Stages of renal dysfunction
| Stage |
Description |
Creatinine clearance
(ml/min/1.73m2) |
Metabolic consequences |
| 1 |
Normal |
>90 |
|
| 2 |
Early renal insufficiency |
60-89 |
Inc. serum PTH |
| 3 |
Chronic renal failure |
30-59 |
Inc. Ca absorption, anaemia |
| 4 |
Pre-end stage failure |
15-29 |
Inc. TGs, PO4, K+.
acidosis |
| 5 |
End stage renal failure |
<15 |
Uraemia |
- Chronic renal failure = GFR < 60 ml / min
Causes of chronic renal failure
- Chronic glomerulonephritis
- Chronic pyelonephritis
- Diabetic nephropathy
- Chronic interstitial nephritis
- Chronic obstructive uropathy
- Hypertensive nephrosclerosis
- Polycystic disease
- Amyloid
- Myeloma
Treatment of chronic renal failure
- Three basic stages in treatment
- Preserve remaining nephrons
- Conservative treatment of uraemic syndrome
- Renal dialysis and transplantation
Preserve remaining nephron function
- Control of hypertension and heart failure
- Treatment of superimposed urinary tract infection
- Correction of salt and water depletion
- Careful prescribing of drugs that are potentially nephrotoxic
- Dietary protein restriction
Conservative management of uraemic syndrome
- Reduce protein intake
- Aluminium hydroxide to reduce intestinal phosphate absorption
- Vitamin D and calcium supplements to increase serum calcium
- Allopurinol to reduce serum uric acid
- Erythropoietin to correct anaemia
Renal dialysis
Indications
- Patient aged 5-70 years without significant systemic disease or
neoplasia
- Clinical deterioration despite good conservative management
- Uraemic pericarditis
- Severe renal bone disease
- Peripheral neuropathy
- Creatinine > 1,200 mmol/l
- Glomerular filtration rate < 5 ml/min
Principals
Dialysis depends on
- Diffusion = passage of solute through membrane down concentration
gradient
- Ultrafiltration = passage of solvent through membrane due
hydrostatic or osmotic pressure
Peritoneal dialysis
- Dialysis membrane = peritoneum
- Dialysis fluid low in urea and creatinine
- Also hypertonic solution due to high glucose concentration
- Dialysis occurs as a result diffusion and Ultrafiltration
- Tenckoff catheter usually inserted below umbilicus
Picture provided by Alireza Tavassoli, Ghaem Hospital,
Mashed, Iran
- Cuffs on catheter prevent leaks and infection
- Dialysis performed on either intermittent or continuous basis
- In continuous ambulatory peritoneal dialysis fluid is changed 4
times per day
Indications
- Diabetics
- Children
- Patients with poor vascular access
- Patients unable to tolerate haemodynamic instability of
haemodialysis
- Patients in whom wait for transplantation will be short
Contraindications
- Severe intraperitoneal adhesions
- Sepsis of the anterior abdominal wall
- Inflammatory bowel disease
- Abdominal wall hernias
- Stomas
- Extensive diverticular disease
Complications
- Intraperitoneal bleeding
- Perforated viscus
- Obstruction and displacement of catheter
- Dialysate leak
- Pericatheter hernias
- Sclerosing peritoinitis
Haemodialysis
- Dialysis membrane = artificial membrane
- Pumps move blood on either side of membrane in countercurrent
directions
- Solutes move across membrane by diffusion
- Vascular access obtained by:
- Arteriovenous shunt with prosthetic graft
- Arteriovenous fistula between artery and vein
- Vascular catheters in large central veins
- AV fistulas take 4-6 weeks to mature
Indications
- Slow deterioration in renal function
- Not suitable for patients who present with acute deterioration in
renal function
Sites of vascular access
- Autologous upper limb vessels
- Radiocephalic
- Ulnobasilic
- Brachiobasilic
- Saphenous vein loop
- Autologous lower limb vessels
- Saphenofemoral
- Saphenopoliteal
- Prosthetic materials
- Expanded PTFE
- Human umbilical vein
- Bovine carotid heterograft
- Patency rates vary with type of graft
- Brachiocephalic fistula - 80% at 2 years
- Brachiobasilic fistula - 60% at 2 years
- Synthetic grafts - 50% at 2 years
Contraindications
- Obesity
- Venous stenosis / thrombosis
- Arterial disease
- Subclavian vein stenosis
- Prothrombotic disorders
Complications
- Bleeding
- Thrombosis
- Vascular steal
- Aneurysm formation
- High-output cardiac failure
- Venous hypertension
Picture provided by Po Ming Teng, Singapore General
Hospital, Singapore
Haemofiltration
- Dialysis membrane = artificial membrane
- Used in ITU mainly for acute renal failure
- Pressure difference across membrane causes ultrafiltration
- Inefficient compared to haemodialysis
Bibliography
Himmelfarb J. Ikizler T A. N Engl J Med 2010;
363: 1833-1845
Parmar M S. Chronic renal disease. Br Med J 2002;
325: 85-90. Power A, Duncan N, Goodlad C.
Advances and innovations in dialyisis in the 21st century.
Postgrad Med J 2009; 85: 102-107. |