SAMIR EL ANSARY

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

-Reduced cardiac output examples: CHF; cardiac temponade; constrictive pericarditis.-Drugs that may decrease renal perfusion: Diuretics, ACE, NSAIDS, immunosuppressive (cyclosporine)-Why consider liver function? Hepatorenal syndrome-ATN: hypotension; nephrotoxins (contrast, myoglobin, uric acid, amyloid …etc)-AIN: drugs (antibiotics, NSAIDS, diuretics), infection

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

-Vitals: orthostatics can signify hypovolemia; Tachycardia - hypovolemia/infection; Fever – infection/UTI-Jaundice (liver cirrhosis – hepatorenal)-Crackles, pleural effusion (CHF, volume overload)-JVP, CVP if pt has central line (will help assess fluid status)-Palpate Kidneys and Bladder (hydronephrosis, enlargement in obstruction/post-renal)-Prostate/Cervical Exam (again for obstruction/post-renal)-Rash (AIN, embolic renal failure)

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

-Urine studies: U/A – look for proteinuria, hematuria, eosinophilia, evidence of rhabdomyolysis, RBC/WBC/Granular/Pigmented/epithelial casts…etc. -Urine lytes: e.g. urine sodium <20 (prerenal), FENa: <1? Vs >2%/ FeUrea: <35?-Note: On CMP look for presence and degree of renal insufficiency. Also look for possible complications (especially one that can be life threatening) of renal insufficiency (e.g. hyperkalemia, metabolic acidosis…etc).

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 f luid 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.

GOOD LUCK

SAMIR EL ANSARY