AKI Flashcards
What is AKI and what two ways is it detected?
AKI is decreased renal function detected by an increase in creatinine or a decrease in urine output
What is the improving global outcomes (KDIGO) definition of AKI? (3 parts)
Rise in creatinine >26umol/L in 48 hours
Rise in creatinine 1.5 times baseline in 7 days
Decrease in urine output to <0.5ml/kg/h for more than 6 hours
What are the stages of AKI in creatinine rise and urine output?
Stage 1 - 1.5-1.9 x baseline creatinine, <0.5ml/kg/h for 6-12 hours
Stage 2 - 2.0-2.9 x baseline creatinine, <0.5ml/kg/h >12hours
Stage 3 - .3.0X baseline creatinine, <0.3ml/kg/h for >24hours
What are some presentations of AKI?
Some patients are asymptoatic but oligouria is commonest
Nausea, vomiting, dehydration and confusion
May have symptoms of UTI, exposure to nephrotoxic drugs or PMH of renal problems
How is fluid balance assessed in renal patients?
JVP, heart rate, blood pressure, urine output, peripheral and central oedema, capillary refill
What clinical sign can indicate obstruction?
A palapable bladder
What are the clinical signs of ureamia?
Hand flap, confusion, pericardial rub
How does glomerulonephritis typically present?
With haematuria or proteinuria
Which surgical patients are at increased risk of AKI?
Vascular or emergency surgery because of hypovolaemia
CKD patients, Diabetes or heart failure
If the patient is on nephrotoxic medication
Patients having contrast need to be carefully cosidered as this is renally cleared
What is the most common cause of AKI prerenal, renal or postrenal?
Prerenal
What are the causes of prerenal AKI?
Decreased vascular volome - Haemorrhage, D and V, burns
Decreased cardiac output - Cardiogenic shock, MI
Systemic vasodilation - sepsis, drugs
Renal vasoconstriction - NSAIDs, ACE-i, hepatorenal syndrome
What are the causes of renal AKI?
Glomerular - Glomerulonephritis, acute tubular necrosis (prolonged renal hypoperfusion causing intrinsic renal damage)
Interstitial - Drug reaction, infection, infiltration (sarcoid)
Vessels - Vasculitis, thrombocytopenic purpura
What are the post renal causes of AKI?
Within renal tract - stone, renal tract malignancy, clot, stricture
Extrinsic compression - Pelvic malignancy, prostatic hypertrophy, retroperitoneal fibrosis
What are the 4 main reasons to get renal team involved for dialysis?
Fluid overload that is not responding to treatment
Hyperkalaemia
Refractive acidosis
Ureamia
What investigations should be done for AKI?
Urine dip - look for protein/haematuria, nitrates for UTI
USS within 24 hours unless AKI cause obvious
Check liver function (hepatorenal function)
Check platelets - if low do blood flim to check for haemolysis
Investigate for intrinsic renal disease if indicated (ANA [SLE], ANCA [vasculitis], anti-GBM [goodpastures])
What does creatinine kinase in blood tests indicate?
It shows rhabdomyolysis
How does urine output vary between pre renal and intirinsic renal AKI?
Pre renal is low
Intrinsic renal is initially high
How does urine:plasma osmolality vary between pre renal and intirnsic renal?
Urine:plasma osmolality is >2:1 in pre renal and intrinsic renal is <1:1
How does urine sodium concentration differ between pre renal and intrinsic renal?
In prerenal <15 in intrinsic renal >40
How does plasma sodium vary between pre renal and intrinsic renal?
In prerenal plasma sodium is high, in intrinsic renal it is low
How does elevation of Urea v Creatinine vary between pre renal and intrinsic renal?
Pre renal has Urea»_space; Creatinine and intrinsic renal Urea = Creatinine
Generally how to you treat pre renal, renal and post renal akis?
Pre renal - correct volume depletion and increase renal perfusion via circulatory/cardiac support
Renal - refer for biopsy and specilist support for intrinsic renal disease
Post renal - catheter, nephrostomy or urological intervention
What are the signs of hypovolaemia?
Decreased JVP, decreased urine output, decreased BP, decreased tissue turgor, increased pulse, weight loss
What are the signs of fluid overload?
Increased JVP, BP, peripheral oedema, lung crepitations, gallop rhythm
