So I’m going to keep this post short & sweet. Today my preceptor and myself ran through a really interesting case about hyperkalemia (elevated blood potassium). Interestingly one of the potential urgent treatments was dialysis. Did I remember this? Yes. Did I remember all the other potential cases for urgently dialyzing someone? Nope. But you bet your arse I do now thanks to the mnemonic AEIOU. For starters there are two main types of dialysis: One is peritoneal dialysis where a patient uses the lining of their own abdominal cavity as a filter. The other more common type is hemodialysis. This process extracts blood from a person, mechanically filtered through a large machine before being returning it back to them. Most dialysis treatments are by appointments however there are exceptions where urgent dialysis for an acutely ill patient is warranted:
- Acidosis: Human blood has a normal pH range between 7.35-7.45. If there is either an acute loss of negative charge (base/anion) and/or the addition of an acid (H+), the pH will become acidic. If the pH drops below 7.1 then studies suggest urgent dialysis is indicated.
- Electrolytes: The normal potassium concentration ranges from 3.5-5mEq/L. However if K+ increases above that the patient is at significant risk of developing lethal cardiac arrhythmias. For this reason refractory hyperkalemia >6.5 may require dialysis.
- Intoxication: remember SLIME:
- salicylate (aspirin)
- lithium (bipolar medication)
- isopropanol (rubbing alcohol)
- methanol (wood alcohol)
- ethylene glycol (antifreeze)
- Overload: If a patient has a weak heart, too much fluid can be a deadly thing. Since their pump already struggles to push their normal fluid load forward, any additional fluid (work) strains the heart too much resulting in a backlog and classic symptoms (leg swelling and pulmonary congestion). For this reason, diuretics such as Lasix or Spironolactone are typically given to help pee off excess fluid. However, when this fails, dialysis can be used.
- Uremia: Urea is a toxic byproduct normally produced by the human body. When it becomes too high (indicated as an elevated BUN, or blood urea nitrogen (normal 7-20 mg/dL)) it causes an array of symptomatology such as mental status changes, peripheral nerve problems, significant nausea & vomiting, pericarditis, skin itching and/or frosting and can even produce the smell of urine on ones breath.
This list is probably not all inclusive, but if asked what the major causes for acute hemodialysis in the future, at least you’ll remember the big ones. 😉
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