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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_3733_Библиотеки_им_академика_М_И_Перельмана.pdf
one-half of the lymphoid tissue in the body; is a reservoir of macrophages,
which remove bacteria and red blood cells infected with parasites; and
produces vital immunomodulators such as opsonins, which are needed to
clear encapsulated organisms. Asplenic patients are probably more
susceptible to gram-negative bacteria and fungi as well.12 Splenectomized
patients should be immunized against Streptococcus pneumoniae,
meningococcus, and Haemophilus influenzae type B, the encapsulated
organisms for which vaccines are currently available.
12,16,17
The trend toward conservative management of splenic injury coincided
with the development of endovascular techniques to achieve hemostasis and
support organ preservation. Although balloon occlusion and gelatin foam
embolization had been previously reported,
18,19
in 1981, Sclafani20 described
endovascular occlusion of the proximal main splenic artery with coils, and he
predicted that this would improve the outcomes of NOM. In 1991, Sclafani
and his colleagues21 reported a striking 97% splenic salvage rate with routine
angiography and selective proximal splenic artery occlusion in patients with
splenic lacerations diagnosed with CT.
The specific indications and most appropriate candidates for NOM and
adjunctive angioembolization have been a topic of debate and many
retrospective studies in the intervening period; the object has been to
elucidate the vital factors which contribute to the success or failure of
conservative management. Failure is indicated by continued or recurrent
splenic bleeding, often referred to as delayed splenic rupture. Peitzman et
al.22 found that the success of NOM is directly correlated with increasing
hematocrit and blood pressure and inversely correlated with OIS grade and
quantity of hemoperitoneum. Advanced age has been shown to be a risk
factor; Renzulli et al.23 found age older than 55 years to be the only
independent risk factor for failure of NOM. The direct relationship between
increasing OIS grade and failure rate of conservative therapy has been
demonstrated in multiple retrospective analyses.
22,24–27
Patient Selection
Most large trauma centers include splenic artery embolization (SAE) as a
variable component of NOM. Much of the current literature supports
angiography for hemodynamically stable patients with CT findings
suggesting contrast extravasation and/or grade IV or V injuries. Several
studies have demonstrated that in low-grade injuries (OIS I to III),
angioembolization does not result in an improvement in outcomes, whereas
in higher grade injuries, a marked improvement is seen.
25–27
For example,
Requarth et al.27 showed that although failure of nonoperative management
(FNOM) was less than 5% in OIS grades I and II injuries with or without
SAE, it rose with each OIS grade to 83.1% in grade V observation-only
patients but only to 25% in patients who underwent SAE.
Although most trauma centers include angiography and embolization as
an adjunct to NOM of splenic trauma in hemodynamically stable patients,
there are no randomized trials. Thus, the Eastern Association for the Surgery
of Trauma (EAST) assigns a level 2 recommendation to use SAE in grades
IV and V injuries or whenever contrast extravasation is noted on CT.
8
Bhullar et al.28 supported this recommendation in a 2013 study, pointing out
that significantly higher failure rate of NOM in grades IV and V injuries may
be affected by the fact that many centers do not perform angiography in cases
where extravasation is not noted on CT. Although evidence of active
bleeding is more common in higher grade injuries, it may be seen in lower
grade (OIS I to III) injuries as well.
Technique
If the splenic artery is clearly identified on the admission CT, a flush
aortogram may not be necessary before splenic artery selection. Typically, a
Cobra (Angiodynamics, Latham, New York) or reverse curve catheter such
as an Sos or Mikaelsson (Angiodynamics, Latham, New York) is used to
select the celiac axis. Splenic angiography should be performed with
automated injection. If angiography reveals active extravasation, then
selective distal coil embolization may be performed using a microcatheter
with microcoils and/or gelfoam, followed by proximal main splenic artery
coil embolization (Fig. 22.1). If there is no evidence of active hemorrhage,
then only proximal main SAE is performed using coils, either via the main
catheter or a microcatheter.
