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Anyone know where this definition came from?
<500cc=oliguria...anyone know the study?
- Thread starter GlowInTheDark
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It's a definition, so what would have been studied other than physiology? It isn't even universally defined as 500, with some authors choosing 400 and others, 0.5mL/kg/hr.
Physiologically, the minimum urine output in 24hrs, assuming 600mOsm of obligatory solute excretion and maximum 1200mOsm/L of concentrating capacity, is 500mL.
On PubMed, the oldest accessible paper on oliguria reports that solute concentration is maximal at 0.35-0.5mL/hr, which is about 800mL/24hrs.
The RIFLE guideline for AKI states that an output < 0.5mL/kg/hr for more than 6 hours (~800mL/24hrs for 70kg BW) meets criteria for oliguric AKI which generally portends poor outcomes. A more recent paper challenged this definition saying that < 0.3mL/kg/hr (~500mL/24hrs for 70kg BW) was more indicative of poor outcomes.
It's an old and somewhat arbitrary definition, and is only a marker to alert you to be more vigilant of the causes (hypotension, ischemia, obstruction, i.e. indications for intervention) and consequences of renal dysfunction (i.e. indications for dialysis).
Physiologically, the minimum urine output in 24hrs, assuming 600mOsm of obligatory solute excretion and maximum 1200mOsm/L of concentrating capacity, is 500mL.
On PubMed, the oldest accessible paper on oliguria reports that solute concentration is maximal at 0.35-0.5mL/hr, which is about 800mL/24hrs.
The RIFLE guideline for AKI states that an output < 0.5mL/kg/hr for more than 6 hours (~800mL/24hrs for 70kg BW) meets criteria for oliguric AKI which generally portends poor outcomes. A more recent paper challenged this definition saying that < 0.3mL/kg/hr (~500mL/24hrs for 70kg BW) was more indicative of poor outcomes.
It's an old and somewhat arbitrary definition, and is only a marker to alert you to be more vigilant of the causes (hypotension, ischemia, obstruction, i.e. indications for intervention) and consequences of renal dysfunction (i.e. indications for dialysis).
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