ESRD Guidelines for Aortic Surgery

ESRD Guidelines for Aortic Surgery

Andrew Schober, Anne Donovan, Michael Bokoch

Updated : 5/2023

Patients with severe CKD or ESRD requiring open aortic surgery and aortic cross-clamping pose a particular management challenge to the vascular anesthesiologist. Both impaired renal clearance and the physiologic alterations associated with aortic cross-clamping (metabolic acidosis and electrolyte abnormalities) may create life-threatening metabolic derangements that can be difficult to correct. In addition, pre-existing metabolic derangements (hyperkalemia, renal tubular acidosis, volume overload), if not corrected pre-operatively, can further complicate management as many of these are expected to worsen during cross-clamping and unclamping of the aorta.

Due the complexity of these patients, the anesthetic plan should be tailored to the unique challenges of each patient. However, the following are some considerations when approaching patients with significant renal impairment who present for aortic surgery.

Cross-clamping & Unclamping Physiology

• Metabolic & respiratory acidosis : release of CO2, lactic acid, unmeasured anions from malperfused tissue beds distal to the aortic clamp
• Hyperkalemia : may result from K+ shifting from the intracellular space due to acidosis as well as transfusion, in particular, of unwashed and older units of PRBCs
• AKI, reduced RBF/GFR, decreased UOP : altered RBF and, as a result, impaired GFR result from cross-clamping of the aorta at all levels (including infrarenal); worse with suprarenal clamps and increased duration of clamping; may be worsened further by hemorrhage and hypovolemia

Preoperative Preparation

1. Full dialysis session, low or zero K+ bath (as opposed to the standard 2-4 mEq K+ bath) if difficulty clearing potassium (whether this is possible will depend on the urgency of the procedure but should certainly be completed prior to scheduled surgery). May be worth communicating directly with nephrology to discuss this.

2. Post-dialysis labs confirming clearance of potassium (K+ < 5 at a minimum) and improvement in acidosis

3. Order insulin (1 unit/mL in 100 mL bag): use INTRAOP order set ; have in the room prior to incision along with Dextrose (D50 preferred to limit volume)

4. Decide whether to access dialysis catheter and/or place additional central venous access

a. Best use of the HD catheter is as a volume line or for intraop CRRT
b. Need for additional access may depend on whether HD catheter has an additional infusion port (i.e., Trialysis vs. tunneled dialysis catheter)
c. Consider placing a double- or triple-lumen CVC in addition to the HD catheter for infusions, bolusing of vasopressors, CVP monitoring (may also help ICU when additional access may be needed when the HD catheter is being used for CRRT)
d. Discuss need for additional small-bore CVC with surgeons as they may be concerned about central vein stenosis/long-term dialysis access.

5. Planning of arterial & venous access based on pre-existing dialysis access / AVFs

a. Avoid arterial line placement either proximal or distal to current / working AVF sites due to the risk of compromising the AVF and the potential for inaccurate blood pressure measurement.
b. Avoid arterial line placement distal to prior AVF sites unless no other option due to questionable correlation with central arterial pressures.
c. Consider brachial or axillary arterial line sites above failed AVFs if more distal sites are compromised.
d. If the wire is not passing during CVC placement, maintain a high index of suspicion for central venous stenosis from prior HD catheter access and consider an alternate site

Intraoperative Interventions

1. Wash PRBC units : takes time; discuss with Cell-Saver technician early in the case, in particular if large EBL is expected. If Cell-Saver is not planned for the case (due to infection, tumor, etc.), request that the surgeons rebook the case with Cell-Saver  in order to wash blood and assist with loading / running the Belmont / rapid infuser.

NOTE : It doesn’t take much time (5-10 min) to wash a unit once they are set up.  But if you are going to need blood, which you will, wash early and have 2-4 units of washed blood in the Belmont, ready to go, at all times. It is easier for them to “stay ahead” washing blood than to “catch-up.”

2. If Cell-Saver is unable/unavailable to wash banked pRBC units, communicate directly with Blood Bank to obtain fresh (< 14 day old) pRBCs.

3. Attempt to normalize K+ prior to cross-clamp : if K+ is high (> 4.5) or trending in the wrong direction, consider starting insulin/dextrose gtt’s early to maximize trans-cellular shift (reasonable starting dose : insulin 5U/hr + D50 5mL/hr).

4. If patient produces urine, consider an early dose of furosemide 40-80 mg IV (Lasix) and chlorothiazide 500 mg IV (Diuril) to maximize K+ excretion, +/- furosemide infusion at 10-20 mg/hr

5. Discuss potentially delaying cross clamp, if necessary, in order to correct metabolic derangements as these are expected to worsen once the cross clamp is applied.

6. Aggressively treat metabolic acidosis and attempt to compensate with hyperventilation to induce a respiratory alkalosis during cross-clamp given the lack of renal compensation for electrolyte derangements. Hyperventilation and a compensatory respiratory alkalosis are particularly important prior to unclamping to further shift K+ intracellular and in anticipation of acute worsening of the metabolic acidosis upon unclamping.

7. Consider prophylactic bicarbonate IV bolus if K+ is elevated prior to aortic unclamping.

8. May consider low dose epinephrine infusion 0.02 mcg/kg/min. Better than albuterol at shifting K+ if the HR/ischemia is not limiting.

9. Intraop CRRT : needs to be setup in advance, requires an ICU nurse to run the machine ; limited ability to quickly correct fluid and electrolyte shifts ; in general, not very practical due to the complexities of mobilizing all the resources needed.

10. Certain interventions, including Kayexelate / Lokelma and diuretics, have limited effect in the short term and when there is pre-existing renal dysfunction

Postoperative Considerations

1. Assess state of metabolic derangements in the post-unclamping period (electrolyte derangements, clearance of metabolic acidosis), in particular the trend (improving or worsening).

2. Consider whether patient is likely to need CRRT or iHD in the immediate postop period.

a. CRRT : more hemodynamically stable; easier to control ongoing fluid shifts and volume status going forward; slow to clear electrolyte derangements due to low flow.
b. iHD : better at quickly resolving electrolyte derangements (hyper K+) ; short duration of therapy may be inadequate to manage volume status in the acute setting ; hemodynamics may not tolerate immediately postop due to high flows and volume shifts

3. Consider placing dialysis access in the OR as there may be substantial delays after arrival in the ICU due to the need for ongoing resuscitation and stabilization. CRRT cannot be done through an AV fistula due to the risk of fistula clotting at low flows. If CRRT is needed in a patient with ESRD and a pre-existing AVF, placement of an HD catheter / Trialysis line IS necessary.

4. If CRRT is needed urgently postop or intraop, contact the ICU (triage fellow, 10ICU charge, 10ICU front desk,  or patient’s postop destination unit) and/or consult nephrology directly to initiate the process of starting RRT in order to avoid delays.

a. ICU triage: 415-353-9209
b. 10ICU charge nurse: 415-353-4525
c. 10ICU, unit number: 415-353-1007
d. Nephrology (Parnassus): use pagerbox “Parnassus Nephrology New Consults Only”; 415-443-4744 (pager)