AKI Flashcards
Describe 3 clinical definitions of acute kidney injury
- Increase in serum creatinine by >26.5micromol/L (>0.3mg/dL) within 48h
- OR increase in serum creatinine >1.5x baseline known or suspected to have occurred within prior 7d
- OR urine output <0.5mL/kg/h for 6h
Causes of AKI
Describe pre-renal [2], intrinsic [4] and post-renal causes [3]
Pre-renal: hypotension, renal artery stenosis Intrinsic renal: direct parenchymal injury - Acute tubular necrosis - Glomerular - Interstitial eg drugs, ca - Vascular eg HUS Post-renal: UTO - Luminal eg stones - Mural eg ca, BPH - Extrinsic eg pelvic mass
Risk factor [7]
75y/o CKD, HF, PAD Chronic liver disease, DM Sepsis Poor fluid intake or increased losses PMHx UT symptoms, PMHx gout Nephrotoxic drugs (especially newly started), other nephrotoxins
Presentation systemic sx [3]
Signs [1]
*Presentation is highly dependent on the underlying cause
Systemic: rash, arthralgia, fever
Fluid status: overload and depletion signs
Investigations [6]
What 3 imaging you would do and why?
U&E, Cr (ratio ddx between pre-renal and intrinsic)
Urinalysis, C&S, Na conc, Bence Jones
ECG (hyperkalemia)
ABG and VBG
LFT
FBC & blood film (HUS)
Imaging: CXR (fluid overload), renal USS if obstruction, CTKUB if nephrosis
Management
Immediate management [3]
Subsequent management [5]
Immediate: ABCDE
- Volume status: catheterize to monitor output, aim for euvolemia
- VBG, ECG to exclude hyperkalemia
Subsequent:
- Fluid therapy (avoid K unless hypokalemic)
- Stop nephrotoxic drugs
- Monitor
- Nutrition
- Manage underlying cause
What are things to monitor in subsequent management? [3]
Consider ICU or HDU
Hourly BP, pulse, JVP and urine output
Daily U&E and creatinine; daily weight and fluid balance chart
Who to refer to? [2]
referral to renal medicine if signs of tubular, glomerular or multi-system disease; referral to urology if obstruction
Complications of AKI [6]
Hyperkalemia Uremia Pulmonary edema Metabolic acidosis CKD ESRF
RRT in AKI [6]
Refractory pulmonary edema Persistent hyperkalemia Severe metabolic acidosis Uremic encephalopathy Pericarditis BLAST drug overdose
What is BLAST drug overdose
[5]
Stands for: Barbiturates Lithium Alcohol Ethylene glycol Salicylates Theophylline
How do we stage AKI?
RIFLE. A progressive set of criteria to monitor the severity of Kidney Injury
What does the R in rifle mean? [3]
RIFLE - AKI staging
R = Risk:
1) 1.5 serum creatinine
2) OR 25% loss of GFR
3) <0.5ml/Kg/hr UO for 6 hours
What does the I in RIFLE mean? [3]
I - Injury
1) 2x serum creatinine
2) Or 50% loss of GFR
3) <0.5ml/Kg/Hr UO for 12 hours
What does the F in RIFLE mean? [4]
Failure
1) 3x serum creatinine
2) Or 75% loss in GFR
3) Or UO <0.3ml/Kg/hr for 24 hours
4) Or Anuria for 12 hours
What does the L in RIFLE mean? [2]
Loss
1) Persistent AKI
2) Or complete loss of function >4 wks
What does the E mean? [2]
End Stage Disease
Completely loss of kidney function >3 months
Hyperkalemia mx
- Stabilise myocardium with calcium gluconate
- Shift K intracellularly – salbutamol, insulin-dextrose
- Remove through diuresis, dialysis, calcium resonium
- If acidotic, use sodium bicarbonate
Acute tubular necrosis (ATN) is the most common cause of acute kidney injury (AKI) seen in clinical practice.
Causes [2]
ischaemia
- shock
- sepsis
nephrotoxins
Name nephrotoxins that can cause ATN [4]
aminoglycosides -mycins
myoglobin secondary to rhabdomyolysis
radiocontrast agents
lead
Features of AKI in ATN [4]
raised urea
raised creatinine
raised potassium
muddy brown casts in the urine
Acute interstitial nephritis is another mechanism of AKI [3]
- Drugs: the most common cause, particularly antibiotics
- systemic disease: SLE, sarcoidosis, and Sjögren’s syndrome
- infection: Hanta virus , staphylococci
Drugs that can cause acute interstitial nephritis [5]
penicillin rifampicin NSAIDs allopurinol furosemide
Pathophysiology of Acute interstitial nephritis [2]
histology:
- marked interstitial oedema
- and interstitial infiltrate in the connective tissue between renal tubules
Clinical presentation of Acute interstitial nephritis [4]
Urinalysis [2]
fever, rash, arthralgia
eosinophilia
mild renal impairment
hypertension
Investigations
- sterile pyuria
- white cell casts
