AKI Flashcards
Define an AKI
Acute kidney injury is an acute- occurring over hours to days- drop in kidney function
There are many different AKI criterias; describe the NICE criteria for an AKI
- Rise in creatnine of >/=26umol/L in 48hr
- Rise in creatinine of >/=50% in 7 days
- Urine output of <0.5ml/kg/hour for >6hrs
There are many different AKI criterias; describe the KDIGO criteria
*Idea that this uses ____ x baseline
State some risk factors for developing an AKI
*HINT: think about conditions, drugs etc…
- CKD
- Previous AKI
- Heart failure
- Diabetes
- Liver disease
- Older age (>65yrs)
- Cognitive impairment
- Nephrotoxic medications e.g. NSAIDs, ACEinhibitors, ARBs, diuretics, aminoglycosides
- Use of contrast medium e.g. in CT scans
- Neurological/cognitive impairment leading to decreased fluid intake
State some causes of AKI
*Make sure you classify causes into 3 main categories and explain what is meant by each category
Pre-renal: inadequate blood supply to kidneys resulting in reduced filtration rate:
- Dehydration
- Hypotension (e.g. shock)
- Heart failure
- Renal artery stenosis
Renal: intrinsic renal disease/damage to glomeruli, renal tubules or interstitium resulting in reduced filtration rate:
- Glomerulonephritis
- Interstitial nephritis
- Acute tubular necrosis
- Tumour lysis syndrome
- Rhabdomyolysis
Post-renal: obstructon to outflow of urine causing back pressure into kidney and reduced renal function- known as obstructive uropathy:
- Kidney stones
- Masses causing external compression of ureters e.g. cancers in abdo, pelvis
- Ureter or urethral strictures
- Enlarged prostrate (e.g. BPH or cancer)
What are the symptoms & signs of an AKI- consider what each symptom might suggest about caue of AKI
- Dizziness (suggesting pre-renal AKI)
- Thirst (suggesting pre-renal AKI)
- Reduced urine output
- Lower urinary tract symptoms e.g. hesitancy, urgency, frequency (suggestive of obstructive uropathy)
- Loin pain
- Hypotension
- Pulmonary or peripheral oedema
- Features of uraemia (pericarditis, encephalopathy)
- Arrhythmias due to electrolyte imbalances
What investigations would you do if you suspect AKI, include:
- Bedside
- Bloods
- Imaging
NOTE: this list isn’t exhautive, other potential investigations will be discussed on alternative flashcard
Bedside
- Urine dip stick: look for infection and/or inflammation
- Urinalysis: urine culture to check for infection
- BMs: check for diabetes
- Monitor urine output
- ECG: hyperkalaemia is common complication
- VBG/ABG: check for acidosis, check lactate if ?sepsis
Bloods
- FBC: WCC
- U&E: urea, creatinine, electrolytes
- LFTs: ?hepatorenal syndrome
- CRP:infection
- Blood culture:?sepsis
- Coagulation: ?conditions with AKI and abnormal clotting e.g. HUS, thrombotic thrombocytopenic purpura
- CK: ?rhabdomyolysis
Imaging
- Ultrasound KUB: look for obstruction
- CXR: to rule out infections e.g. pneuomonia, cardiomegaly of HF
What does leucocytes & nitrates suggest on urine dipstick?
What does protein & blood suggest on urine dipstick?
- Leucocytes & nitrates suggest infection
- Protein & blood suggest acute nephritis (but could also be infection)
If there is blood & protein on urine dipstick, in pt with suspected AKI, what further investigations would you request?
Suggests acute nephritis so look for antibodies:
- c-ANCA & p-ANCA:: vascultitis
- anti-GBM: Goodpasture’s/anti-GBM disease
- ANA, C3 & C4:b lupus nephritis
- Serum immunoglobulins & electrophoresis: myeloma
If you suspect post-streptococcal GN as cause of AKI, what further investigation would you do?
