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October 2010 Supplement
Treating Ruptured Abdominal Aortic Aneurysms
Setting up your practice for an endovascular approach.
Endovascular methods have recently led to dramatic reductions in mortality associated with patients presenting with a ruptured abdominal aortic aneurysm (rAAA). In 1991 at our institution, the mortality rate for this aortic catastrophe was 70%.1 A recent analysis of this same population of patients demonstrated a mortality rate of 57.8% for patients undergoing open repair of an rAAA. In 2007, we implemented a protocol for managing rAAA patients with a preference for endovascular aneurysm repair (EVAR) when feasible.2
THE HARBORVIEW EXAMPLE
Harborview Medical Center in Seattle, Washington, is a
level-1 trauma center serving a five-state region representing
25% of the landmass of the United States and
nearly 15 million people. Approximately 30 to 50 rAAAs
are seen and treated annually. In 2007, an endovascular
protocol was established to manage this seriously moribund
patient population in a timely and efficient manner.
Our protocol at Harborview was adopted from that
of the Albany Group (Figure 1).3 During our study period
over 7 years, 187 patients with rAAAs presented to our
institution. Before implementation of the algorithm, 131
patients with rAAAs presented and 128 were treated
with open repair. The 30-day mortality rate was 57.8%.
After implementation of the protocol, 56 patients with
rAAAs were managed. Twenty-seven patients (48%)
underwent successful EVAR, and 24 patients (43%)
underwent open repair. Five patients (9%) underwent
comfort care only. In the postprotocol period, five
patients in the EVAR group (18.5%) and 13 patients in
the open group (54.2%) died during the follow-up period
for an overall 30-day mortality rate of 35.3% (P = .008 vs
57.8% preprotocol). After implementation of a structured
protocol for managing rAAAs, there was a relative
risk reduction in 30-day mortality of 35% compared to
the time before implementation of the protocol (95%
confidence interval [CI], 14%–51%) corresponding to an
absolute risk reduction of 22.5% (95% CI, 6.8%–38.2%). A
review of the most recent 12-month experience with this
protocol at Harborview has revealed a mortality rate of
only 6% for any patient presenting with an rAAA
(unpublished data). This is truly a transformational event
in the history of vascular intervention.
At Harborview, we use the rAAA protocol with continuing success and have performed EVAR for rupture in nearly 100 patients. Currently, 80% to 90% of patients presenting to Harborview with rAAAs are treated using an EVAR approach. We foresee the gradual diminishment in the use of open rAAA surgical repair except when patients present with anatomical features ruling out the rEVAR option.
BUILDING YOUR CENTER
It is the author's opinion that certain select centers
should seek to build a program for managing rAAAs using an endovascular approach. The creation of an
endovascular ruptured aneurysm protocol requires several
key requisites for success (Table 1). If a provider is practicing
in a hospital that performs only a few of these procedures
per year, that provider should be cautious in
applying endovascular techniques for the management
of rAAAs except in extremely permissive circumstances.
In addition, these procedures must be done in an environment
where the default operative pathway is conversion
to a traditional open procedure. Therefore, a traditional
operating room (OR) with endovascular capability
or a hybrid endovascular/OR suite remain the best
options.
Institutional requirements include the infrastructure to admit patients with rAAAs into an OR quickly. This requires an emergency department (ED) that can rapidly assess and appropriately resuscitate patients and perform CTA when needed within minutes. Also required are quick turn-around times for transferring a patient from the ED into the OR. This often requires repeated rehearsal on the part of the ED staff, radiology and angiography staff, and OR personnel. Key personnel familiar with endovascular techniques need to be available around the clock. At Harborview, a “rupture room” is maintained after hours and on weekends and is reserved only for incoming patients with ruptured aneurysms. This room has a C-arm, power injector, imaging table, and endovascular inventory in the room and ready for use.
One of the advantages of an “all-endo” approach is the ability to sneak into the aorta with the patient awake and place an aortic occlusion balloon above the renal arteries using solely percutaneous techniques (Figure 2). This can be done under local anesthesia (and often no anesthesia) and helps maintain the patient's physiologic state (permissive hypotension). Once the aortic occlusion balloon is in place, the anesthesiology team can then choose a method of anesthesia with an emphasis on keeping the patient awake. We have elected to keep patients awake during EVAR procedures for rAAAs using local anesthesia with sedation only. Morbidly obese patients present challenges with conventional imaging, and it has been our practice to electively intubate these patients once an aortic occlusion balloon has been placed.
ASSEMBLING THE STAFF
A fully trained staff is essential for a successful
endovascular rAAA program. One of the biggest obstacles
to establishing a rAAA program is disrupting the status
quo and changing the mindset of providers who care
for patients with rAAAs. Different specialties are defined
by different “comfort zones.” In managing rAAAs, the
comfort zone of a surgeon is to be in an OR, and the
comfort zone for an anesthesia provider is to have a
patient intubated and under general anesthesia. It only
takes a few successful cases to convince an anesthesiologist
that keeping a patient with a blood pressure of
80 mm Hg hypotensive and awake for rAAA repair can
be life-saving. Our anesthesiologists have moved toward
being very gentle with administrating sedatives during
insertion of the Foley catheter and placement of IVs,
central lines, and an arterial line.
