AEIOU

Indications for Urgent Hemodialysis Mnemonic

Author: Maria Giulia Boemi, MD

Editor: Alyssa Haag, MD

Editor: Ian Mannarino MD, MBA

Editor: Kelsey LaFayette, DNP, ARNP, FNP-C

Illustrator: Abbey Richard, MSc

Modified: Jan 06, 2025

What is hemodialysis?

Hemodialysis is a form of renal replacement therapy in which a device assists the kidneys in maintaining homeostasis by removing excess fluid, solutes, and toxins from the blood. During hemodialysis, an intravenous line (IV) or an arteriovenous line (i.e., a connection between a small artery and vein), like an AV graft or AV fistula, is connected to a dialysis machine. The machine filters blood by using a semipermeable membrane between the blood and a dialysis solution, allowing solutes to move from greater to lesser concentrations. The dialysis solution is formulated so that excess fluid and solutes move from the blood to the solution to be discarded.

Hemodialysis is typically used to treat a rapid impairment of kidney function (i.e., acute kidney injury), a progressive loss of kidney function (i.e., chronic kidney disease), or the ingestion of certain toxic substances. It can be used short-term until the kidneys regain function or toxins are removed, long-term until a kidney transplant is available, or lifelong for individuals who are ineligible for renal transplantation.

An infographic detailing the mnemonic for indications for urgent hemodialysis, AEIOU.

What is AEIOU?

AEIOU is a mnemonic device used to help recall the urgent indications for hemodialysis.

What does the “A” in AEIOU mean?

The “A” stands for acidosis. While acidosis is typically defined as having a blood pH of less than 7.35, the indication for urgent dialysis is a blood pH of 7.15 or less. The kidneys play a role in excreting acid, and reabsorbing and synthesizing bicarbonate, or HCO₃, which is alkalotic or basic. In kidneys with decreased function, these processes can become impaired leading to metabolic acidosis. Hemodialysis can alter the concentration of bicarbonate in the blood to mitigate acidosis.

What does the “E” in AEIOU mean?

The “E” stands for electrolyte imbalances, which principally refers to high potassium levels in the blood (i.e., hyperkalemia). Hyperkalemia can alter the function of cells within the heart, and lead to life-threatening arrhythmias, or abnormal heart rhythms. Sources vary but note that potassium levels above 6-6.5 mEq/L indicate the need for hemodialysis, especially if accompanied by changes to an individual’s EKG. Hemodialysis can both alter the concentration of potassium (and other solutes) in the blood as well as correct acidosis, which contributes to hyperkalemia.

What does the “I” in AEIOU mean?

The “I” represents ingestion or overdose of certain substances or medications. In these instances, hemodialysis can be used to either remove the toxins or as supportive therapy to alleviate the effects of the toxin.

Of note, the acronym, I STUMBLED, can be used to recall the dialyzable substances:

“I” stands for isoniazid and isopropyl alcohol,
“S” stands for salicylates,
“T” stands for theophylline,
“U” stands for uremia,
“M” stands for methanol and metformin,
“B” stands for barbiturates,
“L” stands for lithium,
“E” stands for ethanol and ethylene glycol, and
“D” stands for Depakote (i.e., divalproex sodium) and dabigatran

What does the “O” in AEIOU mean?

The “O” stands for overload, which refers to volume overload. The inadequate excretion of fluids that may occur with renal impairment can lead to excess fluid and cause or exacerbate heart failure. Hemodialysis can remove large volumes of fluid and reduce excess fluid.

What does the “U” in AEIOU mean?

The “U” stands for uremia, or the accumulation of urea in the blood. This is indicated in laboratory studies by an increased level of blood urea nitrogen (BUN). Urea is a metabolic product formed from the breakdown of dietary and tissue proteins and is predominantly excreted by the kidneys. When urea excretion is impaired, blood levels rise and can cause platelet dysfunction and bleeding (i.e., uremic bleeding), inflammation of the pericardium (i.e., uremic pericarditis), and inflammation of brain tissue (i.e., uremic encephalitis). Therefore, the “U” may also stand for uremic pericarditis and uremic encephalitis.

What are the most important facts to know about the AEIOU mnemonic?

Hemodialysis is a device designed to help the kidneys remove fluid, solutes, and toxins from the blood. It is used in situations of impaired renal function or the ingestion of certain toxic substances or medications. The mnemonic “AEIOU” is used as a memory device to help recall the indications for urgent hemodialysis and stands for acidosis, electrolyte imbalance, ingestion or intoxication, overload of fluid, and uremia, respectively.

References

Hosten AO. BUN and Creatinine. Butterworths; 1990.

Kraut JA, Madias NE. Consequences and therapy of the metabolic acidosis of chronic kidney disease. Pediatr Nephrol. 2011;26(1):19-28. doi:10.1007/s00467-010-1564-4

King JD, Kern MH, Jaar BG. Extracorporeal removal of poisons and toxins. Clin J Am Soc Nephrol. 2019;14(9):1408-1415. doi:10.2215/cjn.02560319

Liu KD, Chertow GM. Dialysis in the Treatment of Kidney Failure. In: Loscalzo J, Fauci A, Kasper D, Hauser S, Longo D, Jameson J. eds. Harrison's Principles of Internal Medicine, 21e. McGraw-Hill Education; 2022. Accessed April 02, 2024

Malhotra A. Acute kidney injury (AKI). In: Geriatric Trauma and Acute Care Surgery. Springer International Publishing; 2018:367-380.

Osmosis: Dialysis care: Nursing. (2024, 6/24). Retrieved from (https://www.osmosis.org/learn/Dialysis_care:_Nursing).