Acute Kidney Injury Flashcards
What is the rough definition of AKI and the different stages?
It is the decline of renal excretory function over hours/days with a rise in serum urea and creatinine.
Stage 1- Creatinine raised by 1.5-1.9 of baseline or urine output <0.5ml/kg/hr for 6 hours.
Stage 2 - Serum creatinine 2x the baseline or urine output <0.5ml/kg/hr for24 hours.
Stage 3 - Serum creatine 3x the baseline or creatinine >354 or or urine output <0.3ml/kg/hr for 24 hours.
What is oliguria?
Infants - Less than 1mL/kg/hour
Adults - Less than 0.5mL/kg/hour.
Roughly less than 400-500ml per 24 hours
What are the causes of an AKI?
Prerenal,
Renal
Post renal
What are the pre renal causes of an aki?
Hypovolaemia and hypotension (could be due to diarrhoea/vomiting, inadequate fluid intake, blood loss)
Reduced effective circulatory volume (cardiac failure or sepsis)
Drugs such as ACEi or NSAIDs.
Renal artery stenosis
What are the renal causes of an AKI?
Glomerular, interstitial, vascular or tubular.
1. Glomerulonephritis,
2. Acute tubular necrosis,
3. Acute intertitial nephritis
4. Rhabdomyolysis,
5. Tumour lysis syndrome,
5. Vasculitis
What are the post renal casues of an AKI?
Obstruction eg, kidney stones in ureter, BPH, external compression of the ureter
What is acute tubular necrosis?
Necrosis of tubular epithelial cells - reversible
What are the causes of acute tubular necrosis?
Ischaemia: shock or sepsis.
Nephrotoxins: Aminoglycosides, myoglobin, NSAIDs, radiocontrast agents and lead
What are the features of acute tubular necrosis?
AKI and muddy brown casts in the urine
What are the cause’s of acute interstitial nephritis?
Drugs: Penicillin, rifampicin, NSAIDs, allopurinol, furosemide.
Systemic disease: SLE, sarcoidosis, Sjogren’s syndrome.
Infection: Hanta virus, staphylococci
What are the features of acute interstitial nephritis?
Fever, rash, arthralgia,
Eosinophilia,
Mild renal impairment,
Hypertension
What are the investigations for acute interstitial nephritis?
Sterile pyuria and white cell casts
What are some risk factors for development on an AKI?
CKD,
Organ failure/chronic disease,
History of AKI,
Nephrotoic drugs,
Iodinated contrast,
age > 65 years old,
oliguira
What are the signs and symptoms of an AKI?
Reduced urine output,
Pulmonary and peripheral oedema,
Arrythmias secondary to changes in potassium.
Features of uraemia
What are the investigations for an AKI?
U&Es
Urinalysis,
ABG- look for acidosis
ECG to look for hyperkalaemia changes
Imaging - Renal ultrasound if unknown cause or at risk of obstruction
What drugs are usually safe to continue in AKI?
- Paracetamol
- Warfarin
- Statins
- Aspirin (at a cardioprotective dose of 75mg od)
- Clopidogrel
- Beta-blockers
What drugs should be stopped in an AKI?
- NSAIDs (except if aspirin at cardiac dose e.g. 75mg od)
- Aminoglycosides
- ACE inhibitors
- Angiotensin II receptor antagonists
- Diuretics
What drugs might have to be stopped in an AKI?
Metformin,
Lithium,
Digoxin
What is the management of hyperkalaemia?
Anyone with potassium > 6.5 or with ECG changes should give IV calcium gluconate and insulin/dextrose infusion.
Further management: Stop exacerbating drugs (ACEi), lower body potassium with calcium resonium, loop diuretics or dialysis
What is the diagnostic criteria for an AKI?
- Rise in creatinine of 26+ in 48 hours.
- 50% plus rise in creatinine over 7 days.
- Fall in urine output to below 0.5ml/kg/hour for more than 6 hours
What patient’s with an AKI should be referred to a nephrologist?
Stage 3 AKI
Renal transplant,
ITU patients with unknown cause of AKI,
Vasculitis/glomerulonephritis/myeloma etc,
AKI with no known cause,
Inadequate response to treatment,
How can you differentiate between AKI and CKD?
Renal US. CKD will almost always have small kidneys (normal is 10-13cm)except for: AD polycystic kidney disease, diabetic nephropathy, amyloidosis, HIV associated nephropathy.
Or if patient is hypocalcaemia (suggests CKD)
What are the indications for acute dialysis?
Acidosis
Electrolyte imbalance (resistant hyperkalaemia),
Intoxication (drug overdose),
Oedema (refractory pulmonary oedema)
Uraemia (encephalopathy or pericarditis)
What is the managements of an AKI?
A-E exam.
Address immediate threats eg, acidosis, hypovolaemia, hyperkalaemia, sepsis.
Identify and treat underlying cause.
Supportive management: IV fluids, stop nephrotoxic drugs and relieve obstruction via catheter.
Monitor patient.
Review medications
Which patient’s with an AKI should be admitted to hospital?
stage 3 AKI,
No identifiable cause,
Obstructed or infected AKI,
Sepsis.
Evidence of hypovolaemia or need for IV fluids
What are the effects of giving a statin and a macrolide?
Increases level of statins which can cause rhabdomyolysis - AKI
What is involved in a GN screen?
ANA, ANCA, C3/4, anti-gbm, rh factor
