AKI Flashcards
Definition
Significant decline in renal function over hrs or days manifesting as an abrupt and sustained ↑ in Se U and Cr
Causes - pre-renal, renal, post
Pre-renal: commonest cause Shock or renovascular compromise (e.g. NSAIDs, ACEi) Renal ATN: Ischaemia: shock, HTN, HUS, TTP Direct nephrotoxins: drugs, contrast, Hb Acute TIN: drug hypersensitivity Nephritic syndrome Post-renal: SNIPPIN
Main cause of AKI
Pre-renal and ATN account for ~80%
Presentation
Uraemia / Azotaemia Acidosis Hyperkalaemia Fluid overload Oedema, inc. pulmonary ↑BP(or↓) S3 gallop ↑ JVP
Clinical Assessment main features
Acute or chronic Volume depleted GU tract obstruction Rare causes
Acute or chronic assessment
Can’t tell for sure: Rx as acute Chronic features Hx of comorbidity: DM, HTN Long duration of symptoms Previously abnormal bloods (GP records)
Volume depleted assessment
Postural hypotension ↓ JVP ↑ pulse Poor skin turgor, dry mucus membranes
GU tract obstruction assessment
Suprapubic discomfort Palpable bladder Enlarged prostate Catheter Complete anuria (rare in ARF)
Rare cause assessment
Assoc. ̄c proteinuria ± haematuria Vasculitis: rash, arthralgia, nosebleed
Investigations
Bloods: FBC, U+E, LFT, glucose, clotting, Ca, ESR ABG: hypoxia (oedema), acidosis, ↑K+ GN screen: if cause unclear Urine: dip, MCS, chemistry (U+E, PCR, osmolality, BJP) ECG: hyperkalaemia CXR: pulmonary oedema Renal US: Renal size, hydronephrosis
Na concentration in urine - AKI
Pre-renal failure, urine is concentrated and Na is reabsorbed → ↑osmolality, Na <20mM
KDIGO/ RIFLE classifcation of AKI
and complications of AKI
Hyperkalaemia, pulmonary oedema, bleeding

General treatment
Identify and Rx pre-renal or post-renal causes
Urgent US
Rx exacerbating factors: e.g. sepsis
Give PPIs
Stop nephrotoxins: NSAIDs, ACEi, gent, vanc Stop metformin if Cr > 150mM
Monitoring required
Catheterise and monitor UO
Consider CVP
Fluid balance Wt.
Hyperkalaemia on ECG
ECG Features (in order)
Peaked T waves
Flattened P waves
↑ PR interval
Widened QRS
Sine-wave pattern → VF
Hyperkalaemia treatment
10ml 10% calcium gluconate
50ml 50% glucose + 10u insulin (Actrapid) over 5-15 units
Salbutamol 5mg nebulizer
Consider sodium bicarb (don’t give in the same line as calcium = prescipitate)
Haemofiltration (usually needed if anuric)
Treating pulmonary oedema
Sit up and give high-flow O2
Morphine 2.5mg IV (± metoclopramide 10mg IV)
Frusemide 120-250mg IV over 1h
GTN spray ± ISMN IVI (unless SBP <100)
If no response consider:
CPAP
Haemofiltration / haemodialysis ± venesection
Treating bleeding
↑ urea impairs haemostasis
FFP + plats as needed
Transfuse to maintain Hb >10
Indications for acute dialysis
- Persistent hyperkalaemia (>7mM)
- Refractory pulmonary oedema
- Symptomatic uraemia: encephalopathy, pericarditis
- Severe metabolic acidosis (pH <7.2)
- Poisoning e.g barbiturates, lithium, aspirin, sulphanomides, theophylline
Management of AKI algorithm - STEP 1 (Resuscitate and assess fluid status)
Resuscitate and assess fluid status
A
B
C: assess fluid statius
CV - postural bp, JVP, HR
Tissues - cold/warm hands, skin tugor, mucus membranes, cap refill
End-organ: mental state, urine output
STEP 2 - Treat life threatening complications
Treat life threatening complications
- Hyperkalaemia
- Pulmonary oedema
- Consider rapid dialysis
STEP 3 - Treat shock or dehydration
Treat shock or dehydration
- Fluid challenge (500ml in normal patient or 250ml in patients with heart failure over 15 mins for up to 2L)
Aim for CVP of 5-10cm
Once repleted continue at 20ml + UO/h
If not repleted - call for specialist
STEP 4 - Monitor
Monitor
- Cardiac monitor
- Urinary catheter
- Consider cVP
- Start fluid balance chart
STEP 5 - Look for post-renal causes
Look for post-renal causes
- Palpable ± tender bladder
- Enlarged prostate
- Catheter in situ
- Complete anuria
STEP 6 - History and Investigations
Duration of symptoms
Co-morbidities
Previous blood results
Ix:
Bloods, ABG
Urine dip + MCS + chem
ECG
CXR and Renal US
STEP 7 - treat sepsis
Blood cultures and empirical Abx
STEP 8 - Further management
Call urologists if obstructed despite catheter
Care with nephrotoxic drugs: e.g. gentamicin