The rationale for proximal main SAE is reduction of splenic blood
pressure, facilitating hemostasis without causing infarction. The abundant
arterial supply to the spleen makes this possible. Perfusion is maintained by
pancreatic, omental, and short gastric arteries at relatively lower pressure,
which gives splenic vascular injuries an opportunity to heal; as the collateral
arteries enlarge, pressure is believed to eventually return to preembolization
levels, although when this happens is unknown.
29,30
Requarth and
colleagues30 conducted a study demonstrating significant variability in the
distal splenic arterial pressure during proximal balloon occlusion of the
splenic artery. They concluded that some patients, such as those with celiac
stenosis, might already have well-developed splanchnic collaterals, which
would negate the impact of proximal splenic artery occlusion on parenchymal
pressure. Interestingly, their results suggest that it may be reasonable to
perform splenic artery balloon occlusion with pressure measurements in all
splenic trauma patients before deciding whether to embolize; patients who do
not demonstrate a significant decrease in splenic artery pressure during
balloon occlusion may be better served with either surgery or observation.
The diameter of the splenic artery should be measured and coils
oversized by at least 2 mm to avoid coil migration and increased risk of
splenic infarction. Appropriate sizing is difficult. Detachable coils allow the
operator to retract a partially deployed coil if it appears that migration is
likely. For proximal main SAE, coils should be placed distal to the dorsal
pancreatic artery and proximal to the greater pancreatic artery (often called
by its Latin name arteria pancreatica magna), although the ideal location is
not known (Fig. 22.2). The dorsal pancreatic artery is usually the largest
splenic artery branch to the pancreas and there is at least a small risk that
occluding this vessel could lead to pancreatic ischemia.29 It also gives rise to
distal branches that become a collateral source of splenic perfusion after
occlusion of the splenic artery. However, there is variability in the anatomic
origins of these pancreatic branches, and they cannot always be identified
with certainty. The omental and short gastric arteries, left gastroepiploic
artery, and other branches from the inferior and caudal pancreatic artery will
also serve as collateral blood sources for the spleen after proximal
embolization.
29,30
Postembolization angiography should demonstrate
occlusion of the main splenic artery with delayed splenic parenchymal
perfusion via collateral flow.
Results
In a comprehensive retrospective analysis of 33 blunt splenic injury outcomes
articles from 1994 to 2009 by Requarth et al.,27 patients were stratified based
on type of NOM (with or without SAE) as well as splenic injury grade. They
found the overall failure rate of observational management to be 17%, with
much worse rates of 44% and 83% in grades IV and V injuries,
respectively.27 However, SAE significantly decreased the failure rates in
grades IV and V to 17% and 25%, respectively.27 Bhullar et al.28 found a 4%
failure rate in patients with high-grade splenic injuries who underwent SAE,
including those with contrast blush on CT, only 9% of whom ultimately
required laparotomy (splenectomy or splenorrhaphy). In one of the largest
single-center studies using a protocol of selective embolization in patients
with CT evidence of vascular injury or active bleeding, Sabe et al.31 reported
an NOM success rate of 97%. Banerjee et al.32 compared outcomes across
four level I trauma centers with varying rates of embolization and found that
SAE is an independent predictor of spleen salvage; centers in which it was
used more had higher NOM success rates. Haan et al.33 published another
large single-center study which demonstrated 90% success overall with NOM
and over 80% success in grades IV and V splenic injuries. Many of the
successful cases had CT scans demonstrating pseudoaneurysm or active
extravasation and were treated with SAE. However, in patients with traumatic
arteriovenous fistula (AVF), failure rates were high (40%) even after SAE.
They concluded that AVF requires direct embolization and that proximal
SAE is insufficient in these cases.
