AKI + Urinary retention

Question 1

Definition of AKI

Answer 1

• 50% or more increase in creatinine from baseline over last 7 days
• Increase in creatinine by 26.5umol/L or more within 48hrs
• Urine output less than 0.5mls/kg/hr for more than 6 hrs

Question 2

Staging AKI

Answer 2

Creatinine levels
* Stage 1 - 1.5-1.9x baseline
* Stage 2 - 2-2.9x baseline
* Stage 3 - 3x baseline

Question 3

Example of one cause of pre-renal, intrinsic renal and post renal AKI

Answer 3

• Pre-renal - hypovolaemia eg haemorrhage/dehydration
• Intrinsic - gentamicin
• Post renal - bilateral ureteric stones, BPH

Question 4

Investigations for AKI - bedside and bloods

Answer 4

• Assess fluid status
• Bladder scan - retention?
• Review drug chart - nephrotoxic meds?
• Urine dip
• Bloods - U&E, FBC, CRP, LFT, Ca2+
• Blood gas if acid/base imbalance suspected

Question 5

How does urine dip help differentiate causes of AKI

Answer 5

• Can differentiate between pre-renal and intrinsic renal AKI
• Pre-renal AKI - urine specific gravity and urine osmolarity will be higher, Na+ excretion lower - kidney conserves water compared to intrinsic causes
• Any GN cause will show high levels of blood and protein

Question 6

Imaging for suspected AKI

Answer 6

• USS KUB - if severe and no response to initial management to check for obstruction
• If hydronephrosis - obstructive cause?

Question 7

Management AKI

Answer 7

• Assess fluid status
• Pre renal AKI - fluid bolus 250-500ml over 15 mins
• Reasses after 10-15 mins
• Monitor urine output
• Repeat boluses until euvolaemic - then maintenance fluids if needed

Question 8

Ongoing monitoring for AKI

Answer 8

• Monitor urine output - fluid balance chart, consider catheter
• Regular bloods - U&Es
• If not responsive to initial fluid therapy - consider intrinsic/post-renal cause

Question 9

Drugs to be potentially stopped in AKI

Answer 9

• ACEi/ARBs
• NSAIDs
• Aminoglycoside abx
• Potassium sparing diuretics - risk of high K+

Take A NAP with AKI

Question 10

Drugs to be altered/reduced in AKI

Answer 10

• Metformin - risk of lactic acidosis
• Diuretics - if intravascular deplete
• LMWH

Question 11

Symptoms of acute urinary retention

Answer 11

• Little/no urine passed
• A sensation of needing to void - without being able to (can be painless if previous chronic retention though)
• Suprapubic mass that is dull to percussion

Question 12

Common causes of acute urinary retention post op

Answer 12

• Uncontrolled pain
• Constipation
• Infection
• Anaesthetic agents (eg spinal/epidural use) - consider neurological problem but can just be not worn off yet

Question 13

RF for acute urinary retention post op

Answer 13

• Age over 50
• Male
• Previous retention
• Type of surgery - pelvic or urological
• Neurological or urological co-morbids
• Medications - antimuscarinics, alpha agonists, opiates

Question 14

Bedside investigations for suspected urinary retention

Answer 14

• USS bladder scan - identify post void residual volume
• U&E - check kidney function - if worsening could suggest high pressure retention

Question 15

Management acute urinary retention

Answer 15

• Conservative - will resolve usually if given time and withdrawal of causative agent
• If do not resolve - catheterisation then TWOC shortly after

Question 16

What if the patients fail the TWOC?

Answer 16

• New catheter
• Repeat TWOC in 1-2 weeks in community
• Re-assess for any reversible causes and why the patient failed their TWOC