Nephrology/Urology Program

What can hemodialysis treat?

• The most common indication for hemodialysis is acute kidney injury.  Patients refractory to medical therapy, as well as oligoanuric patients, are candidates for hemodialysis.
  
  Electrolyte disturbances, such as hyperkalemia, can be managed with hemodialysis very quickly and effectively.  
  
  Chronic kidney disease can also be managed with hemodialysis (typically a four-hour session two or three times a week). Cost, however, can be a limiting factor that prevents most clients from pursuing this option for lifetime management.  
  
  Hemodialysis is often utilized in cats for stabilization prior to kidney transplantation.  
  
  Ultrafiltration therapy is a method to remove excessive fluid accumulation in patients with iatrogenic fluid overload (often seen with oligoanuric acute kidney injury) or congestive heart failure.

What is hemoperfusion?

• Hemoperfusion is performed to help remove certain toxins from blood.  Large toxins or those with strong protein binding are unable to be removed across the filter during hemodialysis; therefore a charcoal cartridge is used to purify the patient’s blood.  This therapy can be quite effective for various intoxications, most commonly NSAIDs.

What other toxicities can be treated with hemodialysis?

• Ethylene glycol toxicity can be devastating. Animals who become azotemic have a poor to grave prognosis.  Dialysis can be performed to support them while azotemic, but it may take three months or more before renal function returns (if at all). 
• However, ethylene glycol is very efficiently dialyzed, and nearly all ethylene glycol can be removed from the patient’s blood within one dialysis treatment. Patients who have been exposed to ethylene glycol, but have not yet become azotemic should be referred for hemodialysis immediately. 
• Dialysis may remove the toxin in one treatment, thereby preventing renal damage from ever occurring. 
• The nephrotoxin found within lily plants is unknown; however it is thought to be removed via hemodialysis.  Because of the grave prognosis once a cat has become azotemic after lily intoxication, hemodialysis should be considered in patients who have been exposed, however have not yet become azotemic. 
• It has not yet been determined if the nephrotoxic component of grapes, raisins, and currants is dialyzable.

How long will my animal require hemodialysis?

• The duration of dialysis therapy is quite variable.  Many toxins (such as ethylene glycol, lily ingestion, etc.) can be removed with a single treatment. 
• Oligoanuric patients with acute kidney injury may only require one to three treatments until they become polyuric, thus often allowing the reintroduction of traditional management. 
• Patients with severe kidney injury may require weeks to months to regain kidney function.  Dialysis is initially performed on an inpatient basis, then patients are transitioned to outpatient dialysis when stable.

What is the prognosis for patients requiring hemodialysis?

• The survival for acute kidney injury patients treated with hemodialysis is approximately 50 percent, however there is a wide variability in mortality. 
• Infectious etiologies (leptospirosis, pyelonephritis) have upwards of 90 percent survival, whereas toxicity (azotemic ethylene glycol or lily) is closer to 10-40 percent. 
• While 50 percent overall survival may sound poor, remember that nearly 100 percent of these patients have already failed medical therapy.