deck_1665492 Flashcards
What is Oliguria?
• Little urine • Less than 500ml of urine/day or less than 20ml/hour
What is anuria?
• No urine • Less than 100ml of urine/day • Indicates blockage of urine flow
Give three causes of acute kidney injury
• Pre-renal disease ○ Decreased perfusion • Post-renal failure ○ Obstruction • Intrinsic Renal Failure ○ Dame to kidney
What is pre-renal acute kidney injury caused by?
• A reduction in renal perfusion • If not treated promptly acute tublar necrosis will develop
Give two over arching causes of pre-renal AKI
• Reduced effect ECF volumeImpaired renal autoregulation
Give three overarching causes of reduced effective ECF volume
• Hypovolaemia • Systemic vasodilation • Cardiac failue
Give two causes of hypovolaemia
• Blood loss • Fluid loss
Give three causes of systemic vasodilation
• Sepsis • Cirrhosis • Anaphylaxis
Give three causes of cardiac failure
• LV dysfunction • Valve diseaseTamponade
Give two causes of impaired renal autoregulation
• Preglomerular vasoconstriction • Postglomerular vasodilation
Give four causes of preglomerular vasoconstriction
• Sepsis • Hypercalcaemia • Hepatorenal syndrome • Drugs - NSAIDS
Give two causes of post glomerular vasodilation
• ACE inhibitors • Angiotensin 2 antagonists
What is post renal AKI?
• Injury as a result urine flow obstruction
What are the three sites at which urine flow can be blocked, causing post renal AKI?
• Ureters • Bladder • Urethra
What are three places obstructions can be at each particular site in post renal AKI?
• Within the lumen • Within the wall • Pressure from outside
Give four causes of blockage within the wall of the ureter, bladder or urethra
• Calculi • Blood clot • Papillary necrosis • Tumour of renal pelvis, ureter or bladder
How large must a calculi be to stop it passing?
> 10mm
Give two causes of obstruction within the wall of the ureter, bladder or urethra
• Congenital • Ureteric stricture
What does obstruction with the wall of the ureter, bladder or urethra usually cause other than acute post renal AKI?
Chronic kidney injury
Give three congenital causes of obstruction within the wall of the ureter, bladder or urethra
• Pelviureterteric neuromuscular dysfunction • Megaureter • Neurogenic bladder
Give five causes of pressure from outside causng post-renal AKI
• Prostatic hypertrophy • Malignancy • Aortic aneurysm • Diverticulitis • Accidental ligation of ureter
Give three causes of intrinsic AKI
• Acute tubular necrosis • Glomerular and arteriolar disease • Acute tubule-interstitial
What are the two main causes of acute tubular necrosis?
• Severe acute ischaemia • Toxic acute tubular necrosis
What is severe acute ischaemia caused by?
• Pre-renal fall in perfusion, causing tubular necrosis
What is toxic acute tubular necrosis?
• Nephrotoxins damage the epithelial cells lining the tubules and cause cell death • Nephrotoxins can be endogenous or exogenous
What is the most common cause of acute tubular necrosis?
• Where there is toxic acute tubular necrosis AND severe acute iscaemia
Name three endogenous nephrotoxins
BUM • Bilirubin • Urate • Myoglobin
Give four exogenous causes of ATN
• Endotoxin • X-ray contrast • Drugs • Other poisons
Give three main drugs which are exogenous nephrotoxins
• ACE inhibitors • NSAIDs • Aminoglycosides
How are NSAIDs toxic to the kidney?
• Prostaglandins usually causes vasodilation of afferent arterioles in renal autoregulation • NSAIDs inhibit prostaglandin production by inhibition of COX • Unopposed vasoconstriction of afferent arteriole occurs -> Reduced glomerular perfusion pressure -> AKI
Why are ACE inhibitors exogenous nephrotoxins?
• Angiotensin II has a key role in homeostatic control of kidney blood flow • Efferent arteriole constriction • ACE inhibtors remove this effect, decreasing GFR
What will you see in Acute Tubular Necrosis?
