Episode 264: TAAA Repair with Dr. Mimi Wynn

Anesthesia and Critical Care Reviews and Commentary (ACCRAC) Podcast
Anesthesia and Critical Care Reviews and Commentary (ACCRAC) Podcast
Episode 264: TAAA Repair with Dr. Mimi Wynn

In this 264th episode I welcome Dr. Mimi Wynn to the show to discuss anesthesia for TAAA repair. We discuss preoperative concerns, intraoperative management, postoperative concerns especially spinal cord ischemia, and how to reduce the risk of that dreaded complication.

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4 thoughts on “Episode 264: TAAA Repair with Dr. Mimi Wynn”

  1. Wonderful episode!

    Perhaps Dr. Wynn could weigh in on the following:

    The role of intraop neuromonitoring to prevent spinal cord injury?

    In the event of post op neurological deficit, balancing the goals of increased MAP to augment spinal cord perfusion vs protecting fresh arterial anastamosis?

    1. Changes in motor evoked potentials, of course, can detect spinal cord ischemia. Intraoperative MEP monitoring has been used to identify segmental arteries to re-implant (Jacobs 2006) or ligate (Etz & Griepp 2006). Both clinical studies found that ischemic changes were reversed simply by increasing MAP. Although there is theoretical reason to monitor MEPs intraoperatively, we have found MEPs to be impractically slow during complex TAAA repair and unreliable during hypothermia. Since we know increasing the MAP reverses ischemic changes we focus on MAP and spinal fluid pressure to maintain adequate perfusion pressure in the spinal cord collateral network and other neuroprotective strategies. We do not use assisted circulation in TAAA repair. One benefit of clamp and sew technique is the MAP is high. MEP monitoring may be more useful when assisted circulation is used because MAP during partial bypass is lower. If surgeons are concerned about bleeding with higher MAP, MEPs may be used to determine MAP at which ischemia occurs in an individual patient. Although postoperative MEPs can be used to identify that same threshold, MEP monitoring in the ICU is labor intensive and requires skilled interpretation.
      Management of TAAA patients is complex. They have long standing hypertension. Many have LVH and CAD and require higher renal and coronary perfusion pressure after surgery. Return to near baseline MAP is usually desirable. To have excellent outcomes in TAAA surgery, surgeons must sew hemostatic anastomoses and anesthesiologists must proactively manage large intraoperative blood loss (during hypothermia) to prevent coagulopathy. If these goals are met, there is less need to lower the blood pressure postoperatively to protect arterial anastomoses.

  2. Extremely educational, thank you so much Dr. Wynn and Dr Wolpaw for putting this show together.

    I have a question regarding, transfusing blood product in this type of case. As mentioned on the show, the blood loss during such a case can be very large during a very short period of time (ei aorta is extremely calcific and cannot be clamped when desired, etc). At our institution, we use blood salvage which is able to capture the majority of the blood lost, however, could not be processed fast enough before the patient is rendered in extremis and blood bank blood has to be administered. After some blood bank blood is administered, cell salvage blood becomes available but only part of it is needed before the patient became volume replete.

    What is the best strategy to deal with the remainder of the cell salvage blood? Discard? or administer to the patient since it’s their own blood, with concomitant Nitro gtt, to allow the venous reservoirs to enlarge to hold the extra blood volume until body equilibrates?

    Any chance Dr. Wynn would be willing to share the protocol or checklist she uses for these cases, I found myself getting a bit confused on which strategies were for open vs endovascular, perhaps it would be more clear on a list.

    Thank you again so very much!

    1. From Dr. Wynn:

      Other than keeping goal-directed therapy in mind, there’s no right answer. We replace acute surgical blood loss with blood components when the aorta is open, knowing at least one blood volume will be lost during this short time. We administer blood components as indicated by blood loss, blood pressure, Hb, and clotting parameters. If we resuscitate adequately with banked blood during surgical hemorrhage, we delay replacing cell saver blood. We replace insensible deficit with crystalloid only after surgical bleeding is controlled. For TAAA surgeries, our technicians place cell saver blood in blood salvage bags. Because cell saver blood can be saved up to 6 hours at room temperature, it is possible to use it when hemodynamics change after reperfusion and later in surgery when crystalloid replacement of insensible losses causes hemodilution. It would be unusual for us not to use all the cell saver blood, but if it is not needed, we discard it. We do not increase capacitance to make room for cell saver blood that is not needed to meet goal Hb.

      We’ll try get the checklists posted in the show notes.

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