Acute and Chronic renal Failure 1 Flashcards
What is an AKI?
A potentially reversible abrupt decline in GFR with treatment targeted at diagnosis and reversal of disease.
What is CKD?
An irreversible longstanding decline in GFR with treatment aimed at prevention of complications and progression. (>3 months)
What is acute failure of kidneys?
A rapid reduction in kidney function, leading to an inability to maintain electrolyte, acid-base and fluid homeostasis.
Is an AKI an emergency?
Yes- immediate referral for management in nephrology
What are the stages of an AKI?
AKI Stage 1: Increase in sCr by ≥26 µmol/L, or by 1.5 to 1.9x the reference sCr
AKI Stage 2: Increase in sCr by 2.0 to 2.9x the reference sCr
AKI Stage 3: Increase in sCr by ≥3x the reference sCr, or increase by ≥354 µmol/L
What are the types of AKI?
Pre renal
Renal
Post Renal
What is a pre renal AKI?
Reduced tissue perfusion/ local ischaemia
NO structural abnormality
What is a normal response to reduced circulating volume?
Activation of central baroceptors activates RAS and there is a release of vasopressin and sympathetic system which causes vasoconstriction, increased cardiac output and renal sodium retention.
What are the causes of pre renal AKI?
True volume depletion Hypotension Oedematous states Selective renal ischaemia Drugs affecting glomerular blood flow
Renal artery stenosis
Which class of drugs may commonly predispose patients to developing pre-renal AKI?
ACEi
How do these drugs cuase pre renal AKI: NSAIDS ACEi/ARBs Calcineurin inhibitors Diuretics
NSAIDs - decrease afferent arteriolar dilatation
Calcineurin inhibitors - decrease afferent arteriolar dilatation
ACEi or ARBs - decrease efferent arteriolar constriction
Diuretics – affect tubular function, decrease preload
How can AKI lead to ATN?
Pre-Renal AKI is not associated with structural renal damage and responds immediately to restoration of circulating volume
Prolonged insult leads to ischaemic injury
Acute Tubular Necrosis does not respond to restoration of circulating volume
What is the hallmark of post renal AKI?
Physical obstruction to urine flow.
What may cause post renal AKI?
(Intra-renal obstruction) Ureteric obstruction (bilateral) Prostatic / Urethral obstruction Blocked urinary catheter
What is the pathophysiology of obstructive uropathy?
GFR is dependent on hydraulic pressure gradient
Obstruction results in increased tubular pressure
Immediate decline in GFR
How do you recover from obstructive uropathy?
Immediate relief of obstruction restores GFR fully, with no structural damage
What can prolonged obstruction cause?
Glomerular ischaemia
Tubular damage
Long term interstitial scarring
What is are the types of intrinsic AKI?
Vascular Disease e.g. vasculitis
Glomerular Disease e.g. glomerulonephritis
Tubular Disease e.g. ATN
Interstitial Disease e.g. analgesic nephropathy
How does direct tubular injury occur?
Ischaemia Endogenous toxins (Myoglobin, Igs) Exogenous toxins (Aminoglycosides, amphotericin, acyclovir)
Patient has new onset AKI, haematuria and massive bruising. What is the likely diagnosis?
Rhabdomyolysis (Myoglobin is toxic)