Info
🌱 來自: Huppert’s Notes
DialysisAccess🚧 施工中
Dialysis/Access
Types of dialysis
• Hemodialysis (HD):
- Blood is pumped along a semipermeable membrane across which electrolytes, water, and toxins are removed by diffusion into another fluid being pumped along the other side of the membrane (dialysate). The composition of the dialysate solution and a number of dialysis specifications are adjusted to meet individual clearance needs.
- Water is filtered across the membrane by pressure
- Usually performed over 2–4 hours, three times per week in a dialysis center
- Pros: Frequent contact with providers, can be initiated emergently
- Cons: Hypotension, circuit needs anticoagulation, need vascular access
• Continuous renal replacement therapy (CRRT):
- Continuous venovenous hemodialysis (CVVHD) is dialysis performed continuously
- Indicated for hemodynamically unstable patients requiring dialysis, e.g., patients requiring pressors
- Only performed in the ICU
• Peritoneal dialysis (PD):
- Peritoneum used as semipermeable membrane for removal of water and toxins from the blood via diffusion into intraperitoneal dialysate
- Pros: Performed at home, “gentler” fluid and electrolyte shifts
- Cons: Increased risk of hyperglycemia, peritonitis and catheter-associated infections; several contraindications related to abdominal anatomy
Indications for dialysis
• Acute indications for dialysis: “AEIOU”
- Acidosis
- Electrolytes (e.g., hyperkalemia)
- Intoxication (e.g., methanol, lithium, ASA, ethylene glycol)
- Volume Overload
- Uremia
• Indications for dialysis in CKD:
- Development of signs and symptoms of uremia, especially malnutrition
- Complications of CKD that become refractory to medical management
Dialysis access
• Arteriovenous fistula (preferred): Needs 3–4 months to mature after placement; lowest infectious risk
• Arteriovenous graft: Typically needs 1 month to mature, although newer grafts can be accessed in 2 to 3 days; moderate infectious risk
• Central venous catheter: Can access immediately after placement, may be a temporary catheter or a permanent tunneled dialysis catheter placed by IR; highest infectious risk
• Peritoneal dialysis catheters:
- Placed by general surgery, IR, or interventional nephrology laparoscopically
- Ideally allow 2 weeks for surgical wound healing at catheter placement site to avoid dialysate leaks from peritoneal cavity; however, “urgent start peritoneal dialysis” can be initiated with low volume, supine exchanges for patients requiring dialysis sooner to avoid a temporary venous dialysis catheter placement
- Need to start off with low volumes then increase slowly over 1–2 months to full prescription
Renal transplant
• Transplant referral: Usually consider when eGFR is between 20 and 30 mL/min/1.73 m2
- Evaluation includes months-long extensive biopsychosocial assessment
- Transplant is generally contraindicated if there is concern for limited medical prognosis or ability to adhere to medical treatment
- Waiting time for living and deceased donor transplants ranges from 1–5 yr depending on the region (USRDS Annual Report 2019)