Flashcards in AKI and CKD Deck (65):
What variables are used to estimate eGFR from serum creatinine?
What is uremia?
Excessive urea (and other amino acid and protein metabolism end products) in that blood.
These would normally be excreted in the urine.
What test can be done to differentiate pre-renal uraemia and acute tubular necrosis?
Pre-renal uraemia: <20 mmol/L
ATN: >30 mmol/L
How does Stage 1 AKI present?
Serum creatinine increase of 1.5-1.9x baseline
Urine output of <0.5ml/kg/hr for >6h
How does Stage 2 AKI present?
Serum creatinine increase of 2.0-2.9x baseline.
Urine output of <0.5ml/kg/h for >12h
How does Stage 3 AKI present?
Serum creatinine increase of >3x baseline
Urine output of <0.3ml/kg/h for >24h, or anuric for 12h
What is the name of the syndrome presenting with: acute renal failure, microangiopathic haemolytic anaemia, and thrombocytopenia?
Haemolytic uraemic syndrome
List 4 causes of haemolytic uraemic syndrome
Post-dysentery - E. coli
Ciclosporin and COCP
What nephrotic syndrome typically occurs in children and young adults?
Minimal change glomerulonephritis
What is the definition of contrast media nephrotoxicity?
25% increase in creatinine occurring within 3 days of IV administration of contrast media.
What are the risk factors for contrast media nephrotoxicity?
Known renal impairment - especially diabetic nephropathy
What is the best preventative measure of contrast media nephrotoxicity?
IV 0.9% saline for 12h pre- and post-procedure
When is a reduced eGFR not diagnosed as CKD?
If eGFR is >90, or 60-90, but the renal tests are normal (normal U&E with no proteinuria)
What is Stage 1 CKD?
eGFR >90 ml/min, with some sign of kidney damage on other tests
What is Stage 2 CKD?
eGFR 60-90 ml/min with some sign of kidney damage
What is Stage 3a CKD?
eGFR 45-59 ml/min
What is Stage 3b CKD?
eGFR 30-44 ml/min
What is Stage 4 CKD?
eGFR 15-29 ml/min
What is Stage 5 CKD?
eGFR <15 ml/min
What is the purpose of EPO injections in CKD?
Treatment for CKD-associated anaemia. Improves exercise tolerance.
What adult polycystic kidney screening test is recommended for family members?
Name 3 classifications of AKI
Define Acute kidney injury (AKI)
Abrupt deterioration in renal function, over hours-days.
Usually reversible over days-weeks.
Describe the broad aetiology of AKI
List 3 causes of pre-renal AKI
Hypovolaemia: haemorrhag, severe DaV, burns, diuresis
Hypotension: shock, sepsis, anaphylaxis
Hypoperfusion: HF, cirrhosis, AAA, renal artery stenosis, NSAIDs, COX-2 inhibitors
How do NSAIDs and COX-2 inhibitors cause pre-renal AKI?
Inhibits COX enzymes which are needed for prostaglandin synthesis, a vasodilator.
List 4 causes of intrinsic renal AKI
Glomerular disease: glomerulonephritis, thrombosis, SLE, haemolytic uraemic syndrome
Tubular injury: ATN, nephrotoxins
Vascular: Vasculitis, renal artery stenosis, thrombosis
List 4 causes of post-renal AKI
Ureteric: Bilateral renal stones, retroperitoneal fibrosis, tumours
Bladder: Acute urinary retention, blocked catheter
Urethral: Prostate enlargement, renal stones
What are 4 risk factors for AKI?
Chronic disease: CKD, HF, PVD, Chronic liver disease, DM.
Poor fluid intake/XS losses
Hx of urinary symptoms
What symptoms can occur in AKI?
Oliguria or anuria
What signs can occur in AKI?
Enlarged bladder if chronic urinary retention
Dehydration with postural hypotension
Fluid overload, raised JVP, peripheral and pulmonary oedema
What steps can be taken to prevent AKI?
Regular monitoring of renal function in chronic diseases.
Close monitoring in acute illness, especially if dehydration or DaV is present.
Optimise doses of drugs with nephrotoxic potential.
Consider stopping ACEi and ARBs if DaV or sepsis occurs.
Consider admitting to hospital if hypovolaemic, for IV fluids.
What electrolyte disturbances occur in AKI?
What is the goal of initial investigations in suspected AKI?
To define the syndrome as pre-renal, intrinsic, or post-renal.
Decide if it is acute or acute-on-chronic kidney disease.
What initial investigations should be undertaken for suspected AKI?
-Volume status: BP, JVP, skin turgor, cap refill, urine output (catheter)
-Serum K+ (VBG)
-ECG for hyperkalaemia
-Urine dipstick/blood film for glomerulonephritis
-KUB USS for urinary tract obstruction
What ECG changes occur in hyperkalaemia?
Tall tented T waves
Small/absent p waves
Increased PR interval
Sine wave pattern
What is the immediate treatment of life-threatening hyperkalaemia?
10ml of 10% calcium gluconate IV via big vein. (cardioprotective)
IV insulin + glucose
Definitive Tx: renal clearance or haemodialysis
What blood tests should be done in suspected AKI?
