You are here: Handbooks » Unit handbook » Acute renal failure - management

This section covers general management of acute renal failure only. Diagnosis, prevention and specific treatment are not discussed.

Initial actions

Initial management should comprise:

Note that there is no evidence that dopamine is of benefit other than through its action as an inotrope - but inotropes may be valuable in heart disease or shock. There are some reasons to suspect that dopamine may be potentially harmful as it impairs splanchnic perfusion. Loop diuretics may increase urine output in those with less severe degrees of renal failure, but there is no evidence that they improve outcome (requirement for dialysis, or mortality) and some evidence that they can be harmful. Most interventions tested in prevention of ARF after radiographic contrast administration are ineffective or harmful (eg loop diuretics), apart from fluid administration alone: and N-acetylcysteine may at least do no harm (See Radiology).

 

Renal replacement therapy

Indications for dialysis are

Neither age nor comorbid conditions (that might lead you to question longterm RRT) should be considered as automatically disqualifying dialysis for ARF if there is a substantial chance of recovery. BUT:

Peritoneal dialysis is now rarely used for ARF in the UK, though it can be effective if the patient is not too catabolic and ultrafiltration requirements not too extreme.

Continuous or very slow treatments (haemofiltration or haemodialysis)


Intermittent haemodialysis

Patients with ARF need at least as much dialysis, and frequently more (because of catabolism) than patients with ESRF. Therefore Kt/V or URR should be at least as good. Dialysis usually need to be more frequent and daily treatments should be regarded as the norm in the early phase, or if fluid fluxes are substantial (e.g., from feeding).

 Up to top

 

Preventing disequilibration

Disequilibration is a state of clouding of consciousness, confusion and sometimes fits following dialysis. Disequilibration is most likely:

If the risk is significant it is sensible to give a low-clearance (e.g., Kt/V 0.5, or 30% URR) and low intensity (low blood flow and/or small dialyser) treatment initally, intermediate the next day, a full treatment (e.g., Kt/V 1.2, URR 70%) the third day, if figures permit.

A ‘gentle start’ is inappropriate if fast removal of small molecules is required - e.g., in severe hyperkalaemia or for removal of low molecular weight poisons such as salicylate. CVVH is also inappropriate in these cricumstances (unless the toxin is of molecular size better removed by haemofiltration).

First dialysis treatments can and should be less cautious in catabolic patients in whom figures are rising fast.


Haemofiltration

Haemofiltration, whether contiuous or intermittent, is less efficient at removal of small molecules including toxins. Prolonged haemolfiltration commonly leads to phospate depletion, replacement may be required, and it clears some drugs (e.g., vancomycin) faster than haemodialysis.


Amount of dialysis

Detailed calculations of dialysis dose is beyond the scope of this summary, but see the brief description under 'Haemodialysis'. Note that for haemofiltration, Kt is equal to (or for urea, >90% of) the total volume of fluid exchanged. 


Comparisons

For very crude comparison of small molecule clearance by continuous versus intermittent treatments, the following figures are provided. HD figures are for urea clearance by F8 dialyser, ignoring UF.

Modality Urea clearance
Normal GFR 150 l/day
Daily intermittent HF 15-25 l/day
Continuous HF at 1 l/hr 24 l/day
Continuous HF at 2l/hr 48 l/day
Daily HD x 4hr at QB = 200ml/min 46 l/day


Dietary Management

Is important, and is described further in the DIET section.
  

Other Treatment

Patients with acute renal failure should receive H2-blockers or PPls. Prophylaxis against DVT should usually be ued in bed-bound patients.

  Up to top

 

 

(no previous) >> Acute renal failure - 'screen' (tests)