AKI

Question 1

How common are AKIs? What is the mortality?

Answer 1

About as common as myocardial infarctions

About 1800 cases per million

Mortality is 25-50%, length of stay 13days
- Charleston comorbidity index shows more comorbidities someone has worse prognosis

Question 2

How do we measure renal function? What about in AKI cases?

Answer 2

Through renal clearance - creatinine is an exogenous product in muscle cells at a constant rate so creatinine excretion rate relatively fixed

MDRD formula (urinary creatinine time’s certain factors depending on their cause to creatinine) used to give estimated GFR

Urinary Creatinine: 100-120 mmol/ litre
Serum creatinine: 60-120 mmol/ litre
eGFR: >90ml/ min/ 1.72m2 (180L/ day)

eGFR not v helpful in AKI as takes a while for it to change so serum creatinine better test as changes first

Question 3

Definition of CKD and stages

Answer 3

Progressive loss of renal function over a period of months/ years - symptoms unspecific, generally unwell and reduced appetite

CKD 1: eGFR >90 proteinuria/ haematuria

2: >60 pro/ haem
3: 30-60 proteinuria
4: 30-15
5: <15

ESRF

Question 4

Causes of CKD

Answer 4

20% diabetic nephropathy

Hypertension

Glomerulonephritis

UTI

Polycystic kidney disease

Renal vascular disease

Question 5

Staging of AKI

Answer 5

1: 1.5-1.9 X baseline serum creatinine or _>0.3mg/dl increase, urine output- <0.5 ml/ kg/ h for 6-12hrs
2: SC- 2-2.9 X baseline, UO- <0.5 ml/kg/ h for _>12hrs
3: SC- 3 X baseline or _>4mg/dl or initiation of renal replacement therapy or in patients <18yrs decrease eGFR <35ml/ min per 1.73m2, UO - <0.3 ml/ kg/ hr for _>24hrs or Anuria for _>12 hrs

1 50% more
2 doubling, >12
3 tripling, >24

Question 6

3 categories for causes of AKI

Answer 6

Pre-renal (lack blood supply to kidney)

Renal

Post-renal (obstruction-> can’t excrete urine)

Question 7

Causes of pre-renal AKI

Answer 7

Hypo-perfusion:

Septic shock
Hypovolaemic shock
Carcinogenic shock (CVS disease most common)

Impaired renal autoregulation:
Medications e.g. NSAIDS, ACE inhibitors, cyclosporine

Question 8

How can an elderly fall lead to an AKI?

Answer 8

Elderly fall -> Rhabdomyolysis (skeletal muscle broken down) -> myoglobin blood -> inflammatory reaction in kidney as myoglobin nephrotoxic -> AKI

Symptoms rhabdomyolysis: muscle pain/ swelling/ weakness, fatigue, irregular heartbeat,
Cola- coloured urine

✅fluids

Question 9

Renal causes of AKI

Answer 9

• acute glomerulonephritis
• acute tubular necrosis
• acute interstitial nephritis
• vasculitis (-> nephritic syndrome)
• malignant hypertension
• ischaemia
• sepsis/ infection
• rhabdomyloysis
• aminoglycosides
• anti-glomerular basement membrane antibody
• myeloma
• toboimtestial diseases
• drugs: antibiotics (gentamicin, rifampicin), NSAIDS, ACE inhibitors

Question 10

Postrenal causes AKI

Answer 10

Bladder outlet obstruction

Bilateral pelvoureteral
Obstruction (or unilateral obstruction of a solitary functioning kidney)

Question 11

Management of AKI

Answer 11

urine dipstick
Electrolyte disturbance: hyperkalemia, acute ureamia

Fluid status

Consider if pt required dialysis

✅underlying cause +

Pre-renal:
✅fluids

Renal:
Immunosuppressants

Avoid nephrotoxins, restricting solutes e.g. K, PO4-