The unfortunate tendency when a patient becomes a little agitated is to reach for whatever anesthetic agent is handy and plow the patient with sedatives. This is exactly what not to do because the patient loses all protective measures, including abdominal wall muscular tone and may become rapidly hypotensive, necessitating urgent intubation and sometimes a rush to convert to open repair (the comfort zone of the nervous endovascular surgeon). Gentle application of anesthetics only until the aortic occlusion balloon is in place is all that is required.
A full complement of endovascular skills is paramount for managing these patients. If certain staff members are uncomfortable with an endovascular approach, those who are comfortable should be immediately available if the patient is a candidate for endovascular repair. These procedures must be done rapidly. It is the author's opinion that if it normally takes a provider more than 1 hour to perform a standard EVAR under elective conditions, that provider should not be managing patients with rAAAs. One of the most time-consuming aspects of any EVAR can be cannulation of the contralateral gate with a guidewire. Preoperative selection of the graft components and delivery site to best allow for rapid gate cannulation will potentially lead to improved outcomes. A protocol should be considered so that in an rAAA setting, if it takes more than 10 minutes to cannulate the contralateral gate, consideration must be given to converting to an aorto-uni-iliac construct. Prolonged EVAR times and gate cannulation times may ultimately directly correlate with the onset of abdominal compartment syndrome and lead to an increase in subsequent morbidity and mortality.
Figure 3 demonstrates a successful repair of an rAAA in which the graft was implanted within 27 minutes of access. Optional and potentially more advantageous approaches to patients with rAAAs involve the use of suture-mediated closure devices for closure of large-bore sheath sites, which saves both time and the potential morbidity for bilateral groin incisions.4
IMAGING SELECTION
Many modern hospitals have built hybrid ORs and
modern imaging suites into their existing ORs. If this
room is empty when an rAAA case arrives, the patient
will ultimately benefit. However, this scenario is not often
realistic, and the default in an emergency situation is to
use portable imaging and an imaging table in whatever
room is available at the time. In the not-too-distant
future, flat-panel rotational detectors and portable
C-arms with superb imaging will be available for managing rAAAs. Intravascular ultrasound is an incredibly useful
tool for intraoperative imaging and sizing if the patient
did not have a CTA before presentation. A power injector
is crucial for appropriate imaging of the aorta using
standard flush aortography. The only factor that is different
from standard equipment available for elective EVAR
is blood preservation and suction equipment. At
Harborview, the Cell Saver (Haemonetic Corp., Braintree,
MA) and Stryker Neptune suction machines (Stryker
Corp., Kalamazoo, MI) are maintained in the rupture
room. If at any time a procedure needs to be converted
or a decompressive laparotomy needs to be done at the
end of the procedure, these machines are critical for
preservation and proper blood collection. Our standard
rupture room setup is depicted in Figure 4.
INVENTORY
Placing the properly sized graft into the patient
requires a full complement of inventory (Figure 5). Also
required is a stock of common catheters, guidewires, and
sheaths just as for standard elective EVAR procedures.
This inventory should be kept as simple as possible. At
Harborview, we have separated the equipment required
for an aortic occlusion balloon set for rapid opening at
the beginning of the procedure (Table 2). Whatever graft
is utilized, once the sizing measurements have been
made, whether intraoperatively or in the ED when the
patient arrives from an outside hospital with a CTA on
transferable electronic media, the graft components
should be chosen, opened, and flushed for immediate
delivery when needed. In the most common scenario at
Harborview, the grafts are opened and prepared before
the patient is prepped.
POSTOPERATIVE CARE
Patients with ruptured aneurysms have unique physiologic
conditions and require a tailored approach to postoperative
management. Surgeons realize that success is not
defined only by a successful operation but by the comprehensive
management of the patient before, during, and
mostly after the operation. Expert intensive care unit management
is essential for establishing a successful endovascular
rAAA program, and implementation of that program
requires a multitude of factors for ultimate success.
CONCLUSION
Creating a seamless endovascular rAAA program can
be challenging but will most assuredly have an impact on
mortality versus historical institutional controls undergoing
open repair. As technology improves, hopefully so
will mortality rates for this deadly condition.
Benjamin W. Starnes, MD, FACS, is Chief, Division of Vascular Surgery, University of Washington, and Chief, Vascular and Endovascular Surgery, Harborview Medical Center, in Seattle, Washington. He has disclosed that he is a consultant to Cook Medical and Abbott Vascular. Dr. Starnes may be reached at starnes@u.washington.edu; (206) 731-3370.
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