33
In cases of late rebleeding after observation or SAE, it appears that
many, if not most, centers favor splenectomy even though conservative
management has become standard therapy for acute splenic injury. The
reasons for this are unclear but likely reflect a reluctance to continue with a
“failed” strategy. In a paper by Liu et al.,34 15 cases of “delayed splenic
rupture” were reviewed. Twelve were treated nonoperatively with 83%
success rate, and 5 of these underwent SAE with 80% success rate. These
results are comparable to those of primary NOM with or without SAE and
they conclude that embolization is a reasonable strategy for late rebleeding.
34
The most common complication directly related to SAE is splenic
infarction, of which there is a higher risk when distal embolization is
performed.
35,36
The clinical significance of these typically small or segmental
splenic infarcts is unclear, as most ultimately resolve without further
intervention.35 In a meta-analysis by Schnuringer et al.,35 no difference in the
rate of major complications such as large infarct or abscess requiring
splenectomy was found when comparing proximal and distal embolization
techniques. Other complications are predominantly technical and rare,
including arterial dissection, coil migration into the aorta, and femoral artery
pseudoaneurysm.
36
Protocols regarding observation, discharge, and follow-up imaging vary
but typically include inpatient stay of 3 to 5 days, as recommended by
Peitzman et al.22 Rebleeding, the most common cause of failure, most often
occurs within 3 days of injury.
37,38
Smith et al.38 demonstrated that 95% of
failures would be detected within 3 days. Significantly improving this risk is
unlikely because statistically, to detect 99% of failures, 30-day observation
would be required.38 Most surgeons do not perform routine postdischarge
imaging.9 This is supported by a study by Haan and colleagues37 examining
splenic pseudoaneurysms after NOM. In their series, distal splenic
embolization was only performed if free extravasation of contrast was seen at
angiography. Pseudoaneurysm, AVF, and extravasation confined to the
spleen were treated with proximal SAE. Patients found to have persistent or
new pseudoaneurysms on follow-up CT after NOM had similar splenic
salvage rates (94%) without additional therapies. Most pseudoaneurysms had
resolved on follow-up imaging.
37
Finally, the question of immunocompetence after splenic
angioembolization has been addressed in several papers. Although our
understanding of immunomodulating functions of the spleen is incomplete,
authors of several studies have concluded that there is no evidence that
immune function is significantly affected by SAE.
17,39
Therefore,
immunization is not recommended for these patients.
TIPS AND TRICKS
• When performing a proximal SAE, ideal coil deployment is between
the dorsal pancreatic and great pancreatic artery (also known as
arteria pancreatica magna). Given the anatomic variability and often
poor visualization of these branches, a good rule of thumb is to
deposit coils at the junction of the proximal and middle third of the
splenic artery.
• Sizing coils for a proximal SAE can be difficult. Detachable coils or
Amplatzer Vascular Plugs (St. Jude Medical, Inc., St. Paul,
Minnesota) may be partially deployed and retrieved if they do not
“hold,” which helps to avoid distal coil migration.
• Selective distal coil occlusion should only be performed if there is
active extravasation, pseudoaneurysm, or AVF. Given the likelihood
in high-grade injuries of other vascular lesions that may not be
evident on angiography due to thrombus or vasospasm, this should be
followed by proximal SAE.
LIVER
Hepatic arterial embolization, similar to splenic embolization, is an important
adjunct in the NOM of liver trauma, although technique, rationale, and
complications are different. Owing to the greater inherent difficulty of
controlling hemorrhage from hepatic compared to splenic injury, angiography
and embolization may play a larger role during and after surgery.40 This is
because high-OIS-grade liver injuries often produce arterial bleeding, which
is well controlled by transarterial embolization, as well as venous bleeding,
which is not.41 Juxtahepatic venous hemorrhage often requires laparotomy,
sometimes with perihepatic packing and temporary closure (“damage
control”) for the most critical patients.
40–42
In many modern operating rooms
which are equipped with adequate fluoroscopy, embolization of deep,
surgically inaccessible arterial bleeding can be accomplished immediately
after laparotomy.
