Acute Kidney Injury Flashcards
How can acute kidney injury be defined?
Abrupt (<48hrs) reduction in kidney function defined as:
An absolute increase in serum creatinine by >26.4µmol/l
OR
An Increase in creatinine by >50%
OR
A reduction in UO
How can acute kidney injury be staged?
KDIGO 3 stage classification
What are the main risk factors for AKI?
- Older Age
- CKD
- Diabetes
- Cardiac Failure
- Liver Disease
- PVD
- Previous AKI
Which exposure risk factors can increase the risk of hypovolaemia?
- Hypotension
- Hypovolaemia
- Sepsis
- Recent contrast
- Drugs
Into which three broad classifications can the causes for AKI be grouped?
Pre-renal
Renal
Post-renal
What are the 3 main pre-renal causes of AKI?
- Hypovolaemia
- Hypoperfusion
- Hypotension
How can pre-renal AKI be defined?
Reversible volume depletion leading to oliguria & increase in creatinine
What is normal urine output and from this, how is oliguria defined?
0.5ml/kg/hr
Oliguria = anything less than that
How do ACEI decrease blood pressure?
Inhibiting angiotensin II which normally constricts the efferent renal arteriole to maintain a higher blood pressure
Why should ACEI be stopped in illness?
Can cause acute kidney injury
Blood pressure will drop due to disease and also ACEI resulting in renal hypoperfusion
What is the most common form of AKI in hospital?
Acute tubular necrosis
(from untreated pre-renal AKI)
What can cause acute tubular necrosis?
Severe dehydration
Sepsis
(less common = rhabdomyolysis and drug toxicity)
How is pre-renal AKI treated?
Fluid challenge (if required from fluid assessment)
Crystalloid (0.9% NaCl) or Colloid (Gelofusin)
Bolus then reassess, generally can give up to 1litre before seeking help
In basic terms, what is renal AKI?
Diseases causing inflammation or damage to cells causing AKI
Renal AKI can manifest in which 4 ways?
- Vascular
- Glomerular disease
- Interstitial Injury
- Tubular Injury
What can cause interstitial AKI?
- Drugs
- Infection (TB)
- Systemic (sarcoid)
What can cause tubular injury in renal AKI?
- Ischaemia—prolonged renal hypoperfusion
- Drugs (gentamicin)
- Contrast
- Rhabdomyolysis
What are the symptoms of AKI?
- Anorexia, weight loss, fatigue, lethargy
- Nausea & Vomiting
- Itch
- Fluid overload (oedema, SOB)
They are non-specific symptoms
Which signs are associated with AKI?
- Fluid overload (hypertension, Oedema, Pulmonary oedema, effusions (pleural & pulmonary))
- Uraemia (itch, pericarditis)
- Oliguria
Which electrolyte is important to measure in AKI?
Potassium
(high shows poor kidney function)
What are the main life-threatening associations with AKI?
- Hyperkalaemia
- Fluid Overload (Pulmonary oedema)
- Severe Acidosis (pH < 7.15)
- Uraemic pericardial effusion
- Severe Uraemia (Ur >40)
Wnhat is post-renal AKI?
AKI caused by obstruction distal to the kidneys
Back-pressure of urine causes hydronephrosis and failure of urine concentration
What are the main causes of post-renal AKI?
Stones, Cancers, Strictures, Extrinsic Pressure
How is post-renal AKI treated?
Relieve obstruction
- Catheter
- Nephroscomy
What is the normal range for potassium in the blood?
3.5-5mmol/l
At which level is hyperkalaemia classified as life threatening?
>6.5mmol/l
(>5.5mmol/l is classed as hyperkalaemia)
How can hyperkalaemia be assessed?
ECG
Muscle weakness
How can hyperkalaemia present on ECG?
- Tall T waves
- Loss of P waves
- Bradycardia
- Wide QRS
What is the treatment for hyperkalaemia?
Protect myocardium
- 10mls 10% calcium gluconate (2-3mins)
Move K+ back into the cells
- Insulin (actrapid 10units) with 50mls 50% dextrose (30 mins)
- Salbutamol Nebs (90 mins)
Prevent absorption from GI tract
- Calcium resonium (NOT in the acute setting)
Acidosis
- Sodium bicarbonate
What are the key indications for haemodialysis?
- Hyperkalaemia (>7 or >6.5 and unresponsive to medical therapy)
- Severe Acidosis (pH < 7.15)
- Fluid overload
- Urea >40, pericardial rub/effusion
