Acute Kidney Injury Flashcards
what is an acute kidney injury
an abrupt (<48 hrs) reduction in kidney function:
- absolute increase in serum creatinine levels by >26
- increase in creatinine by >50%
- reduction in UO
what is stage 1 AKI
increase > 1.5-1.9 x creatinine reference
<0.5ml/kg/hr urine output for >6 hours
what is stage 2 AKI
increase >2-2.9 x reference creatinine
<0.5ml/kg/hr urine output for >12 hours
what is stage 3 AKI
increase >3 x reference creatinine
or increase to >354
or need for RRT
<0.3ml/kg/hr urine output for >24 hours or no urine output for 12 hours
what are some risk factors for AKI
older age chronic kidney disease diabetes cardiac failure liver disease peripheral vascular disease previous AKI
what are the 3 categories of AKI causes
Pre-renal (eg. change on blood volume to kidneys) Renal (structural) Post renal (obstruction)
what is the most common cause of AKI
Pre-renal
what are some pre-renal causes of AKI
Hypovolaemia
- haemorrhage
- volume depletion (burns)
Hypotension
- cardiogenic shock (heart failure)
- distributive shock (sepsis)
Renal hypoperfusion
- NSAIDS
- ACEi/ARBs
- hepatorenal syndrome
what does an untreated prerenal AKI lead to
Acute tubular necrosis
What is a pre-renal AKI
reversible volume depletion leading to oliguria and increased serum creatinine
what are the most common conditions to cause pre-renal AKI
sepsis
severe dehydration
rhabdomyolysis
drug toxicity
treatment for pre-renal AKI
asses hydration
- NEWS
- JVP, capillary refit time, oedema
Fluid challenge for hypovolaemia
-normal saline (0.9% NaCl) bolus then reassessment and repeat if necessary
what is a renal AKI
disease causing inflammation or damage to cells causing an AKI
what are the main types of disease that cause renal AKI
Blood vessel disease
Glomerular disease
Interstitial injury
Tubular injury
what diseases affect the renal blood vessels causing AKI
vasculitis renovascular disease (atherosclerosis in vessels in kidneys)
what glomerular diseases cause renal AKI
glomerulonephritis
what interstitial injuries cause renal AKI
Drugs - penicillin, NSAIS, PPIs
Infection - TB
Systemic disease (sarcoidosis)
what tubular injuries cause renal AKI
ischaemia (prolonged renal hyper perfusion)
drugs (gentamicin)
contrast
rhabdomyolisis
what are the sings/symptoms of renal AKI
anorexia weight loss fatigue lethargy nausea and vomiting itch, pericarditis (uraemic symptoms) fluid overload (oedema, SOB) oliguria
what clues in the history suggest a renal AKI
rash (lupus or vasculitis) sore throat joint pain (lupus) haemoptysis drug history recent contrast scans blood results (suggestive of vasculitis)
what type of AKI is it if there is protein and blood in the urine
renal cause of AKI
how long after a contrast scan does contrast nephropathy occur
within 72 hours
what does eosinophilia suggest
eosinophilic granulomatosis with polyangitis
what should you be worried about if patient has come in after lying for a v long time
rhabdomyolysis
what investigations are done for renal AKI
Us&Es FBC and coagulation screen Urinalysis USS Immunology Protein electrophoresis
treatment for general AKI
establish good perfusion pressure (fluid resuscitate and then vasopressors if needed)
treat underlying causes (antibiotics if sepsis)
stop nephrotoxins
dialysis if patient remains anuric and uraemia
what are some life threatening complications of AKI
hyperkalaemia
fluid overload
severe acidosis
ureic pericardial effusion
severe uraemia
what is a post renal AKI
AKI due to obstruction of urine flow leading to back pressure (hydronephrosis) and therefore loss of concentrating ability of the kidneys
what are some causes of post renal AKI
stone
cancers
strictures
extrinsic pressure
what is the treatment for post renal AKI
relieve obstruction
- catheter
- nephrostomy
refer to urology if ureteric stenting required
what is hyperkalaemia
life threatening condition of too much K in the blood
associated with cardiac arrhythmia
what are the ranges for normal - life threatening hyperkalaemia
normal - 3.5-5
hyperkalaemia >5.5
life threatening hyperkalaemia >6.5
how do you treat hyperkalaemia
- Cardiac monitor and IV access
- Protect myocardium (calcium gluconate)
- Move K+ back into cells (insulin with 50ml dextrose, salbutamol nebs)
- Prevent absorption from GI tract (calcium resonium)
what gives urgent indication for dialysis
hyperkalaemia >7 or >6.6 but unresponsive to medical therapy
severe acidosis - pH 7.15<
fluid overload
real pericardial rub/effusion
what is the mortality rate for AKI alone
10-30%
what is the mortality rate for AKI with one other organ dysfunction
30-50%
what is the mortality rate for AKI with multi-organ failure
70-90%
what percentage of people recover from AKI but have progressive CKD
5-10%
Triggers for AKI
hypotension hypovolaemia sepsis deteriorating NEWS recent contrast scan exposure to certain drugs
