Acute Kidney Injury Flashcards
Definition of Acute Renal failure?
Rapid loss of GFR and tubular function - hours to days
Urea/creatinine retention
Oliguric/non-oliguric
What is the biochemical definition of acute renal failure?
Serum creatinine ↑: >26.5umol within 48hrs or >1.5x baseline within 7 days and Urine volume <0.5ml/kg/h for 6hrs
How is AKI stage 1 defined?
Serum creatinine ↑: >26.5umol within 48hrs or >1.5x baseline within 7 days and Urine volume <0.5ml/kg/h for 6hrs
How is AKI stage 2 defined?
Serum creatinine ↑:
2-3x baseline
and
Urine volume <0.5ml/kg/h for 12hrs
How is AKI stage 3 defined?
3x baseline or Increase to >354umol or Initiation of RRT and <0.3ml/kg for 24hrs or Anuria for 12hrs
How common is AKI?
1 in 7
What factors can increase the risk of AKI?
Comorbidities
Old Age
How does AKI present?
AEIOU A - acidosis E - electrolyte disturbance I - intoxication O - overload U - Uraemia
What is the mortality in dialysis-requiring AKI?
45-70%
What is the mortality in non-dialysis requiring AKI?
AKI 1 - 8%
AKI 2 - 25%
AKI 3 - 33%
What are the long term outcomes of AKI?
Death
CKD
Dialysis
CV events
What are the main types of AKI?
Pre-renal (blood flow to kidney)
Renal (intrinsic)
Post-renal (obstruction of urine)
What are the causes of pre-renal AKI?
Volume depletion Hypotension Shock Congestive HF Liver failure Arterial occlusion Vasomotor
What drugs can cause vasomotor pre-renal AKI?
NSAIDs
ACEi
What are the causes of intrinsic renal AKI?
Acute Tubular Necrosis Toxins Acute interstitial nephritis Acute glomerulonephritis Myeloma Intra-renal vascular obstruction
Which toxins are commonly associated with intrinsic AKI?
Amphotericin, aminoglycosides, NSAIDs Radiocontrast (iodinated) Rhabdomyolysis Snake venom Heavy metals Mushrooms
What are the causes of post-renal AKI?
Obstruction
Intraluminal
Intramural
Extramural
What are the intralumal causes of post-renal AKI?
Calculus
Clout
Sloughed papilla
What are the intramural causes of post-renal AKI?
Malignancy
Ureteric stricture
Radiation fibrosis
Prostate disease
What are the extramural causes of post-renal AKI?
RPF
Malignancy
What is the course of acute ischaemic renal injury?
Initiation
Maintenance (established parenchymal damage, maximally oliguric, 1-2 wks)
Recovery
What is the cause of excessive recovery diuresis?
GFR recovering faster than tubule resorptive capacity
How does radiocontrast nephropathy present?
AKI following iodinated contrast administration
Transient renal dysfunction
72hr resolution
May be permanent
What are the risk factors for radiocontrast nephropathy?
DM Renovascular disease Impaired renal function Paraprotein Large volume of contrast
What is multiple myeloma?
Monoclonal proliferation of plasma cells producing excess Ig, light chains
How does myeloma typically present?
Anaemia Back pain Weight loss Fractures Infections Cord compression Marked elevated ESR Hypercalcaemia
Myeloma is common in who?
the elderly
How is myeloma diagnosed?
Bone marrow aspirate
Serum paraprotein
Urinary Bence-Jones protein
Skeletal survey
How does renal failure present in myeloma?
Cast nephropathy Light chain nephropathy Amyloidosis Hypercalcaemia Hyperuricaemia
What blood tests should be performed in suspected AKI?
FBC U&E Bicarb LFTs Clotting Blood gas (ANCA/Ig/C3,C4)
What urine tests should be performed in suspected AKI?
Urine dip
Urine PCR
Urine bence jones protein
What are the risk factors for AKI?
Age >75 Previous AKI HF Liver disease CKD DM Vascular disease
What are the AKI risk events?
Sepsis Toxins Hypotension Hypovolaemia Major surgery
What should you consider in patients with one or more risk event/factor?
STOP S - sepsis T - Toxins O - Optimise BP/volum P - prevent harm
What steps should be taken to prevent AKI?
Avoid dehydration Avoid nephrotoxins Review clinical status, U&E, fluid balance Hold medications Treat sepsis
What should the next step be in sepsis?
Sepsis 6 Blood cultures Urine output monitoring, U&E Fluids Antibiotics Lactate O2 saturation
What should be considered in hypotensive patients?
Withdraw:
- Antihypertensives
- Diuretics
Vasopressors
What are the insensible losses of water in the body?
Skin
Lungs
What ECG changes are seen in hyperkalemia?
Peaked, tented T waves P-wave widens then disappears PR lengthens Prolonged QRS Bradycardia High grade AV block
How is Hyperkalemia treated?
Stabilise Myocardium - Calcium Gluconate Shift K+ intracellularly - Insulin-dextrose - Salbutamol Remove - Diuresis - Dialysis - Anion exchange resins
What is the antidote to morphine?
Naloxone
What is the antidote to digoxin?
Digibind
What are the indications for dialysis in AKI?
Acidosis (↓HCO3-) Electrolytes (↑K+) Intoxication Overload (Pulmonary oedema) Uraemia (pericarditis)
What are the advantages of haemodialysis?
Fast solute/volume removal
Fast correction of electrolytes
Efficient for hypercatabolic patients
What are the disadvantages of haemodialysis?
Haemodynamic instability
Concern with hypotension
Fluid removal only during short treatment time
What are the advantages of continuous therapy?
Slow removal = greater haemodynamic stability
Less fluctuation in volume/solute control
What are the disadvantages of continuous therapy?
Continuous anticoagulation
Delay weaning
Hypercatabolic Pt - less clearance
