PostOperative Oliguria

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Post-Operative Oliguria

• Tad Kim, M.D.
• UF Surgery
• tad.kim_at_surgery.ufl.edu
• (c) 682-3793 (p) 413-3222

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Case

• 65yo M w PVOD, POD0 s/p right lower extremity
  bypass
• Called by the ICU for UOP 20mL over 2hrs

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Initial Assessment

• To the bedside, get the nurse/flowsheet
• Assess ABC
• Airway patent, breathing/conversant
• VS Afebrile, P 105, BP 99/60, Sats 96 RA
• For any situation
• ABC -gt Resuscitation -gt HP/Labs -gt Diagnosis -gt
  Treatment

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Resuscitation

• Tachycardic, oliguric gt hypovolemic
• Get 2 large bore IVs, place Foley continuous
  monitoring
• Fluid Bolus
• 20mL/kg (infant) or 1L (adult) of isotonic
• NS, LR, or Plasmalyte
• Repeat if still dehydrated clinically
• Once pt is resuscitated, move onto Dx

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Differential Diagnosis

• Pre-renal (2ndary to ? renal perfusion)
• Dehydration, bleeding
• Shock 2ndary to sepsis, cardiogenic, CHF, PE
• Abdominal compartment syndrome
• Post-renal (obstructive)
• Stones
• Extrinsic compression on ureter, bladder, urethra
  (BPH, CA)
• Obstructed Foley catheter

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Differential Diagnosis, cont.

• Intrinsic renal
• ATN (contrast, prolonged pre-renal, toxins,
  rhabdomyolysis)
• AIN (drugs i.e. antibiotics)
• Less common in surgical population
• Vascular (Wegeners, HUS, TTP, embolism)
• Glomerular
• Nephritic (red cells, red cell casts)
• Nephrotic (proteinuria, edema, HTN)

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History and Physical

• History (straightforward)
• Ask for h/o contrast administered, anesthetic,
  nephrotoxic agents, antibiotics
• Physical
• Fever (sepsis)
• Signs of dehydration
• Signs of bleeding
• Tip Flush the Foley (catheter obstruction)

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Labs/Imaging

• Single most important lab value FeNa
• Send urine serum for Sodium Creatinine
• Pre-renal UNalt20, FeNalt1, BUN/Cr gt20
• ATN UNagt40, FeNagt2
• CBC if suspect bleeding
• More complete work-up of ARF
• BMP, UA, Urine eos, CPK, Urine myoglobin, Renal
  U/S, Complement (lower in SLE)

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Treatment

• Pre-renal give volume (or blood)
• Assess for CHF/HTN/edema (sign of overload)
• Sepsis Volume broad-spectrum Abx
• Contrast-induced nephropathy
• Volume, N-acetylcysteine, (?)bicarbonate
• Rhabdomyolysis
• Volume, Alkalinize the urine
• Nephrotoxin or AIN stop the agent
• Consider saline to flush kidneys, ? toxicity

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Indications for Hemodialysis

• Acidosis (pH lt 7.10)
• Electrolytes (Hyperkalemia)
• Ingestion (Dialyzable toxin overdose)
• Overload (Refractory fluid overload)
• Uremia
• Manifestations of uremia i.e. platelet
  dysfunction, pericarditis, unexplained AMS

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Take Home PointsWhat to do when youre called
with low UOP

• Im on the way. Flush the Foley, draw BMP, UA,
  Urine sodium, Urine creatinine
• Assess ABC, Resuscitate if hypovolemic
• Unless pt has CHF, safe to start w fluid
  challenge
• Once resuscitated, work through is this
  pre-renal, post-renal, or intrinsic?
• Pre dehydrated, septic, bleeding, shock
• Post stone, obstructed Foley, cancer, BPH
• Intrinsic contrast, drugs, rhabdo
• FeNa is the key to determining pre vs ATN
• Complete the work-up treat underlying prob