Page 317 - Hall et al (2015) Principles of Critical Care-McGraw-Hill

CHAPTER 30: Interventional Radiology 221

be used in place of embolization when superselective catheterization is
not technically achievable, such as in patients with tortuous vessels or These newer devices may be removed within a prescribed time
vasospasm. While it can be effective in treating lower GI bleeding, vaso- period if caval filtration becomes unnecessary.
pressin has not been shown to be effective for upper GI bleeding. The • Some retrievable filters appear to have more complications (migra-
relatively larger vessels from which upper GI hemorrhage usually arise tion, strut perforation) compared to permanent filters.
may not constrict to the same degree as smaller branches associated with
lower GI bleeding.
artery or cerebrovascular disease as these conditions may be exacerbated ■ INDICATIONS AND PATIENT SELECTION
Vasoconstrictor infusion is contraindicated in patients with coronary
by vasopressors. Cardiovascular complications are reported to occur Venous thromboembolic (VTE) disease refers to deep vein thrombosis
in 5% to 8% of patients, including arrhythmias, myocardial infarction, (DVT) and its most severe complication, pulmonary embolism (PE). PE
and hypertension. These effects can be lessened to some degree by the is a significant cause of morbidity and mortality in hospitalized patients
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concomitant administration of nitroglycerin. Additional complications and in ICU patients in particular. Medical therapy remains the first-line
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include catheter dislodgement with infusion into a nontarget artery, treatment for DVT and PE with heparin, low-molecular weight heparin,
and thrombosis secondary to prolonged catheterization. Overaggressive or warfarin. The rationale behind medical management is to reduce risk
treatment with vasopressin can also lead to mesenteric artery throm- of clot extension with rapid initial anticoagulation followed by long-term
bosis and bowel infarction. Because of these potential complications, anticoagulation to reduce risk of VTE recurrence. When the risk of
intensive care unit admission is usually required when using vasopressor treatment exceeds risk of recurrent VTE, anticoagulation is terminated.
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therapy. Abdominal cramping and evacuation of accumulated blood Anticoagulation is associated with a small risk of hemorrhage in many
within the bowel can be a normal occurrence during the initial infusion patients but in some, bleeding risks can be significant. Patients at risk of
due to the effects of vasopressin on intestinal smooth muscle. If cramp- bleeding include those with thrombocytopenia, gastrointestinal hemor-
ing does not subside within an hour, or if it recurs during the infusion rhage, intracranial metastases, and coagulopathies. In this group, IVC
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period, there should be concern for bowel ischemia. In these events the filter placement should be considered instead of anticoagulation.
vasopressin dose should be titrated down until the pain is relieved. Indications for IVC filter placement can be divided into therapeutic
Success rates range from 60% to 100%, with the best results obtained and prophylactic. Therapeutic indication refers to documented VTE,
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when treating colonic diverticular bleeding. Rebleeding is a commonly specifically PE or DVT in the IVC, iliac, and femoral-popliteal system,
cited drawback to vasopressin use with rates ranging from 36% to with (1) contraindication to anticoagulation, (2) complication from anti-
43%. It is suspected to occur when the vasospasm-induced thrombus coagulation, and/or (3) failure of anticoagulation, that is, recurrent PE
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is resorbed before the underlying vascular lesion heals. The recurrence or DVT progression despite adequate anticoagulation. Therapeutic filter
rate is higher with vasopressin infusion compared with embolotherapy. placement may also be indicated in some patients with massive PE and
It is also worth noting that vasopressin may be ineffective in the setting residual DVT, in patients at risk for further PE, free-floating iliofemo-
of extensive atherosclerosis, which prevents adequate vasoconstriction. ral or IVC thrombus, and severe cardiopulmonary disease with DVT.
■ VARICEAL BLEEDING Prophylactic indications remain controversial and refer to cases of filter
placement without the existence of VTE. These include severe trauma
Variceal sources of GI bleeding are distinct from arterial bleeding (closed head injury, spinal cord injury, multiple long bone, or pelvic frac-
both in etiology and endovascular treatment. For these reasons, it is tures) and other high-risk patients. With the advent of retrievable filters,
important to distinguish between nonvariceal and variceal sources of prophylactic placement has increased. Currently prophylactic filter use
hemorrhage at the outset. Sources of variceal bleeding include gastro- accounts for more than half of all filter placement, a significant increase
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esophageal varices from portal venous hypertension (eg, secondary to from 19% in 1999. This correlates with a shift in use from permanent
cirrhosis or Budd-Chiari syndrome), and gastric varices from splenic filters to retrievable filters and to a large increase in overall filter usage,
vein thrombosis. It is important to recognize that 30% of patients with from 49,000 in 1999 to an estimated 259,000 in 2012. 50
portal hypertension who present with upper GI bleeding actually have In general, filter deployment systems are low in profile and range
an arterial source of bleeding. Reduction of the portal-venous gradi- from 6F and 12F, making percutaneous placement relatively safe and
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ent usually necessitates a transjugular intrahepatic portosystemic shunt reliable. In addition, the percutaneous approach can be used to perform
(TIPS) creation with or without concomitant variceal embolization. additional procedures such as pulmonary arteriography, central venous
Gastric varices represent a slightly different pathology and hemody- pressure measurements, and central venous catheter insertion, if needed.
namic issue than esophageal varices. The majority of gastric varices are due A number of filters are available commercially and can be divided
to portal hypertension, while others are secondary to splenic vein throm- into permanent and nonpermanent types. Nonpermanent types include
bosis. BRTO is a highly effective and minimally invasive treatment for retrievable, temporary, and convertible filters. Some practitioners refer
gastric varices particularly in patients who are not suitable candidates for to the retrievable types as optional as they are approved to be both per-
TIPS due to poor hepatic reserve. This procedure utilizes an occlusion bal- manent and retrievable. The term temporary is currently used to describe
loon in order to control the blood flow through prominent draining veins a filter that is tethered to a catheter or wire, which protrudes outside the
of portosystemic shunts (most commonly a gastrorenal shunt) contribut- patient and must be removed in period of days, not unlike a nontunneled
ing to the gastric varices. With the shunt outflow occluded, the goal is to central venous catheter, to prevent infection. These types of filter are no
sufficiently fill the variceal complex with a sclerosing agent and obliterate longer commercially available in the United States. Another type of filter
the gastric varices without refluxing into the systemic or portal circulation. is the convertible filter, referring to a type of filter that can be structur-
ally altered to no longer function as a filter but remains in the IVC. No
INFERIOR VENA CAVA FILTER PLACEMENT convertible filters are currently approved for use in the United States.
The Society of Interventional Radiology Guidelines for use of IVC
filters states that there are no unique indications for optional vena caval
KEY POINTS filters that are distinct from the permanent types and that the discon-
tinuation of filtration should occur only when the risk of clinically
• Retrievable IVC filters are increasingly inserted in patients requir- significant PE is reduced to acceptable level and is less than the risk of
ing caval filtration. having an indwelling filter (Fig. 30-14). 51
• Retrievable filters have similar indications as permanent filters Over the last decade, retrievable or optional filters have come to dom-
(eg, failure, complication, or contraindication to anticoagulation). inate the filter device market. 52,53 Some retrievable filters are designed
with a hook at one end that can be engaged using a snare device,

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