AKI Flashcards
what is the definition of AKI
an abrupt (<48 hrs) reduction in kidney function;
- an absolute increase in serum creatinine by >26.4 micromol/l
- or increase in creatinine by >50%
- or a reduction in urine output
can only be applied following adequate fluid resuscitation and exclusion of obstruction
what are the stages of AKI
1- (increase in serum creatinine >26 micrommol/l or increase > 1.5-1.9 x reference Cr. OR urine output <0.5 mL/hg/hr for >6 hrs)
2- increase >2-2.9 x reference SCr OR uo < 0.5 ml/kg/hr for >12 hrs
3- increase >3 x reference SCr or increase to >/= 354 micromol/L OR need for RRT. OR UO < 0.3 m/kg/hr for >24 hrs OR 12 hours anuria
what are the risk factors for AKI
patient: old age CKD diabetes cardiac failure liver disease PVD previous AKI
exposure: hypotension hypovoleamia sepsis deteriorating NEWS recent contrast medications (e.g. gentamicin)
what are the types of causes of AKI
pre renal (functional) renal (structural) post renal (obstruction)
what are the pre renal causes of AKI
hypovolaemia (haemorrhage, volume depletion (D&V, burns)
hypotension (cardiogenic shock, distributive shock (sepsis, anaphylaxis)
renal hypoperfusion (NSAIDs/ COX-2, ACEi/ARBs, heptorenal syndrome)
what is a pre renal AKI
a reversible volume depletion leading to oliguria and increase in creatinine
what is normal urine output and oliguria
normal= 0.5/kg/hr oliguria= <0.5 mls/kg/hr
what test is most sensitive for pre renal aki
urine output
what is the normal reaction to decreased renal perfusion
release of renin- increases angiotensin II- vasoconstricts efferent arteriole to maintain glomerular flow and GFR
how do ACEi affect GFR
prevent vasoconstriction of efferent arteriole in response to reduced renal perfusion- reduced GFR
how can an ACEi cause acute renal failure
as if decreased renal perfusion ACEi will exacerbate this causing a major fall in GFR
how much of cardiac output do the kidneys receive
20%
what does untreated pre renal AKI lead to
acute tubular necrosis
what is the commonest form of AKI in hospital
acute tubular necrosis
what causes acute tubular necrosis
factors leading to decreased renal perfusion
- sepsis
- severe dehydration
- rhabdomyolysis
- drug toxicity
what is the treatment for pre renal AKI
assess for hydration (BP, HR, UO, JVP, cap refil, oedema)
fluid challenge for hypovolaemia
-crystalloid (0.9% NaCl) or colloid (gelofusin)
DO NOT GIVE DEXTROSE
give bolus then reassess
if >1litre and no improvement seek help (inotropes, vasopressors)
why dont you give dextrose (hartmans) in pre renal AKI
as has potassium in it and common to get hyperkalaemic in pre renal AKI
what is renal AKI
diseases causing inflammation or damage to cells causing AKI
(blood vessels, glomerular disease, interstitial injury, tubular injury)
what are the vascular causes of renal AKI
vasculitis, renovascular disease (same as IHD but in kidneys)
what are the glomerular causes of renal AKI
glomerulonephritis
what can cause interstitial nephritis causing renal AKI
drugs- penicillin, NSAIDs, PPIs
infection (TB)
sarcoidosis
what can cause tubular injury causing renal AKI
ischaemia (prolonged renal hypoperfusion)
drugs (e.g. gentamicin)
contrast
rhabdomoyolysis
what are the symptoms of AKI
non specific: anorexia, weight loss, fatigue, lethargy N and V itch fluid overload (oedema, SOB)
what are the signs of AKI
fluid overload (HPTN, oedema, pul oedema, effusion (pleural and pulmonary)
uraemia (itch, pericarditis)
oliguria
clues to renal cause:
sore throat
strep infection
clues to renal cause:
rash
vasculitis
lupus
clues to renal cause:
joint pains
lupus
vasculitis
clues to renal cause:
haemoptysis
vasculitis
goodpastures
EGPA
churg strauss
what antibody for good pastures
anti GBM
how can urinalysis differentate AKI causes
if its a renal causes there will be blood and protein in the urine
what can cause eosinophillia
churg strauss
interstitial nephritis
what do vascular bruits suggest
renal vascular disease
what initial investigations for AKI
U&Es (marker of renal function, high potassium?)
