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Renal + Urology > Acute Kidney Injury > Flashcards

Acute Kidney Injury Flashcards

1
Q

NICE Criteria For AKI

A

Rise in creatinine of ≥ 25 micromol/L in 48 hours

Rise in creatinine of ≥ 50% in 7 days

Urine output of < 0.5ml/kg/hour for > 6 hours

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2
Q

Consider the possibility of an acute kidney injury in patients that are suffering with an acute illness such as infection or having a surgical operation. Risk factors that would predispose them to developing acute kidney injury include:

A

Chronic kidney disease

Heart failure

Diabetes

Liver disease

Older age (above 65 years)

Cognitive impairment

Nephrotoxic medications such as NSAIDS and ACE inhibitors

Use of a contrast medium such as during CT scans

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3
Q

Pre-renal Causes

A

Pre-renal pathology is the most common cause of acute kidney injury. It is due to inadequate blood supply to kidneys reducing the filtration of blood. Inadequate blood supply may be due to:

HYPOVOLAEMIA (D+V, burns, haemorrhage)

REDUCED CARDIAC OUTPUT (MI, cardiogenic shock)

SYSTEMIC VASODILATION (sepsis, drugs)

RENAL VASOCONSTRICTION (nsaids, ace-inhibitors, hepatorenal syndrome)

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4
Q

Renal Causes

A

This is where intrinsic disease in the kidney is leading to reduced filtration of blood. It may be due to:

GLOMERULAR (Glomerulonephritis)

TUBULAR DISEASE (acute tubular necrosis, infection)

INTERSTITIAL (Interstitial nephritis, infection, ischaemia, nephrotoxins)

VASCULAR (vasculitis, DIC, TTP, HUS)

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5
Q

Post-renal Causes

A

Post renal acute kidney injury is caused by obstruction to the outflow of urine from the kidney, causing back-pressure into the kidney and reduced kidney function. This is called an obstructive uropathy. Obstruction may be caused by:

Kidney stones

Masses such as cancer in the abdomen or pelvis

Ureter or uretral strictures

Enlarged prostate or prostate cancer

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6
Q

Investigations for AKI

A

Blood tests:
- serum creatinine
- GFR (90-120ml/min normal)
- BUN (blood, urea, Nitrogen)
- U & Es (electrolyte imbalance?)
+FBC
+coagulation screen
+LFT

Urinalysis (urine dip) for protein, blood, leucocytes, nitrites and glucose.
- MCS = microscopy, culture + sensitivity

+ MONITOR URINE OUTPUT

Leucocytes and nitrites suggest infection
Protein and blood suggest acute nephritis (but can be positive in infection)
Glucose suggests diabetes

Ultrasound of the urinary tract is used to look for obstruction. It is not necessary if an alternative cause is found for the AKI.

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7
Q

Management AKI

A

Prevention of acute kidney injury is important. This is achieved by avoiding nephrotoxic medications where possible and ensuring adequate fluid input in unwell patients, including IV fluids if they are not taking enough orally.

The first step to treating an acute kidney injury is to correct the underlying cause:

  • Fluid rehydration with IV fluids in pre-renal AKI
  • Stop nephrotoxic medications such as NSAIDS and antihypertensives that reduce the filtration pressure (i.e. ACE inhibitors)
  • Relieve obstruction in a post-renal AKI, for example insert a catheter for a patient in retention from an enlarged prostate

In a severe acute kidney injury or where there is doubt about the cause or complications, input from a renal specialist is required. They may need dialysis.

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8
Q

Complications AKI

A

Hyperkalaemia

Fluid overload, heart failure and pulmonary oedema

Metabolic acidosis

Uraemia (high urea) can lead to encephalopathy or pericarditis

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9
Q

Most common cause of an AKI?