Anti-streptolysin O Titres
*NOTE: post streptococcal glomerulonephritis often develops about 10-14 days after skin or throat infeciton with group A beta haemolytic Streptococci. It is immune systems response that causes glomerulonephritis- not the bacteria itself
If a pt has an AKI and also has thromboyctopenia what conditions would you consider as cause?
What further investigations would you request?
Consider:
- Haemolytic uraemic syndrome
- Thrombotic thrombocytopenic purpura
- Disseminated intravascular coagulopathy
You would need to request haemolysis screen (includes blood film, LDH, bilirubin, reticulocytes, haptoglobin) and call renal SpR urgently
What is haptoglobin?
What is it used to assess?
Intepret low, normal & high results
- Protein that binds to free Hb, that has been released by destroyed RBCs, and transports the haemoglobin back to liver where it can be broken down and products re-used or excreted
- Used to assess haemolytic anaemia
- Results need to be interpretted alongside Hb and reticulocytes
When would you consider checking cyroglobulins in a pt with supsected AKI?
- Unexplained rash
- Peripheral neuropathy
- Hypocomplementaemia
- Known hepatitis C
- +ve RhF
- History of lymphoproliferative disease
What blood tests must you do daily for someone with an AKI?
- FBC
- U&E
- LFTs
- Bone profile
- CRP
- Serum bicarb
- CK (if rhabodmyolysis suspected)
*UHL policy states do U&Es, bone, venous bicarb daily
Ultrasound of kidneys is only necessary if you think the cause of AKI is obstructive; true or false?
True
Discuss how you should approach the management of an AKI
*HINT: not asking for specific management just asking for a general approach
1.) Is there a life threatening cause or complication that needs treating urgently?
- Sepsis?
- Pulmonary oedema? (needs early referral to renal as may need dialysis)
- Hyperkalaemia
2.) Try to identify underlying cause and treat it
3.) Stop nephrotoxic medications if possible & consider renal doses of any necessary medications
4.) Refer to specialist for consideration of renal replacemen therapy
5.) Consider ICU
Discuss the management of a:
- Pre-renal
- Renal
- Post-renal
… AKI
Aspects of management common to all includes fluid balance, management of acidosis and hyperkalaemia.
Pre-renal
- IV fluids
- Try to manage condition that is causing decreased perfusion to kidneys e.g. manage heart failure, manage D&V,
Renal
- Treat underlying cause e.g. immunosupressants for glomerulonephritis
Post-renal
- Relieve obstruction
- Catheterise
What medications should be stopped in AKI?
Ensuring adequete fluid status in a pt with AKI can be difficult; discuss the difficulties of managing fluids in AKI
- Pt may look overloaded but may have intravascular depletion (due to third space losses); assess JVP and BP to guide you
- If overloaded need diuretics but don’t want to compromise BP
- If need diuretics, often need large dose due to decreased GFR; large doses of diuretics can be nephrotoxic
Idea that it is a fine balancing act
State the 4 main complications of an AKI and for each explain how they arise
- Hyperkalaemia: decreased filtration, decreased renal excretion
- Fluid overload which may manifest as heart failure and pulmonary oedema: decreased filtration, decreased losses
- Metabolic acidosis: decreased removal of acids from blood, bicarb used up
- Uraemia: decreased urea excretion
State 2 potential consequences of uraemia
- Encephalopathy
- Pericarditis
State some indications for renal replacement therapy
- Hyperkalaemia refractory to medical therapy
- Metabolic acidosis refractory to medical therapy
- Fluid overload refractory to diuretics (anuric)
- Uraemic pericarditis
- Uraemic encephalopathy
- Intoxications
State some situations in which you would seek advice/review from renal team
- AKI not responding
- AKI with complications: hyperkalaemia, fluid overload, acidosis
- AKI with difficult fluid balance e.g. HF, pregnancy
- AKI with possible intrinsic renal disease
- AKI with hypertension
What are the most common causes of AKI
Pre-renal= most common
e.g. Sepsis, cardiogenic shock, other hypovolaemia, hepatorenal syndrome
