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.