although none of these drugs are the final treatment for hyperkalemia, they will have a positive impact on the patient and stabilize him long enough to allow him to seek definitive care.

Conclusion

Although hyperkalemia is not a common medical emergency encountered by most providers, it is important to know what it is, how to identify it, and how to manage it. The 12-lead ECG has proven to be an excellent diagnostic tool for this condition. It is also important to know that certain illnesses or injuries can increase the risk of hyperkalemia. All of this information, in addition to medical command doctors, can work to provide a field diagnosis of hyperkalemia. Treatment will be given sooner and for some patients this could be the difference between life and death.

References

1. US National Library of Medicine. (2021, November 19). Potassium. MedlinePlus. Retrieved March 28, 2022, from https://medlineplus.gov/potassium.html

2. Garth, D. (2021, July 22). Treatment and management of hyperkalemia in emergency medicine: pre-hospital care, emergency care, consultations. Treatment and management of hyperkalaemia in emergency medicine: pre-hospital care, emergency care, consultations. Retrieved February 25, 2022, from https://emedicine.medscape.com/article/766479-treatment

3. Barrow, M. (2020, September). EMS treatment of hyperkalemia. EMS world. Retrieved February 25, 2022, from https://www.hmpgloballearningnetwork.com/site/emsworld/article/1224770/ems-treatment-hyperkalemia

4. Varga, C., Kálmán, Z., Szakáil, A., Drubits, K., Koch, M., Bánhegyi, R., Oláh, T., Pozsgai, É., Fülöp, N., & Bethlehem, J. (2019). ECG alterations suggestive of hyperkalaemia in normokalaemic patients… BMC Emergency Medicine. Retrieved February 25, 2022, from https://bmcemergmed.biomedcentral.com/track/pdf/10.1186/s12873-019-0247-0.pdf

5. What is hyperkalemia? National Kidney Foundation. (2022, March 7). Retrieved March 28, 2022, from https://www.kidney.org/atoz/content/what-hyperkalemia

6. Parrish, A., Tagore, A., Ariyaprakai, N., Hohbein, JL, DiCorpo, JE and Merlin, MA (2021, August 31). Managing the release of toxic chemicals that occurs during a crush injury – jems: EMS, emergency medical services – training, paramedic, EMT News. JEMS. Retrieved March 5, 2022, from https://www.jems.com/patient-care/trauma/managing-the-toxic-chemical-release-that-occurs-during-a-crush-injury/

7. Zaher, M., & Lafferty, J. (2009, July 7). Electrophysiological basis of electrocardiogram changes in hyperkalemia. HCP Live. Retrieved March 28, 2022, from https://www.hcplive.com/view/electrophysiologic_basis

8. Lederer, E. (2021, October 17). What are typical ECG findings in severe hyperkalemia (high serum potassium levels)? Breaking medical news, clinical trials, guidelines – Today on Medscape. Retrieved February 25, 2022, from https://www.medscape.com/answers/240903-11015/what-are-the-typical-ecg-findings-in-severe-hyperkalemia-high-serum-potassium-levels

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