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Post-Operative Oliguria. Tad Kim, M.D. UF Surgery tad.kim@surgery.ufl.edu (c) 682-3793; (p) 413-3222. Case. 65yo M w PVOD, POD#0 s/p right lower extremity bypass Called by the ICU for UOP 20mL over 2hrs. Initial Assessment. To the bedside, get the nurse/flowsheet Assess ABC
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Post-Operative Oliguria Tad Kim, M.D. UF Surgery tad.kim@surgery.ufl.edu (c) 682-3793; (p) 413-3222
Case • 65yo M w PVOD, POD#0 s/p right lower extremity bypass • Called by the ICU for UOP 20mL over 2hrs
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 -> Resuscitation -> H&P/Labs -> Diagnosis -> Treatment
Resuscitation • Tachycardic, oliguric => hypovolemic • Get 2 large bore IV’s, 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
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
Differential Diagnosis, cont. • Intrinsic renal • ATN (contrast, prolonged pre-renal, toxins, rhabdomyolysis) • AIN (drugs i.e. antibiotics) • Less common in surgical population: • Vascular (Wegener’s, HUS, TTP, embolism) • Glomerular • Nephritic (red cells, red cell casts) • Nephrotic (proteinuria, edema, HTN)
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)
Labs/Imaging • Single most important lab value: FeNa • Send urine & serum for Sodium & Creatinine • Pre-renal: UNa<20, FeNa<1%, BUN/Cr >20 • ATN: UNa>40, FeNa>2% • CBC if suspect bleeding • More complete work-up of ARF: • BMP, UA, Urine eos, CPK, Urine myoglobin, Renal U/S, Complement (lower in SLE)
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
Indications for Hemodialysis • Acidosis (pH < 7.10) • Electrolytes (Hyperkalemia) • Ingestion (Dialyzable toxin overdose) • Overload (Refractory fluid overload) • Uremia • Manifestations of uremia i.e. platelet dysfunction, pericarditis, unexplained AMS
Take Home PointsWhat to do when you’re called with low UOP • “I’m 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