FBC and blood films for glomerulonephritis
U&Es, creatinine, CRP
Coagulation for DIC associated with sepsis
CK for rhabdomyolysis
Bence Jones' protein for myeloma
ANA and anti-dsDNA for SLE
ANCA for vasculitis and GPA
What features suggest acute-on-chronic kidney disease rather than AKI?
Long Hx of nocturia
KUB USS: small, scarred kidneys
Anaemia of chronic disease
Outline the management of AKI
-Fluid and electrolyte monitoring BD. Aim for euvolaemia.
-Stop nephrotoxic drugs and adjust renal excreted drugs.
-Maintain nutrition. Restrict K+ and Na+.
Pre-renal: correct fluid depletion, treat sepsis, refer to ICU if enter shock.
Post-renal: catheterise and consider CTKUB. Discuss with urology if signs of obstruction or hydronephrosis.
What are the indications for Renal Replacement Therapy (RRT)?
Refractory pulmonary oedema
Persistent hyperkalaemia (>7mmol/L)
Severe metabolic acidosis (pH <7.2)
Drug OD (BLAST*)
*Barbituates, Lithium, Alcohol, Salicylates, Theophyline
Name 4 complications of AKI
What are the consequences of uraemia?
Outline the treatment of pulmonary oedema
Sit up and give high-flow O2
Venous vasodilator (Diamorphine + antiemetic)
If no response: urgent haemodialysis or filtration
Name the types of Renal Replacement Therapy (RRT)
Which types of RRT are suitable for AKI?
Describe the process of haemodialysis
Blood and dialysis fluid flow in opposite directions on different sides of a semi-permeable membrane.
Water and solutes diffuse across this membrane into the dialysis fluid, across a -ve transmembrane pressure.
This allows removal of several litres of excess fluid over 3-5 hours.
What routes of administration are used in haemodialysis?
IV catheter (central vein): If urgent dialysis needed. Slower rate, infection and stenosis risk.
AV fistula: Lowest risk of infection, takes weeks to be ready. Risk of aneurysm.
AV graft: Increased risk of infection. Used if poor veins or arterial disease.
Compare haemodialysis and haemofiltration
Haemodialysis removes solutes by diffusion. Given for short periods. Better solute clearance, but requires patients to be haemodynamically stable.
Haemofiltration removes soluted by convection (water pressure). Given continuously, typically on ICU. Provides better control of blood pressure.
What are the problems with haemodialysis?
Dialysis disequilibrium syndrome
Time consuming, inflexible, dietary restrictions
Fistula: thrombosis, stenosis, aneurysm, steal syndrome, ischaemia
Temporary line: infection, blockage
What are the benefits of haemodialysis?
Fast clearance rate
Short periods of treatment with return to normal lifestyle in between treatments.
What is dialysis disequilibrium syndrome?
A rare syndrome of neurological symptoms due to cerebral oedema occurring after haemodialysis.
More commonly seen in first dialysis sessions, elderly and paediatric patients, pre-existing CNS lesions, and severe metabolic acidosis.
Tends to be self-limiting. Dialysis will need to stop if severe.
What is steal syndrome?
Arterial stenosis upstream of an anastomosis (fistula/graft), which prevents the necessary increase in flow. This causes distal peripheral ischaemia.
How often is haemodialysis required on a weekly basis?
3 sessions a week of 4-5hr duration.
Describe the process of peritoneal dialysis
Dialysate is inserted into the peritoneal cavity via a catheter. Waste products cross into the cavity. This is left in the abdomen for 3-5 hours before being exchanged and repeated.
What are the benefits of peritoneal dialysis?
Patient freedom and control.
Less fluid and food restrictions.
What are the problems with peritoneal dialysis?
Patients are responsible for continuous care, and need 3-5 exchanges a day.
Sclerosing peritonitis (causes potentially fatal repeated small bowel obstruction)
Catheter exit-site infections
Obesity, due to glucose in dialysate
Hernias and back pain
How common are renal cysts?
Common, especially with advancing age.
50% of over 50yrs have one or more renal cysts
What is the clinical significance of renal cysts?
No special significance except in the differential diagnosis of renal tumours.
Often an asymptomatic incidental finding. May cause pain and/or haematuria if large.
What is renal cystic degeneration? Explain its clinical significance
The formation of multiple cysts that enlarge with time.
Cystic degeneration occurs regularly in non-functioning kidneys of patients with ESRD treated by dialysis and/or transplantation.
These acquired cysts have malignant potential.
Define Autosomal dominant polycystic kidney disease
Inherited disorder that is characterised by the development of multiple renal cysts, and associated with extrarenal (mainly hepatic and CV) abnormalities.
Outline the epidemiology of Autosomal dominant polycystic kidney disease
Most common inherited nephropathy
3-10% of all patients commencing regular dialysis
Describe the clinical presentation of Autosomal dominant polycystic kidney disease
Occur from second decade onwards
Loin pain and/or haematuria
Loin or abdominal discomfort
Subarachnoid haemorrhage: berry aneurysm rupture
Complications of HTN
Complications of associated liver cysts (50%)
CKD associated uraemia and/or anaemia
Name 3 conditions associated with Autosomal dominant polycystic kidney disease
Progressive CKD*: faster deterioration than other primary renal disorders
Renal calculi (10-20%): often urate and radiolucent
Hypertension: early and common feature
Left ventricular hypertrophy
Mitral valve prolapse
Berry aneurysm -> Subarachnoid haemorrhage