Ch. 39 Postop Decreased Urine Output Flashcards

1
Q

Is it common to have oliguria following major surgery? If so, why?

A

Yes. This is the result of the response of the adrenal cortex and posterior pituitary to stress from surgery –> fluid loss and shifts

Aldosterone and ADH released in first 24 hrs after surgery are primarily responsible for both salt and water retention

Oliguria > 24 hrs warrants investigation

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2
Q

What imaging is useful in the work-up of oliguria?

A

U/S of the bladder, ureters, kidneys = useful to assess for obstructive pathology

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3
Q

What is a fluid challenge?

A

Give oliguric pt a bolus of NS (500 mL to 1 L) over a short amount of time (typically 30 min) in an effort to increase urine output

With a Foley in place, urine output is recorded hourly. For pts with prerenal AKI due to hypovolemia, with no other injuries to the kidney, urine output should increase

If repeat fluid challenges do not result in improvement in urine output, the possibilities are that the pt remains hypovolemic and needs additional fluid OR oliguria is NOT due to hypovemia. –> Insert central line to measure CVP (normal is 8-12)… values below indicate that you need to give more fluids

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4
Q

What are the indications for urgent/emergent dialysis?

A

If pt remains anuric and renal failure persists, hemodialysis may be performed.

  • Acidosis
  • Electrolyte imbalance (hyperkalemia)
  • Intoxication (ethylene glycol)
  • Overload (fluid)
  • Uremia
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