Case 1 - AKI Flashcards
How is AKI staged?
Creatinine levels OR urine output
Acute tubular necrosis vs pre-renal cause of uraemia
Risk of fatality of AKI
Similar to that of MI
What does creatinine levels depend on?
Production - eg if large muscle mass breakdown levels will be higher
Poor kidney function - not clearing
Why do we use creatinine for AKI?
- More sensitive marker of disease than eGFR
- Produced and excreted at constant rate ish
Stage 1 AKI
- 1.5-1.9 baseline creatinine
- OR 0.3mg/dl or more (26.5 umol/l or more)
OR <0.5ml/kg for 6-12hrs urine output
Stage 2 AKI
- 2-2.9 x baseline
- OR <0.5mls/kg for 12 hrs or more
Stage 3 AKI
- 3x baseline
- OR 4mg/dl or more (353.6umol/L or more)
OR
* <0.3mls/kg for 24hrs or more
* or anuria for 12 hrs
OR
* Renal replacement therapy commenced
3 types of causes of an AKI
- Pre renal
- Renal
- Post renal
Risk factors for AKI
- Diabetes
- CKD
- IHD/CHF/CVD
- Major medical co-morbiditiy (any)
- Elderly >75
- Sepsis
- Medications - ACEi, ARBs, NSAIDs, Abx
Pre-renal causes of AKI
- Hypovolaemia
- Decreased CO
- CHF
- Liver failure
- Impaired renal autoregulation
- NSAIDs
- ACEi/ARBs
- Cyclosporine
Intrinsic renal causes of AKI categories
- Glomerular
- Tubules and intersitium
- Vascular
Vascular causes of intrinsic AKI
- Vasculitis
- Malignant hypertension
- TTP-HUS (thrombotic thrombocytopenia purpura-haemolytic uraemic syndrome)
Tubules and intersitium causes of intrinsic AKI
- Ischaemia
- Sepsis/infection
- Nephrotoxins
Examples of exogenous nephrotoxins
- Iodinated contrast
- Aminoglycosides eg gentamicin
- Cisplatin
- Amphotericin B
Examples of endogenous nephrotoxins which cause intrinsic AKI
- Haemolysis
- Rhabdomyolysis
- Myeloma
- Intratubular crystals
Post renal causes of AKI
- Bladder outlet obstruction
- Bilateral pelvoureteral obstruction (or unilateral if only 1 kidney functioning)
Investigations for AKI - bedside
- Urine dipstick - protein and blood
*
Bloods for suspected AKI
- FBC
- U&Es
- LFTs
- Bone profile
- CRP
- Include serum bicarbonate
- CK if suspect Rhabdo
What test to do if blood and protein on urine dipstick?
- c-ANCA (PR3) and p-ANCA (MPO) - to look for vasculitis
- Anti GBM, ANA, C3 and C4 - for lupus nephritis
- Serum immunoglobulins and electrophoresis - to look for myeloma
Test if suspect post streptococcal glomerulonephritis
- Anti-streptolysin O titres
What to consider if AKI with thrombocytopaenia?
- HUS
- TTP
- DIC
Therefore request haemolysis screen
Bloods in haemolysis screen
- Blood film
- LDH
- Bilirubin
- Reticulocytes
- Haptoglobin
and call Renal SpR urgently
When to check cryoglobulins?
- Unexplained rash
- Peripheral neuropathy
- Hypocomplementaemia
- Hepatitis C known
- History of lymphoproliferative disorder
- Positive Rh F
Management of AKI
- Discontinue nephrotoxic agents
- Ensure volume status and perfusion pressure - IV fluids if dehydrated, diuretics if overloaded –> euvolaemia
- Third spaced fluids? - overloaded appearance but JVP and BP low
- CVP/arterial line for haemodynamic monitoring?
- Monitor urine output and daily bloods (catheterise if needed)
- Avoid hyperglycaemia
- Check for changes needed in drug dosing
- Treat cause
- Refer specialist if needing renal replacement therapy
- Consider ICU admission
Indications for RRT
- Hyperkalaemia - resistant to medical therapy
- Metabolic acidosis - reistant to medical therapy
- Fluid overload - resistant to diuretics
- Uraemic pericarditis
- Uraemic encephalopathy - vomit, confused, drowsiness, reduced conc
- Intoxications - ethylene glycol, methanol, salicyclates, lithium
Fluid assessment involves…
- Capillary refill
- Skin turgour
- Pulse and RR
- BP
- JVP
- Mouth dry?
- Auscultate lungs and heart
- Abdo - percuss, assess shifting dullness
- Sacral and leg oedema
- Weight check
- Urine output monitoring
Drugs to stop in AKI
- Diuretics
- Aminoglycosides and ACEi
- Metformin
- NSAIDs (except aspirin at cardioprotective dose)
DAMN
Also remember lithium toxicity risk increases, consider stopping
