Acute kidney injury Flashcards
(15 cards)
Define acute kidney injury
A rapid reduction in kidney function as measured by creatinine or decreased urine output
- Aka acute renal failure
Broad classification of acute kidney injury
PRERENAL (70% - most common cause of AKI in community)
- decreased renal perfusion
RENAL
- Process within kidney
- ATN (most common cause of AKI in hospital)
POSTRENAL
- Inadequate drainage of urine
Pre-renal causes of AKI
HYPOVOLAEMIA
- GIT
1. Vomiting
2. Diarrhoea
3. Enterocutaneous fistula - Renal loss
1. Diuretics
2. DM (osmotic diuresis - hyperglycaemia)
3. Hyperclacemia
4. Nephrogenic diabetes - Blood loss
- Decreased intake
THIRD SPACING
- Heart failure
- Cirrhosis
- Nephrotic syndrome
LOW SYSTEMIC VASCULAR RESISTANCE
- Anti-hypertensives
- Liver failure
- Hypovolaemic shock
- Distributive shock: septic
LOW CARDIAC OUTPUT
- Heart failure
- Cardiogenic shock
- ACS
- Tension pneumothorax
- PE
- Hypothyroidism
LOCAL RENAL HYPOPERFUSION
- Drugs: NSAIDs, COX-i, ACEi, norepinephrine
- Renal artery stenosis
- Expanding AAA causing renal artery obstruction
- Hepatorenal syndrome
Renal causes of AKI
VASCULAR
- Vasculitis
- Malignant HTN
- Thrombotic microangioapthy
- Cholesterol emboli
- Large vessel disease
GLOMERULAR
- GN
- Medications - NSAIDs
TUBULAR
- ATN
- Medications - NSAIDs, ahminoglycosides, quinolone, carbamazepine, methotrexate
INTERSTITIAL
- AIN
- Medications - betalactams, sulphonamides, fluroquinolones, diuretics
Post-renal causes of AKI
URETERAL
- Intraluminal obstruction
1. Nephrolithiasis - Extraluminal obstruction
1. Blood clot
2. Pelvic malignancy
3. Pregnancy
BLADDER or URETHRAL
- Urethral stricture
- Urethral valves
- Benign prostatic hyperplasia
- Prostate cancer
- Bladder tumor (e.g. TCC)
- Neurogenic bladder
- Anticholinergic meds
Hx of AKI
- May be asymptomatic
- Anuria, oliguria, polyuria
- Change in mental status, confusion
- Lethargy
- Nausea and vomiting
- Swelling
HPC
- Hx of vomiting, diarrhoea, blood loss or shock
- Prolonged immoblisiaton (rhabdomyolysis)
PMHX
- Heart
- Lungs
- Liver
- DM
- HTN
Meds
- Diuretics
- Anti-hypertensives
- NSAIDs
- Antibiotics
PE with AKI
- G.I. altered mental status
- Vitals: BP, HR, fever
- Hydration status
- Raised JVP
- CVS: heart failure, murmurs
- Resp: heart failure
- Abdo: bruits, masses, distended bladder, ascites
- Peripheral oedema
Ix of AKI
- CBE
- EUC
- Ca2+, phosphate
- Urinalysis MC&S: sediments, casts, crystals
- Foley catheters (r/o bladder outlet obstruction
- Abdo US: kidney size, post renal obstruction
- Renal biopsy
Clinical clues to pre-renal cause of ATI
- Decr BP, incr HR, orthostatic hypotension
- Incr urea»_space; incr creatinine
- Urine Na <10-20mmol/L
Clinical clues to renal cause of ATI
- Urinalysis positive for casts
Clinical clues to post-renal cause of ATI
- Known solitary (one) kidney
- Older man
- Recent retroperitoneal surgery
- Anuria
- Palpable bladder
- Abdo US: hydronephrosis
Tx of pre-renal AKI
- Fluids resus
- Improve CO
- Hold ACEi and ARB
Tx of renal AKI
Address reversible renal causes:
- Discontinue nephrotoxic drugs
- Treat infection
- Optimize electrolyes
Tx of post-renal AKI
- Treat with Foley catheter,
2 Indwelling bladder catheter - Nephrostomy
- Stenting
Describe the triplle whammy and the pathophysiology of each drug
- ACEi –> blocks angiotensin II –> dilates efferent arteriole –> increased efferent pressure –> impedes outflow of glomerulus
- NSAID –> inhibits COX-1, COX-2 –> inhibits renal prostaglandins –> constrict renal afferent arteriole –> decr. renal perfusion
- Diuretic –> volume depletes –> decr. renal perfusion
