Acute Kidney Injury Part 1:
Approach to the patient with AKI
The combination of shock and AKI has a high mortality necessitating appropriate timely intervention.
1. Stabilise the patient whilst trying to improve or protect renal function by identifying potentially reversible factors
2. Seek underlying cause of AKI
3. Commence renal replacement therapy when appropriate
- Immediate concerns are hypoxaemia, blood volume abnormalities (hypovolaemia or fluid overload), hyperkalaemia and metabolic acidosis.
- Correct hypoxaemia with high concentration oxygen. If pulmonary oedema is a major issue CPAP or intubation and ventilation may be necessary until fluid can be removed with renal replacement therapy. Uraemia can result in ARDS (especially in the presence of sepsis) so simply removing fluid may not lead to acute resolution of pulmonary oedema and hypoxaemia.
- IV access. Remember sites in upper limbs may subsequently be required for fistulae and consider using only one arm for cannulae and blood sampling (remembering potential pitfalls of blood dilution).
- Recognise and treat hyperkalaemia (see later).
- Correct volume status. If shocked commence resuscitation: see shock tutorial. Nb high mortality in this group.
- Insert a urinary catheter and measure hourly volumes.
- Invasive haemodynamic monitoring (arterial line and central venous catheter) will help guide volume replacement and vaso-active drug therapy.
IMPORTANT: insertion of internal jugular or sub-clavian CVCs in the hyperkalaemic patient risks the guidewire touching the endocardium and inducing life threatening and refractory arrhythmias. Femoral venous cannulation avoids this risk and is usually achievable quickly. If inserting an internal jugular line it is ideal to use the left internal jugular for the central venous catheter preserving the right internal jugular for the haemofiltration line which generally performs better on the right.
- Do not give loop diuretics unless there is a positive reason (such as pulmonary oedema or hyperkalaemia).
- Stop nephrotoxins including drugs which may be a factor in AKI and hyperkalaemia.
- Treat metabolic acidosis: discuss with senior medical staff.
- If hyperkalaemia requires urgent renal replacement therapy (haemodialysis/haemofiltration) the first treatment should be performed locally.