AKI Flashcards
Define AKI?
Rapid reduction in kidney function
Over hours - days
As measured by serum, urea and creatinine
Leading to a failure to maintain fluid, electrolyte and acid-base homeostasis
What is the KDIGO criteria of AKI?
Rise in serum creatinine of 26+ micromol/L in 48 hours
A 50% or greater rise in serum creatinine in preceding 7 days
UO < 0.5ml/kg/hr for 6 hours (or 8 in children)
What 3 components are used to stage AKI?
Creatinine
GFR
Urine output
Describe AKI staging?
RIFLE
Stage 1, 2, 3
- risk
- raised creatinine x 1.5
- <0.5ml/kg/hr UO in 6h - injury
- raised creatinine x 2
- <0.5ml/kg/hr UO in 12h - failure
- raised creatinine x 3
- <0.3ml/kg/hr UO in 24hrs OR anuria for 12h
What is creatinine?
Breakdown product of creatine kinase or creatine phosphate which is in muscles
3 categories of causes of AKI?
Pre-renal
Intrinsic renal
Post-renal
What are the pre-renal causes of AKI?
Hypotension: volume depletion (haemorrhage, severe D+V, burns) sepsis, cardiogenic shock
Oedema: cardiac failure, cirrhosis, nephrotic syndrome
Renal hypoperfusion: drugs, AAA, renal artery stenosis/occlusion
Which drugs can cause AKI? And how?
ACE inhibitors
ARBs
NSAIDs
COX2 inhibitors
Diuretics
Gentamicin
Contrast for CT scans
What are the intrinsic renal causes of AKI?
Glomerular disease
- glomerulonephritis
- thrombosis
- haemolytic uraemic syndrome
Tubular injury
- acute tubular necrosis after ischaemia
- nephrotoxins
Acute interstitial nephritis
- drugs (NSAIDs)
- infection
- autoimmune
Vascular:
- vasculitis
- renal artery stenosis
- renal vein thrombosis
Eclampsia
Multiple myeloma
What are the post-renal causes of AKI?
SNIPPIN
Stone Neoplasm Inflammation Prostate Posterior urethral valves Infection Neuropathic bladder
Risk factors for AKI?
Age over 65
CKD
History of AKI
Co-morbidities
Reliance on carer for access to fluids (eldery, children, disabled)
Sepsis
Urological obstruction
Drugs: ACEi, ARBs, NSAIDs, diuretics
Peri-operative period
Investigations of suspected AKI?
Assess volume status
Urgent K+
ECG
Urinalysis + MC+S
- Bence jones protein
Blood tests: FBC, U+E, LFTs, creatinine, coag, CK, CRP, ESR
Where appropriate USS, AXR, MRI
How can you assess patient’s volume status?
BP Pulse Skin turgor Mucous membranes CRT
Presentation of AKI?
Azotaemia, uraemia
Oliguria or anuria
Hyperkalaemia
Fluid overload (oedema, hyper/hypotension, raised JVP)
N+V
Dehydration
Confusion
Plus symptoms relating to the cause of the AKI
What are the symptoms of uraemia?
Nausea Vomiting Fatigue Anorexia Weight loss Muscle cramps Pruritus Confusion
Management of AKI?
Pre-renal: correct the volume depletion, treat cause
Intrinsic renal: refer nephrology
Post-renal: catheterise, treat cause
Supportive
- fluid balance (i.e don’t overload)
- stop nephrotoxic drugs
- monitor electrolytes, creatinine closely
- nutritional intake
What are the complications of AKI?
Hyperkalaemia
Acidosis
Pulmonary oedema
Bleeding
Features of hyperkalaemia on ECG?
Peaked T waves
Flattened P waves
Increased PR
Wide QRS
Sine wave pattern leading to VF
What are the signs of fluid overload?
Oedema (pulmonary, peripheral)
Raised JVP
Hyper/hypotension
S3 gallop
Why does AKI cause acidosis?
Metabolic products that are acidic aren’t being excreted
Uraemia
Why does AKI cause bleeding?
Raised urea causes impaired haemostasis
How do you manage hyperkalaemia?
Calcium gluconate
Glucose and insulin (because insulin draws glucose into cells, which takes K with it)
Salbutamol nebulisers (works same as glucose and insulin)
How do you manage pulmonary oedema?
High flow oxygen
Morphine
Furosemide
How do you manage uraemia?
Fluids
Dialysis may be required
But if not treat the symptoms
