14. Acute Kidney Injury

Question 1

How do you measure kidney function?

3

Answer 1

1. Creatinine
2. eGRF (epidermal growth factor receptor)
3. Urine output

Question 2

Describe epidemiology of AKI.

3

Answer 2

1. Common:
   - 10-20% of hospitalised patients
   - 60% of AKI is present at time of hospital admission
2. Associated with harm:
   - 1 in 10 will need dialysis
   - 1/3 cases iatrogenic, and half of these preventable
   - 40% don’t survive to leave hospital, particularly the > 70s
3. Costly
4. Course and development is modifiable

Question 3

What causes AKI?
Pre-Renal (4)
Renal (9)
Post Renal (3)

Answer 3

PRE RENAL (reduced renal perfusion)

1. Hypotension
   - Severe heart failure
   - Dehydration
   - Bleeding
   - Sepsis
2. Hepatorenal syndrome
3. Renal artery stenosis
4. Renal artery clot

RENAL

1. NSAIDS
2. ACEi
3. ARBs
4. Gentamicin
5. GN/vasculitis
6. Contrast
7. Interstitial nephritis
8. Myeloma
9. Rhabdomyolysis

POST RENAL

1. Prostate enlargement
2. Renal stones
3. Pelvic cancer

Question 4

What percentage of AKI is:
Hospital acquired?
Community acquired?

Answer 4

Hospital acquired: 50.3%

Community acquired: 49.7%

Question 5

How do you prevent AKI?
(4 M’s)

What does “STOP” stand for?

Answer 5

• Risk assess for AKI: contributed by acute insult and background morbidity
• Background: elderly, CKD, cardiac failure, liver disease, diabetes, vascular disease, nephrotoxic meds

“STOP”

1. S: sepsis and hypoperfusion
2. T: toxicity
3. O: obstruction
4. P: parenchymal kidney disease

4M’s:

1. Monitor patient:
   - Obs and EWS
   - Regular bloods;
   - Maintain fluid charts;
   - Record urine output and daily weights
2. Maintain Circulation:
   - Adequate Hydration / Fluid Resuscitation
   - Oxygenation
3. Minimise Kidney Insults
   - Avoid NSAIDs, Gentamycin, iodinated contrast, HAI
4. Manage the Acute Illness
   - Recognise and treat Sepsis promptly
   - Heart failure: diuretics are usually only appropriate if hypervolaemia present…NOT to maintain urine output
   - Diuretics are NOT for urine output only
   - Stop Metformin if eGFR <30mls/min or creatinine rising
   - Suspected vasculitis or pulmonary renal syndromes need an emergency renal review
   - Ensure contrast nephropathy guidelines followed for imaging with IV contrast and avoid gadolinium based dye for MR scans if eGFR <

Question 6

What should meds should not be given during chronic kidney disease?
(4)

What medication should be given?
(1)

Answer 6

• Stop taking: ACEI, ARB, Diuretics, NSAID’s

Consider: Metformin hydrochloride
- If someone is auric, their eGFR is 0mls/min, regardless of creatinine

Question 7

How do you recognize and identify AKI?

Look at AKI Network Classification.

Answer 7

• Identify AKI (serum creatinine >1.5 x baseline) and presume normal baseline if no previous results available
• Clarify whether diagnosis likely to be pre-renal, renal or post-renal (can co-exist)
• Immune symptoms/signs:
  —> Rash, new arthritis, nasal crusting/bleeding, haemoptysis, new deafness, mouth ulcers, alopecia, iritis/episcleritis, mononeuritis multiplex or neuropathy
• Obstructive symptoms/signs: poor stream, hesitancy, frequency, nocturia, PV bleeding, stones

Question 8

What examination is performed to asses for AKI?

3

Answer 8

EXAM

1. Fluid status, BP, JVP
2. Loin tenderness, palpable bladder, rash, oedema, signs of autoimmune disease
3. Urine Dipstick: must be done in all AKI, non-dialysis CKD, DVT or PE, oedematous patient and suspected UTI

Question 9

What immunology screen is done?

4

Answer 9

Immunology Screen
1. Age >40: SPEP and UPEP

2. Haemturia: ANCA, ANA,C3, C4, HBV, HCV
3. Proteinuria: ANA, C3, C4, HBV, HIV, HCV
4. Others: cryo if rash, ENAs if ANA pos, anti-GBM if rapidly decline fxn / haematuria / lung patho

Question 10

What is contrast nephropathy?

See flow chart.

Answer 10

Impairment of renal function
- hold Diuretics , ACEI, ARB, NSAIDs on day

• 25% increase in serum creatinine

Question 11

What is hyperkalemia?

What is the treatment?
(3)

What are the complications?
(2)

Answer 11

• K>5.5
• Eliminate dietary sources
• Stop offending meds (NSAIDS, ACEI, ARBs, Amiloride, Trimethoprim, Spirinolactone)
• Recheck: beware the haemolysed potassium

TX

• Salbutamol nebulisers
  1. 10u Actrapid in 50mls 50% Dextrose: expect a reduction of approx 1mmol/L
  2. 500mls 1.26% NaHCO3 over 1h: if HCO3 < 22 and no fluid overload
  3. 10mls of 10% Calcium Gluconate (only if ECG changes): if need calcium gluconate, must do an ECG 5-10 mins later to check it has worked, if not, repeat

COMPLICATIONS

1. Acidosis
   - During emergency management
   - If pH <7.2, involve critical care
2. Pulmonary Oedema
   - Sit the patient up and give O2
   - If haemodynamically stable, 80mg IV frusemide ± infusion 10mg/hr
   - ± GTN1-10mg/hr infusion