Identifying the patients with injuries to the retrohepatic inferior vena
cava and hepatic veins therefore is vital. In a 2003 paper by Mohr et al.,
43
patients with juxtahepatic venous injuries had the highest mortality rates
among liver injuries. However, according to Hagiwara and colleagues,41 CT
has low specificity and positive predictive value for venous injury. In their
2002 prospective study of liver trauma patients, the highest sensitivity,
specificity, and positive predictive value of juxtahepatic venous injury was
resuscitative requirement of greater than 2 L of fluids per hour.41 Although
most would agree that these patients are not stable and should be brought to
the operating room, in a 2009 paper by Misselbeck and colleagues,44 52% of
patients who underwent laparotomy for hepatic injury demonstrated
continued postoperative arterial bleeding requiring embolization. In the same
study, patients with CT evidence of active extravasation were 20 times more
likely to have positive angiograms compared to those with no evidence of
active hemorrhage on CT.44 The 2012 EAST guidelines assign a level 2
recommendation to angiography with embolization in patients who are
transient responders to resuscitation as an “adjunct to potential operative
intervention.”
7
Technique
Hepatic angiography should generally begin with flush aortography due to
the high incidence of variable anatomy. A 5-Fr catheter is used to select the
celiac axis and angiography is performed from the common hepatic artery.
Even if there is no evidence of hemorrhage, selective angiography should be
performed with a microcatheter targeting areas of extravasation identified on
CT. In contrast to proximal splenic artery occlusion in which decreasing
blood pressure to the spleen is the primary goal, the goal in hepatic injury is
to embolize distally where there is evidence of hemorrhage (Fig. 22.3). The
dual arterial and portal venous blood supply to the liver likely confers some
protection from ischemic complications, but proximal hepatic artery
occlusion is typically unnecessary and may be detrimental, particularly in
patients with preexisting liver disease or compromised portal venous blood
flow.
The choice of embolic material depends on the extent of the injury and
how distal the microcatheter can be placed. If there is a wide area of arterial
extravasation or the patient is decompensating, relatively proximal
embolization with particles or gelfoam slurry may be necessary to achieve
rapid hemostasis. However, it must be understood that this will increase the
risk of hepatic failure or necrosis requiring operative debridement. If the
hemorrhage is focal, superselective catheterization is preferable. Microcoils,
particles, and gelfoam have all been used successfully. However, the
presence of bile is a unique and possibly complicating feature of liver
lacerations because it inhibits granulation and scar formation, thereby
arresting the normal reparative process.45 Biloma formation is a known
complication of hepatic trauma, occurring after 2% to 8% of cases.
46
Theoretically, therefore, use of gelfoam, which causes temporary vascular
occlusion, may increase the risk of pseudoaneurysm formation because in the
presence of bile, there may not be sufficient time for healing of vascular
injuries before recanalization occurs. Hagiwara et al.46 presented evidence
supporting this theory in a small review of 11 patients with posttraumatic
biloma; pseudoaneurysm formation was significantly more likely in patients
initially treated with gelfoam embolization compared to those embolized with
metallic coils. Although this was a small retrospective study, their conclusion
that in the liver, permanent coil embolization is preferable to gelfoam when
technically feasible is worth considering.
46
Results
The safety and efficacy of hepatic arterial embolization for hemodynamically
stable trauma patients has been established.
40,41,43,44,47
Clinical success rates
of greater than 90% have been reported by several investigators.
48–50
Complications of severe hepatic injury, such as biloma, necrosis, and abscess,
have been reported to occur in up to 50% of cases and are similar to those
which could be attributed to embolization. Mohr et al.43 reported the
occurrence of such complications in 58% of hepatic trauma patients in her
series and concluded that liver-related morbidity is not increased or decreased
by angioembolization. Gallbladder ischemia and necrosis, however, can often
be attributed directly to embolization; Mohr et al.43 and Misselbeck et al.
44