Acute Kidney Injury (& Hyperkalaemia)...

Whilst revising this I couldn't stop myself seeing how easy it is to turn into a part B question, the stem could begin with an ecg and ask you to describe the changes and give the diagnosis. Then ask you to list causes and describe the treatments. Alternatively you could be given a blood gas result including a sodium, potassium and glucose with an Addissonian picture and be asked to list what changes you would look for on the ECG, then to describe your management. Worst case scenario could even be to define an Acute Kidney Injury. Given it lends itself so well it is little wonder that it is a previous part B question!

Acute Kidney Injury:

Definition:

Stage 1: 
- creatinine rise >26 from baseline over 48 hrs
- creatinine rise x1.5 from baseline over 1 week
- Urine output <0.5 ml/kg/hr for 6 hrs

Stage 2:
- creat 2-3x baseline
- urine output <0.5ml/kg/hr for 12 hrs

Stage 3:
- creat >3x baseline
- <0.3ml/kg/hr for 24 hrs or anuria

The Causes are summarised in the following diagram borrowed from the wonderful Sketchy medicine

Investigation in the ED can help pin down the cause: protein on urine dip suggests glomerular disease, blood on dip think TINS (Trauma/ infection/ neoplasm/ Stones). However by far the commonest cause is pre-renal ie poor perfusion (sepsis/ hypovolaemia/ etc).

Management in the ED involves: catheter and hourly urine output, IVI bolus and response monitoring, treat the cause!

Hyperkalaemia

The most significant complication of AKI from an ED perspective is the potential for an increased serum potassium, as this can by imminently life threatening!

• Mild: 5.5-6 mmol/l
• Moderate 6.1-6.9 mmol/l
• Severe >7 mmol/l

See raised K+ think ECG:

• Tall t-waves (easy)
• short QT
• prolonged PR
• wide QRS
• flat p waves
• VT  (may be pulsed)

Treatment:

1. Calcium Chloride 10mls 10% IV - cardioprotective
2. Insulin - shifts potassium intracellular (remember to give with glucose!)
3. Salbutamol neb.

Clever Marks:

Marks may be available for recognising an addisonian crisis (hyponatraemia, hyperkalaemia and hypoglycaemia) and treatments including hydrocortisone.