Week 2 - AKI Flashcards
What is acute kidney injury?
Recognised by significant elevation of serum creatinine within hours or days or significant decrease in U/O for >6 hours.
What is chronic kidney disease?
When GFR is <60mL/min/1.73m^2 for >3 months with/without evidence of kidney damage.
What is the function of the kidneys (excretory)?
- Remove waste products
- Remove excess fluids
- Regulate acid-base balance
- Regulate electrolyte levels
What is the function of the kidneys (secretory)?
- Regulate BP
- Regulate RBC
- Regulate calcium uptake
What is hyperkalaemia?
A condition in which serum potassium is >5.3mEq/L.
Investigations of hyperkalaemia:
- Assess renal function
- Measure urine K+ and Na+ concentrations and urine osmolarity
- Measure complete blood count
- Complete metabolic profile
What is acidosis?
Occurs when the renal tubules fail to regenerate bicarbonate and secrete H+ ions into the urine.
Describe renal autoregulation.
Controlled by 2 mechanisms
• Myogenic control (BP)
• Via tubuloglomerular feedback system
3 causes of renal failure.
- Pre-renal failure
- Intra-renal failure
- Post-renal failure
What is pre-renal failure?
- Most common
- Hypovolaemia
- Decreased vascular filling
- Heart failure and cardiogenic shock
- Decreased renal perfusion due to vasoactive drugs of diagnostic agents
What is intra-renal failure?
Caused by vascular disorders or acute tubular necrosis.
What is post-renal failure?
Caused by obstruction of the urinary tract such as BPH, kidney stones, urinary catheters and cancer.
What serum values are indicative of renal disease?
Stage 1
<0.5ml/kg/hr for 6-12 hours
1.5-1.9 x baseline
Stage 2
<0.5ml/kg/hr for >12 hours
2-2.9 x baseline
Stage 3
<0.3ml/kg/hr or Anuria >12 hours
3 x baseline
What extra-renal causes may cause these serum values to become elevated?
Raised creatinine and raised urea.
4 phases in the clinical course of acute renal failure:
- Onset
- Oliguric-anuric
- Diuretic
- Recovery
What is the onset phase?
- Represents the time from initial insult to cell injury
- Can last from hours to days
- Renal blood flow and O2 consumption at 25%
What is oliguric-anuric phase?
- Lasts 8-14 days
* Characterised by damage to the tubular wall and basement membranes
What is diuretic phase?
- Appears when the obstruction to tubular flow has passed
- Lasts 7-14 days
- Increase in GFR with
What is recovery phase?
- Stabilisation of lab results and can range from 1-12months
* Oedema subsides and tubular cells return to normal function
What is the significant use of gentamycin and what should you be monitoring for?
- Nephrotoxic
- Excreted exclusive via kidneys and is toxic to proximal tubule
- Serum creatinine and serum urea need to be monitored however takes 2-3 days
- Monitor U/O more stringently
What does peaked T waves indicate?
Hyperkalaemia.
