Acute Kidney Injury (AKI)/Renal Failure

• AKI Definition: two different guidelines, both say similar things

PRIFLE: pediatric version adapted from adults. RIFLE is an acronym for Risk of renal dysfunction, Injury to the kidney, Failure of kidney function, Loss of kidney function, and End-stage Renal Disease

KDIGO: Increase in SCr by >/= 0.3mg/dl within 48h; or Increase in SCr>/=1.5x baseline, within the last 7 days; or UOP < 0.5 ml/kg/h for the last 6h

Renal Replacement Therapy/Dialysis

• Dialysis is the removal of solutes across a semi-permeable membrane down a concentration gradient

• Two mechanisms of dialysis:

  • • Diffusion- solutes down concentration gradient

    • Convection - osmotic force of water pushes solutes dissolved in it through a membrane (solvent drag)

• The "fluid" used in dialysis - dialysate - consists of highly purified water with sodium, potassium, magnesium, calcium, bicarbonate, chloride, and dextrose

• Concentration gradient is always maintained (equilibrium is never reached) because the dialysate is continuously flowing/replaced with new solution in the dialyzer

• The common indications for starting dialysis can be remembered with the mnemonic AEIOU

 A: Acidosis (metabolic acidosis refractory to other treatments)

 E: Electrolyte disturbances (typically hyperkalemia, but can be for other electrolytes)

 I: Ingestions/intoxications (salicylates, methanol, ethylene glycol, lithium, etc.)

 O: Overload  (significant fluid overload not improving with diuretics)

 U: Uremia (causing uremic encephalopathy or uremic pericarditis), usually BUN > 100

• Typically metals cannot be removed via dialysis. Molecules with large volumes of distribution, largely protein-bound, or large molecular weight are also not dialyzable.

• Remember medications will be dialzyable so important to check with Pharmacy about dosing and optimal timing of drugs 

• Types of Dialysis: 

  • • Peritoneal Dialysis

    • Intermittent Hemodialysis

    • Continuous Renal Replacement Therapy (CRRT)

Peritoneal Dialysis (PD)

• Toxins are removed out of the blood using the peritoneal membrane for diffusion. Fluid is instilled into the abdomen, allowed to  "dwell" a certain amount of time to allow diffusion to occur, and then removed. This process is referred to as a cycle. 

• This can be done manually or automatically with a machine

Intermittent Hemodialysis (HD)

• This is done with vascular access with a temporary vs permanent dialysis line (or a surgical fistula, uncommon in pediatrics)

• These are short sessions anywhere between 2-4 hours

• Ideal for long-term dialysis, toxin removal, hyperkalemia

• Problematic for hemodynamically unstable patients, acutely critically ill

• Complications: hypotension, air embolism, hemolysis, and disequilibrium syndrome 

  • • • Dialysis disequilibrium syndrome: This is more common in patients during or soon after their first treatment. It is a clinical syndrome characterized by neurologic deterioration, restlessness, mental confusion, headache, occasional muscle twitching, and coma.

• More basic overview information here

Diuretic Therapy

• Used for fluid overload, AKI, management of cardiac disease/heart failure

• Important to maintain accurae I/Os, minimize other IVF intake, and get daily weight on patients

• Monitoring electrolytes, including Phos, K, Ca, and Mg, are essential - discuss frequency with your team (see FEN/GI for more about this)