• Muddy brown casts in urine • Fractional excretion of Na+ >3%
How do you calculate fractional excretion of Na?
• (Na (urine) x Cr (plasma)/Cr (urine) x Na (plasma) ) x 100
Give two types of glomerular and arteriolar disease
• Primary acute glomerulonephritis • Secondary acute glomeurlonephritis
What is acute glomerulonephritis?
• Immune disease affecting glomerulus (See session 9)
Give two causes of secondary acute glomerulonephritis?
• Systemic lupus erthyrematosusVasculitis
What is acute tubulo-interstitial nephritis? Give two causes
• Inflammation of the kidney intersitium • Acute pyelonephritis and drugs
What are the three questions that should be asked when treating a patient with AKI?
• Are the kidneys underperfused? Pre-renal injury • Are nephrotoxins implicated? Direct renal injury • Is there a renal tract obstruction? Post-renal injury
If kidneys are underperfused, what are two main causes?
• Shock • Severe vascular disease
What are the three main types of shock?
• Hypovoleamic • Septic • Cardiac
What is the main cause of severe vascular disease causing AKI?
Emboli
What are three main possible nephrotoxins in direct renal injury?
• Drugs • Sepsis (endotoxins) • Myoglobin
What is one disease you can NEVER forget which also causes direct renal injury?
• UTI progressing to pyelonephritis
Give five signs of cardiac failure
• Gallop rhythm • Raised BP • Raised JVP • Pulmonary oedema – Basal crackles and dyspnoea • Peripheral oedema (Sacral/ankle)
Give five signs of sepsis
• Pyrexia and rigors • Vasodilation, warm peripheries • Bounding pulse • Rapid capillary refillHypotension
Give six signs of a urinary tract obstruction
• Anuria • Single functioning kidney • History of renal stones, prostatism or previous pelvic/abdominal surgery • Palpable bladder • Pelvic/abdominal masses • Enlarged prostate (DRE)
What signs will you see in ALL AKI?
• Increased serum urea and creatinine • Hyperkalaemia • Hyponatraemia • Hypocalcaemia • Hypophosphataemia
What investigations are peformed in AKI?
• ECG • Urine tests - Dipstick and microscopy • Soluble immunological tests • Imaging • Biopsy
What ECG changes will you see in hyperkalaemia?
• Tall T waves • Small/Absent P waves • Increase P-R interval • Wide QRS complex • ‘sine wave’ patternAsystole
What do you look for in dipstick tests?
• Blood • Protein • Leucocytes
Will there be proteinuria/haematuria/any abnormal microscopy in the urine of someone with PRE-RENAL AKI?
• No proteinuria • No haematuria • Hyaline cast in urine - Aggregations of protein seen in concentrated urine (normal sign, but will be present on every urination)
Will there be proteinuria/haematuria/any abnormal microscopy in the urine of someone with ACUTE TUBULAR NECROSIS
• No proteinuria • No haematuria • Muddy brown casts in urine
Will there be proteinuria/haematuria/any abnormal microscopy in the urine of someone withGLOMERULONEPHRITIS?
• Heavy proteinuria • Heavy haematuria • RBC casts
What soluble immunological tests can you do in AKI?
• Look for ANA (anti-nuclear antibody) ○ Indication for SLE • Look for ANCA (anti-neutrophil cytoplasmic antibody (ANCA) ○ Systemic vasculitis • Look for anti-glomerular basement membrane antibodies Goodpasture’s disease
What are two imagine techniques used in AKI?
• Ultrasound ○ Renal size ○ Hydronephrosis ○ Presence of obstruction • Chest X-ray ○ Pulmonary oedema
What is the treatment for pre-renal AKI
• Volume correction ○ Hypovolaemia -> Fluids ○ Heart failure -> Diuretic
What is the treatment for post-renal failure?
• Urological intervention to re-establish urine flow
What is the treatment for acute tubular necrosis
• Maintain good kidney perfusionAvoid nephrotoxins
When is dialysis indicated?
When kidneys can no longer adequately excrete salt, water and potassium
