Acute Kidney Injury Flashcards
Definition
Abrupt decrease in kidney function- rise in serum creatinine by 26.4 micro mols or 50%
Fall in urine output <0.5ml/kg/hour >6 hours
Most common cause of AKI
Acute tubular necrosis
Pre- renal causes
Hypovolaemia- burns, D+V, Haemorrhage
Hypotension- cardiogenic shock, sepsis, anaphylaxis
Hypoperfusion- NSAIDS, COX inhibitors, hepatorenal syndrome
Renal causes
Vascular- thrombosis, embolism, vasculitis, polyarteritis nodosa
Glomerular- acute GN, acute vasculitis, SLE, HSP, good pastures
Interstitial nephritis - drug induced (NSAID, Cephalosporins), TB, Sarcoidosis, lymphoma
Tubular injury- contrast, rhabdomyolysis, hypercalcaemia
Post renal causes
Stones
Cancer
Strictures
External compression
Pathophysiology of pre-renal AKI
Volume depletion leads to decreased effective intravascular volume
Increased ADH + aldosterone leads to salt and water retention –> oliguria + AKI
Pathophysiology of renal AKI
inflammation/damage to cells
Pathophysiology of post-renal AKI
Obstruction of urine flow leading to hydronephrosis + loss of contracting ability
Symptoms of AKI
Decreased urine output Fluid retention - oedema Anorexia, weight loss, fatigue vomiting SOB, palpitations
Signs of AKI
Hypertension Pulmonary oedema Plural effusions Uraemia- itch, pericarditis Oliguria
Investigations
U+Es FBC + Coagulation screen Urinalysis USS KUB Immunology Biopsy
When is a biopsy indicated
suspected rapidly progressing GN
+ve immunology + AKI
Stage 1 classification of AKI
Creatinine >26.4 or increase by 150-200%
Stage 2 classification of AKI
Creatinine increase by 200-300%
Stage 3 classification of AKI
Creatinine increase by 300% or >350micromols or need for renal replacement therapy
When is haemodialysis indicated
Hyperkalaemia Severe acidosis Fluidoverload Pericardial effusion Urea >40
Appearance of acute tubular necrosis in the urine
Muddy brown casts
what is the urine sodium like in a pre-renal AKI
Low urine sodium
- kidney is trying to concentrate urine and retain sodium
what is the urine sodium like in a renal AKI e.g. acute tubular necrosis
High urine sodium
- kidney can no longer concentrate urine and retain sodium
what drugs can cause acute interstitial nephritis
penicillin
NSAIDS
rifampicin
what is seen with acute interstitial nephritis
eosinophilia
AKI causes what blood gas result
metabolic acidosis
what antibiotic can cause acute tubular necrosis
gentamicin
