Study Notes on Technical Management of Hemodialysis Patients

Definition: Hemodialysis is a therapy that involves the removal of blood from a patient, passing it through an artificial kidney (dialyzer) for the removal of uremic toxins, and returning the treated blood to the patient.
Mechanism: The removal of toxins is achieved by diffusion across a semipermeable membrane in the dialyzer.
- Blood Side: Blood is circulated on one side of the membrane.
- Dialysate Side: Balanced electrolyte solution (dialysate) is circulated on the other side.
- Diffusion Process: Molecules move from high to low concentration through the membrane depending on their size.
Treatment Cycle: Blood circulates continuously throughout the dialysis treatment, typically lasting 4 to 5 hours, during Intermittent Hemodialysis (IHD).
Vascular Access: Achieved by placing a double-lumen catheter into the jugular vein.
Other Functions of Hemodialysis:
- Restores patient hydration via ultrafiltration.
- Restores electrolyte and acid-base balance through diffusion or convection.

Ultrafiltration: Removal of excess fluid achieved through negative pressure created by a pump on the dialysate side.
Intermittent Hemodialysis (IHD):
- Conducted 3 days a week during the maintenance phase.
Continuous Renal Replacement Therapies (CRRTs):
- Exploit concepts of diffusion and ultrafiltration and are performed continuously rather than intermittently.
Variability in Veterinary Practice: Increasing veterinary facilities provide extracorporeal therapies including IHD, CRRT, and hybrids.

Most commonly utilized for treating acute kidney injury (AKI) in veterinary medicine.
Standard Medical Therapy: First attempted before hemodialysis; some patients do not respond adequately.
Clinical Indicators:
- Anuria or oliguria in severe kidney injury cases.
- Life-threatening volume overload due to various medical interventions.
Need for Hemodialysis: Indicated when limited methods can remove extra fluid in anuric patients.

Severe Electrolyte or Acid-Base Disturbances
Life-threatening Volume Overload
Azotemia: Refractory to conventional management.
Chronic Kidney Disease
Toxicities and Drug Overdoses:
- Critical need to treat hyperkalemia and remove excess potassium when urine production is absent.
Uremic Signs: Conditional indications based on the progression of azotemia and treatment response.

Goals of Treatment: Provide supportive therapy until kidneys recover (weeks to months).
Possible Outcomes:
- Full renal recovery.
- Renal insufficiency but no longer needing dialysis.
- Life-long dialysis dependence.

Management: Hemodialysis to control symptoms when no chance of renal recovery exists; treatment during acute uremic crises similar to AKI.
Transition: Prolonged intermittent renal replacement therapy (PIRRT) or CRRT to IHD as patient stabilizes.

Criteria for Effective Removal: Substance must be sufficiently small and not protein-bound.
Examples of Treatable Substances:
- Antifreeze (ethylene glycol), alcohol, and digoxin.
Superiority of IHD versus CRRT: IHD more efficient due to rapid diffusion rates.

Operator Contact: Extended contact necessary for proper patient care and treatment efficacy.
Patient Behavior: Aggressive patients pose risks for both staff and themselves, potentially compromising treatment.
Physical Size: Challenges in treating pets weighing less than 2.5 kg due to low blood volume; priming volume considerations crucial.

Types: Models from established manufacturers (e.g., Gambro, Fresenius) are adapted from human use.
Common Features of Machines:
- Display screens show operational information and alarm conditions.
- Dialysate Proportioning System: Mixing purified water with preparing solutions.
Safety Monitoring Systems: Sensors monitor pressure, blood leaks, and potential air issues in the circuit.

Essential for creating safe hemodialysis conditions.
Components:
- Mixing valves, sediment filters, carbon tanks, reverse osmosis systems.
- Daily monitoring of water quality is necessary for patient safety.

Comprises the blood cartridge, tubing, and dialyzer. Designed for single-use, facilitating maximum efficiency.
Dialyzer Characteristics: Hollow fiber design for better waste product clearance; choice of natural versus synthetic membranes.

Double-Lumen Catheters: Inserted into jugular veins, providing dual pathways for blood removal and return.
Temporary vs Permanent: Temporary (nontunneled) versus permanent (tunneled) catheters based on length of use and risk factors.

Assess vital parameters (blood pressure, heart rate, etc.) and prepare the dialysis catheter as per established protocol.

Hypotension: Commonly due to fluid balance issues; solutions include adjusting ultrafiltration rates.
Dialysis Disequilibrium Syndrome (DDS): Rare but serious; treatment involves osmotic adjustments.
Hemorrhage Risks: Requires careful anticoagulation management to avoid excessive bleeding.

Infection Risks: Maintain strict aseptic practices; watch for signs of local/systemic infection.
Systemic Complications: Include edema, malnutrition, aluminum toxicity, and anemia, necessitating holistic patient management.

Survival Rates: 40%–60% of patients survive; outcomes vary based on cause and treatment responsiveness.
Long-Term Kidney Function: Some regain normal renal function, while others may need chronic management solutions.

Hemodialysis is a critical intervention for patients with significant renal dysfunction.
Requires expertise and rigorous monitoring to manage complex patient needs effectively.
Offers a potentially life-saving alternative to euthanasia, improving patient quality of life when renal recovery is limited.