Critical Care Medicine-Neurologic Disorders>>>>>Vascular Disorders
Question 5#

A 59-year-old female with a past medical history of hypertension, chronic kidney disease, and heart failure with preserved ejection fraction underwent repair of AAA.

Which of the following interventions and goals is MOST likely to reduce her risk of postoperative acute kidney injury?

a. Furosemide to maintain urine output >/= 0.5 mL/kg/hr
b. Bicarbonate containing IV fluid to maintain pH >7.3
c. Volume expansion to maintain CI >2.0
d. Mannitol 0.5 g/kg before aortic cross clamp

Correct Answer is C

Comment:

Correct Answer: C

Postoperative acute kidney injury is a common complication following aortic surgery, which increases hospital length of stay and is associated with significant increases in morbidity and mortality. The incidence varies widely, 18% to 47%, with endovascular repair being associated with a lower incidence as compared to that of an open repair.

The risk factors associated with acute kidney injury after aortic aneurysm repair include pre-existing renal dysfunction, increased age, involvement of the renal arteries in the aneurysm, preoperative exposure to radiocontrast, high complexity, prolonged procedure time, emergency surgery, and perioperative hypotension. These risk factors are related to larger doses of intraoperative contrast, renal microemboli, and inflammatory response. Strategies to prevent kidney injury include adequate perioperative hydration and planning for surgery at least several days from prior contrast administration if feasible. Intravascular ultrasound use intraoperatively can also reduce the dose of contrast needed. 

Various strategies of perioperative renal protection have been proposed including: diuretics; furosemide and mannitol (A, D); calcium channel blockers; N acetylcysteine; bicarbonate; angiotensin-converting enzyme inhibitors; and renal vasodilators, fenoldopam, and dopamine. A 2013 Cochrane review did not support any of these pharmacologic interventions. However, a meta-analysis of studies conducted investigating volume expansion alone or in combination with an inotrope to maintain a cardiac index in the normal range (>2.0 L/min/m2 ) (C) did show a reduction in postoperative acute kidney injury

Both the Cochrane review and meta-analysis caution that many of the included studies are subject to small sample size and possible biases that make interpretation of the results challenging. More evidence is needed to support pharmacologic interventions for perioperative renal protection. Currently available literature support individualized hemodynamic optimization utilizing fluids and inotropes as needed to maintain a cardiac index within the normal range.

References:

  1. Brienza Ni, Giglio MT, Marucci M, Fiore T. Does perioperative hemodynamic optimization protect renal function in surgical patients? A meta-analytic study. Crit Care Med. 2009;37(6):2079-2090.
  2. Canet E, Bellomo R. Perioperative renal protection. Curr Opin Crit Care. 2018;24:1. doi:10.1097/mcc.0000000000000560.
  3. Zacharias M, Mugawar M, Herbison GP, et al. Interventions for protecting renal function in the perioperative period. Cochrane Database Syst Rev. 2013;9:CD003590. doi:10.1002/14651858.cd003590.pub4.