FBC and coagulation screen (abnormal clotting- DIC, sepsis) (anaemia?)
urinalysis (haematoproteinuria)
USS- obstruction? size of kidneys- small then CKD, if one small might have renal vascular disease
immunology (ANA- lupus, ANCA- vasculitis, GBM- good pastures)
protein electrophoresis and BJP (myeloma)
what are the possible complications of AKI
hyperkalaemia fluid overload (pulmonary oedema) severe Acidosis (pH <7.15) uraemic pericardial effusion severe uraemia (Ur>40)
what can cause a post renal AKI
= obstruction of urine flow causing back pressure (hydronephrosis) and loss of concentrating ability
- stones
- cancers
- strictures
- extrinsic pressure
what is the treatment for renal AKI
fluid resus
treat underlying cause
stop nephrotoxics
dialysis if remains anuric and anaemic
what is the treatment of post renal AKI
relieve obstruction- catheter, nephrostomy
may need ureteric stenting
what is associated with hyperkalaemia
cardiac arrhythmias
what are the hyperkalaemia parameters
normal = 3.5-5
hyper = >5.5
life threatening= >6.7
what are the signs of hyperkalaemia
ECG- VT, VF, bradycardia, sine wave
muscle weakness
what ECG changes are seen in hyperkalaemia
peaked T waves flattened P wabes prolonges PR interval depressed ST segment prolonged (broad) QRS sine wave
VT, VF, bradycardia
what is the treatment for hyperkalaemia
10 mls 10% calcium gluconate (protects and stabilises the myocardium)
cardiac monitor
to move K back into cells:
insulin (actrarapid 10 units) with 50 mls 50% dextrose (30mins)
salbutamol nebs (90mins)
prevent GI absorption: calcium resonium (not in acute setting)
if they are acidotic then give sodium bicarb as acidosis can exacerbate hyperkalaemia
what are the urgent indications for haemodialysis
hyperkalaemia (>7/ >6.5 unresponsive to therapy)
severe acidosis (pH <7.15)
fluid overload
urea >40, pericardial rub/ effusion
what is the mortality of AKI
AKI alone 10-30%
AKI with one other organ dysfunction 30-50%
AKI as part of multiorgan failure 70-90%
what is the prognosis for AKI
10-15% no recovery of renal function
5-10% recover but have progressive CKD
Rest recover
what are the sick days rule to prevent AKI
if ill with D/V or fever, shakes and sweats then stop taking:
- ACEi
- NSAIDs
- duiretics
- metformin
1.40 year old male presenting with general malaise & haemoptysis (Urea 28, Creatinine 600, elevated ant-GBM)
AKI due to good pastures (renal AKI)
25 year old IVDA found collapsed at home
rhabdomyolosis
82 year old man admitted with BP 70 30, T 39, pulse 140bpm, K+ 7.0, urea 48, Cr 789, CRP 250, CXR left basal consolidation
acute tubular necrosis due to untreated sepsis (pre renal AKI)
72 year old man presenting with difficulty passing urine and reduced urine output
obstructive uropathy
name 4 drugs that cause hyperkalaemia
Spirolonolactone
Ramipril
Amiloride (potassium sparing diuretic)
Atenolol
does furosemide cause hyperkalaemia
no can cause hyPOkalaemia
80 year old male admitted with 4-5 day history of diarrhoea. On admission BP 80 40, pulse 30bpm. Bloods phone back: Na 135, K+ 8.0, Urea 50, Cr 1000, Bicarb 9
Which of the following drugs would you administer first?
A. insulin/dextrose
B. Sodium Bicarbonate
C. Salbutamol nebuliser
D. Calcium Resonium
E. Calcium Gluconate
calcium gluconate
is elevated creatinine >500 an indication for urgent dialysis
no
which drug should you avoid in a patient with AKI
NSAIDs
ACE/ARB
Diuretics
Gentamicin
Contrast
Trimethorpim- causes hypercalamia increases creatinine
Potassium sparing diuretics- hyperkalaemia
