NephrologyTier 2Topic

Indications for acute and chronic dialysis

Two different decisions

Two entirely different decisions:
- Acute - a life-threatening derangement that will not respond to medical therapy in time
- Chronic - a symptom- and quality-of-life-driven decision, made over months, with an alternative (conservative care)
*No creatinine, urea or eGFR value by itself is an indication for dialysis*

~5-10% of AKI requires acute RRT; >50% of stage 3 AKI in ICU
~2,900 Australians start kidney replacement therapy each year (ANZDATA); median age at start ~60
~20% start with a functioning permanent access; the rest start with a catheter - a marker of late referral

Dialysis removes small solutes and water only; the indication is always about a solute or volume problem, not the diagnosis
Uraemic toxicity is caused by retained middle molecules, guanidines and protein-bound solutes - urea is a marker, not the toxin
The threshold for dialysis is symptomatic, because uraemic symptoms appear at very different eGFR levels in different people (muscle mass, nutrition, comorbidity)

Acute indications - AEIOU

	Indication
A	Acidosis - metabolic acidosis refractory to bicarbonate, pH <7.1
E	Electrolytes - hyperkalaemia refractory to medical therapy, or with ECG changes
I	Intoxication - lithium, salicylate, methanol, ethylene glycol, metformin (lactic acidosis), theophylline, valproate
O	Overload - pulmonary oedema unresponsive to diuretics
U	Uraemia - pericarditis, encephalopathy, seizures, uraemic bleeding, intractable nausea and vomiting

Timing: early ('pre-emptive') initiation does NOT improve survival - STARRT-AKI, AKIKI, ELAIN
- Wait for a true indication; watchful waiting avoids dialysis altogether in a substantial minority
Also consider in: tumour lysis with refractory hyperkalaemia/hyperphosphataemia, severe hypercalcaemia, hyperthermia, hypothermia

Symptoms, not a number
- Uraemic symptoms: nausea, vomiting, anorexia, weight loss, fatigue, pruritus, restless legs, cognitive slowing
- Refractory volume overload or hypertension
- Refractory hyperkalaemia or acidosis
- Malnutrition/declining nutritional status despite dietary intervention
- Pericarditis, encephalopathy, neuropathy - late and should never be reached
Usually occurs at eGFR 5-10 mL/min/1.73m2
*IDEAL trial: starting at eGFR 10-14 vs 5-7 gave no survival or quality-of-life benefit* - so start on symptoms
Prepare at eGFR ~20, or KFRE 2-yr kidney failure risk >10%

Modality selection - the axis is lifestyle and comorbidity, not clearance

	Haemodialysis	Peritoneal dialysis
Schedule	4-5 h, 3x/week (in-centre or home)	Daily; CAPD 4 exchanges or APD overnight
Suits	No home support, needs supervision, obesity, prior abdominal surgery	Independence, travel, work, preserving residual function, needle phobia, poor cardiac reserve
Haemodynamics	Intermittent, hypotension-prone	Gentle, continuous
Residual function	Declines faster	Better preserved
Diet/fluid	Tighter restrictions	More liberal; protein loss in dialysate
Key complication	Access failure, catheter bacteraemia	Peritonitis, encapsulating peritoneal sclerosis, hernia

No survival difference overall. PD advantage early, HD later - technique failure limits PD to ~5-8 years

Peritoneal scarring/adhesions - multiple abdominal operations, prior gallbladder or bowel perforation, adhesive small bowel obstruction
Active intra-abdominal inflammation or malignancy
Abdominal wall hernia (repair first), surgical ostomy (exit-site infection risk)
Ventriculo-peritoneal shunt
Significant physical, cognitive or psychological impairment without a carer; unsuitable home environment
Severe respiratory disease (splinting from dwell volume), morbid obesity
Failure of ultrafiltration in high transporters

Exhausted vascular access; severe cardiac failure intolerant of ultrafiltration; unmanageable coagulopathy

Pregnancy on dialysis - intensify to up to 6 days/week to keep pre-dialysis urea below ~20 mmol/L
- More dialysis = higher live birth rate and gestational age; monitor for hypotension and polyhydramnios
Haemodynamic instability -> CRRT rather than intermittent HD; slower solute and fluid removal is better tolerated
Severe hyperkalaemia -> intermittent HD, which corrects faster than CRRT
First-ever dialysis in severe uraemia -> short, low-efficiency session to avoid disequilibrium syndrome

Education and modality choice >=6-12 months before need
Vein preservation (no cannulas, PICCs or venepuncture in the non-dominant forearm)
AV fistula ~6 months ahead; PD catheter ~2-4 weeks ahead
Pre-emptive transplant workup at eGFR 15-20 - pre-emptive transplantation gives the best outcomes
Hepatitis B vaccination (double dose, 4 doses), influenza, pneumococcal, COVID

A legitimate, actively managed pathway: symptom control, anaemia and volume management, advance care planning
Survival benefit of dialysis is small and may be absent in patients over 75 with high comorbidity or dementia, and hospital-free days may be fewer on dialysis

Late nephrology referral -> catheter start, worse outcomes
Cardiovascular disease - limits ultrafiltration tolerance and drives mortality
Diabetes - gastroparesis, vascular access difficulty, hypoglycaemia
Frailty, dementia, malnutrition - shift the balance toward conservative care
Prior abdominal surgery, hernia, obesity - PD limitations
Peripheral vascular disease, prior central lines - HD access limitations
Social circumstances - housing, remoteness, carer support (a dominant issue for Aboriginal and Torres Strait Islander patients requiring relocation from remote communities)

Once started, dialysis is usually lifelong unless transplanted - AKI-related dialysis is the exception; ~40-60% recover independent function
Median survival from dialysis start: ~5 years overall; ~2-3 years if aged >75
Transplantation approximately doubles life expectancy in eligible patients
Technique failure on PD ~10-15%/yr - peritonitis, ultrafiltration failure, catheter problems -> transfer to HD
Withdrawal from dialysis accounts for ~10-15% of deaths - revisit goals of care regularly
Preserving residual renal function improves survival on both modalities and permits an incremental start (e.g. twice-weekly HD)

12 more sections, plus exam facts

Premium unlocks every note across every specialty, and the full exam fact library behind it.