How do I manage an oliguric patient in ICU?

Regardless of the strategy employed, the prevention of renal failure by appropriate resuscitation and hemodynamic manipulation has a big impact in improving outcome in multiorgan failure syndrome (MODS). In critically ill patients who develop renal failure the mortality rate increases from 10% to greater than 60%.

A management strategy for oliguria

1.  The first thing to do is simple: out rule a post-renal cause: flush or change the urinary catheter. If the patient’s abdomen is tense and distended, treat them as pre-renal (below) and transduce the bladder pressure, looking for evidence of intra-abdominal hypertension.

2.   In most cases oliguria is prerenal. Perioperative oliguria should be assumed to be due to intravascular hypovolemia until otherwise proven. Examine the patient quickly for evidence of heart failure (similar urinary findings, due to forward failure) – gallop rhythm, bibasal crackles, raised JVP, parasternal heave, hepatomegaly, sacral edema. If the patient is not in heart failure, load them with isotonic fluid (lactated ringers, normal saline or colloid), and follow vital signs – heart rate, blood pressure and urinary output. Do not give diuretics until you are certain that the patient is fully fluid loaded (and still oliguric).

3.  If unresponsive to multiple challenges, evaluate intravascular volume by inserting a CVP line. In the under-resuscitated patient, CVP falls off soon after volume loading, often following a temporary rise.

4.  If the CVP rises and stays high (14-16mmHg) then volume loading is complete (although some physicians would measure true preload with a pulmonary artery catheter at this point). If urinary flow is still poor, and the blood pressure is low or marginal, it is time to try to increase renal perfusion pressure (“squeeze”) with a vasopressor, such as norepinephrine. If cardiac function is poor, a more potent inotrope, such as dobutamine, may be more effective. The use of vasoactive drugs may be particularly useful in vasomotor nephropathy, where autoregulation has failed.

5.   If the patient is fully volume loaded or overloaded, it is time to flush the renal tubules, and use diuretics.

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