Acute Kidney Injury (AKI) Flashcards
Define Acute Kidney Injury (AKI)?
An abrupt loss of kidney function resulting in the retention of urea and other nitrogenous waste products and dysregulation of extracellular volume and electrolytes
What is the KDIGO classification of AKI?
Increase in serum creatinine > 26 µmol/L within 48 hrs
Increase in serum creatinine to > 1.5 times baseline within the preceding 7 days
Urine volume < 0.5 ml/kg/hr for 6 hours
What is the Aetiology of AKI?
Pre-Renal (90%)
Intrinsic Renal
Post-Renal (due to obstruction)
What are the Pre-Renal causes of AKI?
Hypovolaemia (e.g haemorrhage, severe vomiting)
Heart Failure
Cirrhosis
Nephrotic Syndrome
Hypotension (e.g shock, sepsis, anaphylasis)
Renal Hypoperfusion (e.g NSAIDs, ACE inhibitors, ARBs, renal artery stenosis)
What are the intrinsic renal risk factors of the AKI?
Glomerular - Glomerulonephritis, haemolytic uraemic syndrome
Tubular- acute tubular necrosis
Interstitial- acute interstitial nephritis (e.g. NSAIDs, Autoimmune)
Vasculitides (e.h. Wegener’s granulomatosis)
Eclampsia
What are the Post-Renal causes by AKI?
Calculi
Urethral Stricture
Prostatic Hypertrophy or malignancy
Bladder Tumour
What are the risk factors of AKI?
Age
Chronic Kidney Disease
Comorbidities (e.g. heart failure)
Sepsis
Hypovolaemia
Use of Nephrotoxic Medications
Emergency Surgery
Diabetes Mellitus
What is the epidemiology of AKI?
15% of adults admitted to hospital will develop an AKI
Most common in the elderly
What are the presenting symptoms of AKI?
Depends on Underlying CAUSE
Oliguria/anuria (abrupt anuria suggests post-renal obstruction)
Nausea/Vomiting
Dehydration
Confusion
What are the signs of AKI on physical examination?
Hypertension
Distended Bladder
Dehydration - postural hypotension
Fluid overload (in heart failure, cirrhosis, nephrotic syndrome) - raised JVP, pulmonary and peripheral oedema
Pallor, rash, brusing (vascular disease)
What are the appropriate investigations for AKI?
Urinalysis
Bloods
Ultrasound
Other Imaging:
CXR - pulmonary oedema
AXR - renal stones
What is the Urinalysis you can do for AKI?
Blood - suggests nephritic cause
Leucocyte Esterase and nitrites - UTI
Glucose
Protein
Urine Osmolality
What are the Bloods you can do for AKI?
FBC
Blood FIlm
U&Es
Clotting
CRP
What are the Immunology Bloods you can do for AKI?
- Serum Immunoglobulins and protein electrophoresis for multiple myeloma
- Also check for Bence-Jonce proteins in the urine
- ANA- associated with SLE
- Also check anti-dsDNA antibodies (high in active lupus)
- Complement Levels - low in active lupus
- Anti-GBM antibodies - Goodpasture’s syndrome
- Antistreptolysin-O antibodies -high after Streptococcal infection
What are the Virology tests you can do for AKI?
Check for Hepatitis
Check for HIV
Why would you do an US for AKI?
Check for post-renal cause
Look for hydronephrosis
What is the general management for AKI?
Treat the cause
Monitor Serum Creatinine, Sodium, Potassium, Calcium, Phosphate and Glucose
Identify and treat infection
Urgent relief of urinary tract obstruction
Refer to nephrology if intrinsic renal disease is suspected
What are the four main components to management?
Protect Patient from hyperkalaemia (calcium gluconate)
Optimise fluid balance
Stop Nephrotoxic Drugs
Consider for dialysis
When is the Renal Replacement Therapy (RRT) considered?
Hyperkalaemia refractory to medical management
Pulmonary Oedema refractory to medical mnagement
Severe metabolic Acidaemia
Uraemic Complications
What are the possible complications of AKI?
Pulmonary oedema
Acidaemia
Uraemia
Hyperkalaemia
Bleeding
What is the prognosis for patients with AKI?
Inpatient Mortality varies depending on cause and comorbities
Patients who develop AKI are at increased risk of developing CKD
What are the indicators of poor prognosis?
Age
Multiple Organ Failure
Oliguria
Hypotension
CKD
