Management of Acute Renal Failure
General Supportive Measures. Patients with ARF should
be closely monitored. The cause of the ARF should be
identified by looking at prerenal, renal, and postrenal
causes. Laboratory evaluations should include serum and
urine electrolytes, urinalysis, and examination of urinary
sediment. Careful assessment of volume status is necessary
to determine hypovolemia, leading to prerenal azotemia
versus hypervolemia from oliguria. Correction of
acid-base disturbances may be necessary, as well as correction
of electrolyte abnormalities. Continuous renal
support is often required in patients with advanced renal
failure to help with volume overload and electrolyte disturbances.
Antibiotics and other medications should be
dosed according to creatinine clearance, and serum levels,
if available, should be closely monitored. Platelet dysfunction
may occur as a result of uremia and require desmopressin
(DDAVP) for support if bleeding is problematic.
Resuscitation fluids with high chloride concentration
(0.9% saline, 4% to 5% albumin) are associated with
decreased urine flow and electrolyte secretion, hyperchloremic
metabolic acidosis, and renal vasoconstriction.
A recent open-label, sequential study where high chloride-
containing solutions were restricted in critically ill
patients showed decreased progression to renal failure and
a reduction in the need for renal replacement therapy.151
Renal Support. ARF in the ICU often requires some
type of renal replacement therapy. Commonly, this is
accomplished by continuous venovenous hemofiltration
(CVVH), a form of CRRT. Although CRRT has several theoretic
advantages over intermittent hemodialysis (IHD),
such as enhanced hemodynamic stability, increased
solute removal, and greater ultrafiltration capacity,
individual randomized trials have not supported its superiority.
152,153 The timing and dosing of this therapy and
the patients most likely to benefit from it remain unclear.
Recently, it appears that the difference in efficacy lies
not in the type of dialysis (IHD versus CVVH) but in the
dialysis dose. Undertreatment appears to be harmful,154
whereas earlier application and higher filtration volumes
appear to be associated with decreased mortality in
patients with ARF.155 On the other hand, intensive-dose
CRRT has also not been shown to be beneficial in terms
.of mortality, renal function recovery, and ICU LOS.156-158
Even with IHD, which can cause more hemodynamic lability,
when studies are controlled for dialysis dose, polymer
membrane, and bicarbonate-based buffer, 60-day mortality
did not differ between the two groups (CRRT versus
IHD).159 Although a trend to use CRRT has developed,
favorable data with IHD are intriguing because using IHD
would allow more ICU resources to be allocated elsewhere.