A

Sepsis (pre-renal)

(systemic vasodilation)

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10
Q

Investigations for pre-renal AKI

A

HPC
Blood pressure, Capillary refill
Inflammatory markers, blood cultures
ECG, troponin, Cath lab
LFTs
Medication Hx

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11
Q

Investigations for renal AKI

A

eGFR
inflammatory markers
FBC, blood film
Medication Hx
Renal USS
Renal biopsy

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12
Q

Investigations for post-renal AKI

A

HPC
PMHx
Bladder scan (?retention)
Renal tract USSS, CT KUB, Urethrography
PR exam, PSA

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13
Q

Management for pre-renal AKI

A

SEPSIS 6 (give 3, take 3)
Fluid replacement (crystalloid, colloid)
Abx
Antiemetics
TXA

stop nephrotoxic Mx
- NSAIDS
- aminoglycosides
- ACE inhibitors
- Angiotensin II receptor antagonists
- Diuretics

+lithium, digoxin, warfarin - risk of toxicity

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14
Q

SEPSIS 6 stands for?

A

Give 3:
- antibiotics
- O2
- Fluid

Take 3:
- lactate
- urine output
- blood cultures

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15
Q

management of post-renal AKI

A

NSAIDS (diclofenac PR)
Refer to surgeons

Refer to oncology
Refer to urology

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16
Q

Fluid balance + AKI (HYPOVOLAEMIA)

A

Monitor - Catheter, hourly urine output, NEWS score

HYPOVOLAEMIA - hypotension, capillary refill >2secs, reduced urine output, tachycardia, looks dry

Bolus 250-500ml STAT
Assess after each bolus

Fluid resuscitation >2L required SEEK EXPERT HELP

17
Q

Fluid balance + AKI (HYPERVOLAEMIA)

A

Hypertension, peripheral oedema, raised JVP, lung creps - pulmonary oedema

  • Fluid resus
  • Diuretics
  • Renal replacement therapy
18
Q

Which fluid to give?

A

0.9% normal saline
- contains Cl-, can cause hypercholraemic acidosis
- Consider patients acid-base balance

Hartmann’s
- contains K+
- consider patients K+ level (3.5-5.0)

Blood product if haemorrhage, Hb <70g/l

19
Q

Acidosis + AKI

A

Do a VENOUS BLOOD GAS
- gives bedside acid-base status, Hb, K+, glucose, lactate etc
- can be taken with other bloods + IV access

pH <7.35 = acidosis

AKI typically will cause metabolic acidosis. there may be a respiratory compensation - hyperventilation to “blow off” CO2 (which is acidic)

98% of K+ is intracellular
acidosis causes K+ to shift OUTSIDE OF CELLS = HYPERKALAEMIA

20
Q

Hyperkalaemia + AKI

A

> 5.0 mmol/L

Muscle weakness
Urine - oliguria
Respiratory distress
Decreased cardiac contractility
ECG changes
Reflexes

“murder”

21
Q

ECG changes with hyperkalaemia

A

Tall tented T waves
Small P waves
Wide QRS complexes

can progress to Ventricular Fibrillation/ death

22
Q

Treatment of Hyperkalaemia?

A

TREAT CAUSE

If K+ >6.5mmol/L or ECG changes are present:

  • Calcium Gluconate/Chloride (stabalises cardiac membranes) MOST COMMONLY USED
  • Insulin + Dextrose IV
  • Nebulised SABA (salbutamol) - pushes K+ into cells
23
Q

When to consider Renal Replacement Therapy in AKI?

A

AEIOU

Acidosis (if severe, unresponsive, pH<7.0)

Electrolyte imbalance (severe, unresponsive hyperkalaemia >6.5mmol/L, hypernatraemia >355mmol/L, or hyponatraemia <120mmol/L)

Intoxication (overdose of certain medications)

Oedema (severe, unresponsive pulmonary oedema)

Uraemia (severe >30mmol/L, symptomatic (seizures, reduced consciousness)

24
Q

What is the definition of reduced urine output?

A

<0.5ml/kg/hr

25
Q

Calculate the minimum daily urine output for a patient who weighs 60kg?

A

60 x 0.5 = 30mls/hour

30x24 = 720mls/day

26
Q

Give 3 types of renal replacement therapy?

A

haemodialysis, Peritoneal dialysis, renal transplant

Renal + Urology (15 decks)

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