Acute Kidney Injury Flashcards
What is the definition of acute kidney injury?
Rapid loss of glomerular filtration and tubular function over hours to days Retention of urea/creatinine Failure of homeostasis Oliguric / non-oliguric Potentially recoverable
What are the creatinine and urea levels used to define AKI?
Increase in Serum Creatinine by ≥ 26.5 μmol/l (0.3 mg/dl ) within 48 hours; or
to ≥ 1.5 times baseline, which is known or presumed to have occurred within the prior 7 days; or
Urine volume <0.5 ml/kg/h for 6 hours
(AKI 1-3)
What are some pre renal causes of AKI?
Reduce effective circulation volume
volume depletion (haemorrhage / dehydration/D and V)
Hypotension / shock (sepsis)
Congestive cardiac failure / Liver failure
Arterial occlusion
Vasomotor
NSAIDs/ACE inhibitors
What are some renal (intrinsic) causes of AKI?
Acute tubular necrosis (ATN) Ischaemic Toxin-related -Drugs (aminoglycosides / amphotericin / NSAID) -Radiocontrast -Rhabdomyolysis (Haem pigments -Snake venom / Heavy metals - Pb, Hg -Mushrooms etc Acute interstitial nephritis (many causes including drugs (PPIs)) Acute Glomerulonephritis Myeloma Intra renal vascular obstruction -Vasculitis -Thrombotic microangiopathy
What are some post renal causes of AKI?
Obstruction
- Intraluminal (calculus, clot, sloughed papilla)
- Intramural (malignancy, ureteric stricture, radiation fibrosis, prostate disease)
- Extramural (RPF, malignancy)
What is Radiocontrast nephropathy (RCN)?
AKI following administration of iodinated contrast agent
Common contributor to hospital acquired AKI
Usually transient renal dysfunction, resolving after 72h
May lead to permanent loss of function
What are risk factors for RCN?
Diabetes mellitus Renovascular disease Impaired renal function Paraprotein High volume of radiocontrast
What is multiple myeloma?
A monoclonal proliferation of plasma cells producing an excess of immunoglobulins and light chains
What are the clinical features of multiple myeloma?
Anaemia Back pain Weight loss Fractures Infections Cord compression Markedly elevated ESR Hypercalcaemia
What tests can be used to diagnose multiple myeloma?
Bone marrow aspirate - >10% clonal plasma cells
Serum paraprotein ± immunoparesis
Urinary Bence-Jones protein (BJP)
Skeletal survey - lytic lesions
What is the supportive treatment for AKI?
Fluid balance -Volume resuscitation if volume deplete -Fluid restriction if volume overload Optimise blood pressure -Give fluid /vasopressors -Stop ACE inhibitors / anti-hypertensives Stop nephrotoxic drugs -NSAIDs -Aminoglycosides
What are the five Rs for IV prescription?
Resuscitation-IV fluids urgently to restore circulation with hypovolaemia
Routine Maintenance-IV fluids if cannot take orally or enterally to meet patient maintenance requirements
Replacement-Some don’t need urgent IV resuscitation but do need IV ADDITIONAL to maintenance to correct existing deficit or ongoing abnormal EXTERNAL losses e.g. diarrhoea, fever
Redistribution-Some patients have abnormal INTERNAL fluid redistribution or abnormal fluid handling, particularly with sepsis, or major illness, cardiac, liver or renal disease e.g. tissue oedema, GI tract/ thoracic / peritoneal collection
Reassessment
What are the signs on an ECG that show hyperkalaemia?
Peaked T waves (usually the earliest sign of hyperkalaemia)
Tall tented T waves
P wave widens and flattens
PR segment lengthens
P waves eventually disappear
Prolonged QRS interval with bizarre QRS morphology
High-grade AV block with slow junctional and ventricular escape rhythms
Any kind of conduction block (bundle branch blocks, fascicular blocks)
Sinus bradycardia or slow AF
Development of a sine wave appearance (a pre-terminal rhythm)
Asystole
Ventricular fibrillation
PEA with bizarre, wide complex rhythm
What is the treatment for hyperkalaemia?
Stabilise (myocardium) -Calcium Gluconate Shift (K+ intracellularly) -Salbutamol -Insulin-Dextrose Remove -Diuresis -Dialysis -Anion exchange resins
What are advantages and disadvantages of haemodialysis?
Advantages of HD
-Rapid solute removal
-Rapid volume removal
-Rapid correction of electrolyte disturbances
-Efficient treatment for hypercatabolic patient
Disadvantages of HD
-Haemodynamic instability
-Concern if dialysis associated with hypotension, may prolong AKI
-Fluid removal only during short treatment time
