Download - DECREASED URINE OUTPUT (Oliguria)
Artak LabadzhyanMini-Lecture Powerpoints
1/30/12
Definition of decreased urine output (oliguria)
Questions to consider when first presented with oliguria
Recognizing causes of oliguria Focused review of history and physical Management of oliguria
◦ Recognizing life threatening complications
Oliguria = Urine output <400cc/day (<20cc/hr) ◦ Another def: urine output <0.5ml/kg/hr
Anuria = no urine output◦ Can signify complete mechanical obstruction of
bladder outlet or a blocked Foley
Does the pt have a foley catheter?
YES NO
FLUSH FOLEY CATHETER WITH 30-50CC NS
OBTAIN PVR (w/ US or cath [will provide urine sample])
URINE OUTPUT IMPROVED? PVR ≥ 100? (≥ 50 in younger pts)
YESYES NO NO
FOLEY LIKELY CLOGGED WITH SEDIMENT
PROCEDE WITH FURTHER MANAGEMENT
START FOLEY & PROCEDE W/ FURTHER MANAGEMENT
PROCEED WITH FURTHER MANAGEMENT
Consider the pathophysiology/causes of decreased urine output. Three categories of causes:
Prerenal:◦ Volume depletion/dehydration/inadequate fluid
maintenance/Infection/sepsis◦ Reduced cardiac output
ICU setting: mechanical ventilation can also lead to low cardiac output
◦ Drugs◦ Does the pt have liver cirrhosis
Intrarenal:◦ ATN
ICU settings: Circulator shock, severe sepsis, multiorgan failure
◦ AIN◦ Renal artery thrombosis/Emboli (septic [endocarditis]
Postrenal:◦ B/l ureteric obstruction (stones, clots, tumors, fibrosis)◦ Bladder outlet obstruction (BPH, tumors/retroperitoneal
mass, clots)◦ Foley catheter obstruction
Review chart to look for clues that may elicit etiology (see previous slide)
History (sepsis, CHF, tumors, renal failure…etc)
Meds: diuretics, ace, aminoglycosides/vancomycin, iv contrast, NSAIDs
Old Labs: BUN/Cr (ratio); urine lytes; blood cultures; vanco trough levels
Obtain new vitals, including orthostatics Look for:
◦ Jaundice ◦ Crackles, pleural effusion ◦ JVP, CVP if pt has central line
Especially useful in ICU for pt with central line: for example a CVP of 2 can be good evidence for hypovolemia
◦ Palpate Kidneys and Bladder ◦ Prostate/Cervical Exam ◦ Rash
If not already done, order basic electrolytes, CMP (monitor changes in Cr/GFR), and urine studies (U/A, Na, BUN, Cr), to further help classify etiology
Adjust/replace/discontinue and nephrotoxic agents. Also, renally dose the non-toxic meds
Early recognition and intervention of potential life threatening complications (direct or indirect causes – e.g. renal failure) is essential◦ Hyperkalemia: obtain EKG if elevated◦ CHF/Pulmonary Edema◦ Metabolic acidosis; Uremia (encephalopathy,
pericarditis)◦ Advanced complications of above may require
dialysis
Prerenal:◦ Treat underlying cause◦ If volume depleted (see physical exam): NS boluses
(500-1000ml fluid challenges) – can repeat until response (but need to monitor for fluid overload)
◦ Avoid/be very cautious about giving lasix (again investigation of underlying cause should drive this decision).
Postrenal:◦ Treat underlying cause◦ Initiate Foley catheter (clear/flush catheter if already
in place)◦ Obtain Renal Ultrasound to assess for upper urinary
tract problems Intrarenal:
◦ Treat underlying causes (e.g. sever sepsis/shock)
Verify urine output w/ definition of oliguria in mind. If pt has a Foley catheter, flushing Foley is a good initial
step. If no Foley, a PVR can help assess the need for Foley.
A focused chart review along with a focused history and physical can help clue in on the pathophysiology including pre-renal/intrinsic/post-renal causes.
Recognizing life threatening complications (e.g. hyperkalemia, acidosis, uremia) is an essential component of acute/early management.
Decreased urine output does NOT mean lasix deficiency. Administering lasix may actually exacerbate problem. However very specific causes may require lasix.
Fluid boluse(s) is a good initial step (be very cautious in CHF).
Ultimately, regardless of pathophysiology, treating underlying cause is key for both acute and long term management.