AKI

Question 1

Definition

Answer 1

Significant decline in renal function over hrs or days manifesting as an abrupt and sustained ↑ in Se U and Cr

Question 2

Causes - pre-renal, renal, post

Answer 2

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

Question 3

Main cause of AKI

Answer 3

Pre-renal and ATN account for ~80%

Question 4

Presentation

Answer 4

Uraemia / Azotaemia Acidosis Hyperkalaemia Fluid overload Oedema, inc. pulmonary ↑BP(or↓) S3 gallop ↑ JVP

Question 5

Clinical Assessment main features

Answer 5

Acute or chronic Volume depleted GU tract obstruction Rare causes

Question 6

Acute or chronic assessment

Answer 6

Can’t tell for sure: Rx as acute Chronic features Hx of comorbidity: DM, HTN Long duration of symptoms Previously abnormal bloods (GP records)

Question 7

Volume depleted assessment

Answer 7

Postural hypotension ↓ JVP ↑ pulse Poor skin turgor, dry mucus membranes

Question 8

GU tract obstruction assessment

Answer 8

Suprapubic discomfort Palpable bladder Enlarged prostate Catheter Complete anuria (rare in ARF)

Question 9

Rare cause assessment

Answer 9

Assoc. ̄c proteinuria ± haematuria Vasculitis: rash, arthralgia, nosebleed

Question 10

Investigations

Answer 10

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

Question 11

Na concentration in urine - AKI

Answer 11

Pre-renal failure, urine is concentrated and Na is reabsorbed → ↑osmolality, Na <20mM

Question 12

KDIGO/ RIFLE classifcation of AKI

and complications of AKI

Answer 12

Hyperkalaemia, pulmonary oedema, bleeding

Question 13

General treatment

Answer 13

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

Question 14

Monitoring required

Answer 14

Catheterise and monitor UO

Consider CVP

Fluid balance Wt.

Question 15

Hyperkalaemia on ECG

Answer 15

ECG Features (in order)

Peaked T waves
Flattened P waves
↑ PR interval
Widened QRS
Sine-wave pattern → VF

Question 16

Hyperkalaemia treatment

Answer 16

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)

Question 17

Treating pulmonary oedema

Answer 17

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

Question 18

Treating bleeding

Answer 18

↑ urea impairs haemostasis

FFP + plats as needed

Transfuse to maintain Hb >10

Question 19

Indications for acute dialysis

Answer 19

1. Persistent hyperkalaemia (>7mM)
2. Refractory pulmonary oedema
3. Symptomatic uraemia: encephalopathy, pericarditis
4. Severe metabolic acidosis (pH <7.2)
5. Poisoning e.g barbiturates, lithium, aspirin, sulphanomides, theophylline

Question 20

Management of AKI algorithm - STEP 1 (Resuscitate and assess fluid status)

Answer 20

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

Question 21

STEP 2 - Treat life threatening complications

Answer 21

Treat life threatening complications

1. Hyperkalaemia
2. Pulmonary oedema
3. Consider rapid dialysis

Question 22

STEP 3 - Treat shock or dehydration

Answer 22

Treat shock or dehydration

1. 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

Question 23

STEP 4 - Monitor

Answer 23

Monitor

1. Cardiac monitor
2. Urinary catheter
3. Consider cVP
4. Start fluid balance chart

Question 24

STEP 5 - Look for post-renal causes

Answer 24

Look for post-renal causes

1. Palpable ± tender bladder
2. Enlarged prostate
3. Catheter in situ
4. Complete anuria

Question 25

STEP 6 - History and Investigations

Answer 25

Duration of symptoms

Co-morbidities

Previous blood results

Ix:

Bloods, ABG

Urine dip + MCS + chem

ECG

CXR and Renal US

Question 26

STEP 7 - treat sepsis

Answer 26

Blood cultures and empirical Abx

Question 27

STEP 8 - Further management

Answer 27

Call urologists if obstructed despite catheter

Care with nephrotoxic drugs: e.g. gentamicin