Acute Kidney Injury Flashcards
Define Stage 1 AKI
- rise in serum creatinine ≥ 26umol/L within 48 hours
- 1.5 x increase in last 7 days or 6 hours oliguria (<0.5ml/kg/hr urine output)
Who gets AKI?
- elderly
- CDK (eGFR<60)
- cardiac failure
- liver disease
- diabetes
- vascular disease
- potentially nephrotoxic medications (NSAIDs, ACEi,ARBs)
Management of AKI
STOP
S = sepsis (infection) and hypoperfusion (low bp, low CO)
T = toxicity (drugs/contrast)
O = obstruction (anywhere below renal pelvis)
P = parenchymal disease
How to prevent AKI?
Monitor = obs (BP, pulse), fluid in and output, bloods
Maintain circ = hydration, resus, oxygenation
Min renal insults = hospital acquired inf, nephrotoxic meds, iodinated contrast
Manage acute illnesses
How to use fluids to manage AKI?
- assess volume status (bp lying/standing, HR, JVP, capillary refill, conscious level, lactate, weight)
- hypovolaemic give bolus fluids 250-500mls and review and reg. review
- if ≥ 2L given and still hypoperfused -> further circulatory support
- too much fluid = pulmonary oedema, delayed recovery
- if euvolaemic and passing urine = maintenance fluids which are estimated daily output + 500ml
Which fluids to give for AKI
- isotonic containing K+ (5mmol/L) but low risk of hyperkalaemia
- 0.9% saline (can worsen metabolic acidosis if large volumes infused rapidly)
- colloids = high molecular weight starches and can worsen AKI, not used much now
What to monitor in AKI?
- urinary catheter and hourly in/output (for obstruction?)
- U&Es, bone profile, venous bicarb daily whilst creatinine rising
- blood gases and lactate if septic/hypoperfused
- daily weights
- regular fluid assessment
How to investigate AKI?
- urine dip (PCR to quantify if proteins present)
- US scan <24hours for obstruction, <6 if pyonephrosis suspected (infection-> sepsis)
- inflammatory markers, CKs (rhabdomyolysis, LFTs
- if platelets low blood film/LDH/reticulocyte count (anaemia)
- serum protein electrophoresis (screen for myeloma)
- if glomerulonephritis suspected from proteins on dip = HIV, HCV, igG, Hep B surface antigen
- Anti-GBM
- Complement 3 and 4
- Rheumatoid factor
- ANCAs
- ANA/ENA
Supportive treatment from AKI
- sepsis treatment (sepsis 6)
- maintain perfusion (hydration and fluids)
- stop NSAIDs, ACE, ARB, metformin, potassium sparing diuretics, adjust drug doses (may delay recovery)
- min. iodinated contrast (only if scan needed but minimise)
- stop antihypertensives if hypotensive
Managing hyperkalaemia in AKI
- if ECG changes = calcium gluconate to stabilise cardiac membrane
- if serum K>6.5mmol/L or if ECG changes insulin dextrose (good for 4 hours), but monitor for hypoglycaemia
- if acidotic so bicarb <22 mol/L and not overloaded can give bicarbonate to raise pH and reduce potassium levels but only temporary
- ultimately RRT to restore K+ levels
Pulmonary oedema
AKI comp
- CXR = loss of costophrenic angle
- sit up at right angle
- oxygen infusion
- GTN infusion
- furosemide ≥ 80mg bolus then further or infusion 10mg/hr
- resolution needs recovery of renal function or RRT
Acidosis
AKI comp
- ensure acidosis is renal in origin so raised anion gap, gases, not lactic acidosis or ketoacidosis
- sodium bicarb reserved for hyperkalaemia correction
- acidosis correction by renal function recovery
- pH <7.15 = critical care
Indications for haemodialysis
- pulmonary oedema
- hyperkalaemia
- severe uraemia
- severe acidosis
- insufficient urine output
What to do if obstruction?
- urology refer
- radiology for nephrostomy or stenting
What to do if >1 organ failure, unstable, acute HD unavailable
Intense care for continuous venovenous haemofiltration
