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CHAPTER 30: Interventional Radiology 209

CHAPTER Interventional Radiology and may poorly tolerate attempts to initiate therapy at bedside. Clearly,
there are exceptions and the risks and benefits of any therapy are dic-
30 Brian Funaki tated by local expertise and must be carefully considered and discussed
among the ICU team and IR team.
Jonathan M. Lorenz
Rakesh Navuluri PREPROCEDURAL PREPARATION
Thuong G. Van Ha
Steven M. Zangan It is especially important for critically ill patients to be properly prepared
for IR therapy. If patients are obtunded or combative and will be unable
to lie still, a consultation with an anesthesiologist is strongly recom-
KEY POINTS mended. When possible, coagulopathies should be corrected. When this
is not possible, procedures should be delayed or modified. For example,
• Interventional radiology (IR) provides a gamut of minimally inva- an arterial sheath may be left in place after completion of angiography to
sive therapies well suited for the critical care patient population. be removed later. Heparin should be discontinued at least 2 hours prior
• The dictum of “smaller, faster, safer, better” is the ideal of minimally to procedures and restarted 6 to 8 hours after completion of procedures
invasive image-guided therapy. In the appropriate patient, this type of as a drip (no bolus). If the patient is allergic to contrast, preprocedural
therapy is invariably better tolerated than more invasive techniques. medications should be given whenever possible.
• Three primary image modalities are used to guide IR procedures: Acceptable guidelines will vary slightly from institution to institution
fluoroscopy, computed tomography (CT), and ultrasound (US). but general guidelines for patients to undergo IR therapy are
Increasingly, hybrid suites are equipped with all three modalities • International normalized ratio <2.0
• Appropriate ICU-monitoring devices and support personnel must • Platelets >75,000
be available in the IR suite to best serve the critical care population.
• Contrast allergy premedication: methylprednisolone 32 mg, 12 and
2 hours prior to contrast administration, diphenhydramine 50 mg, 1 hour
before contrast administration (ACR Manual on Contrast Media, 2010)
Interventional radiology (IR) is a field of medicine devoted to using
image-guided minimally invasive techniques to improve patient care. If the patient has renal insufficiency, this should be discussed with the
Rather than being unified by an organ system or disease, interventional interventional radiologist because iodinated contrast material is nephro-
radiologists are guided by the dictum of “smaller, faster, safer, better” toxic and should be avoided unless absolutely necessary. In many cases,
therapy. As such, the interventional radiologist treats patients of all demo- alternative contrast agents such as carbon dioxide may be used to facilitate
graphics. Commonly, IR procedures are performed instead of traditional therapy. Carbon dioxide enhancement may be used to guide inferior vena
open surgical procedures because minimally invasive procedures are often cava (IVC) filter insertion, transjugular intrahepatic shunt creation, and to
better tolerated with less morbidity and lower mortality. This is particu- perform diagnostic angiography below the chest. In the past, gadolinium
larly important in critical care patients who often have significant comor- was used in patients with renal insufficiency. Currently, due to the associated
bidities. The overwhelming majority of procedures offered in the IR suite risk of nephrogenic systemic sclerosis, this practice has been discontinued.
are performed using conscious sedation, which also tends to limit risks
associated with these therapies. As such, it is critical that patients be able PATIENT MONITORING IN IR
to minimally cooperate with interventional radiologists. If patients are While the level of monitoring equipment and specialized staff varies
combative or unable to lie still, anesthesiologists may be required to assist.
from institution to institution, in general, all state-of-the-art IR suites
are outfitted with basic patient monitoring equipment including elec-
WHERE SHOULD THERAPY BE PERFORMED? trocardiography, noninvasive pulse oximetry, and automated blood

Provided appropriate personnel and monitoring devices are available, pressure monitoring. Wall suction and oxygen are also ubiquitous and
as a general rule, the safest and best place to perform an IR procedure newer rooms can monitor end-tidal carbon dioxide, which can detect
is unquestionably in the IR suite. Some very straightforward procedures respiratory depression sooner than pulse oximetry. Every IR suite is
such as drainage of a large, superficial abscess can be done at bedside staffed with at least one technologist and one nurse in addition to the
but there are significant disadvantages to initiating IR therapy in the physician(s) providing therapy. In our hospital, the majority of our IR
ICU. First, the safety and effectiveness of nearly all IR procedures are nurses have ICU experience; during procedures, they administer seda-
predicated on high-quality imaging. In many procedures, more than one tion (typically midazolam and fentanyl) and monitor the patient.
imaging modality is used in an IR suite to provide the largest margin of Critically ill patients from the ICU should be accompanied to IR
safety. For example, when cholecystostomy is performed in the IR suite, with equipment and staff that can handle any additional life supportive
the gallbladder is punctured using ultrasound (US) guidance and the measures. In the authors’ opinion, patients are best served if a physician
remainder of the procedure is completed using fluoroscopic guidance. from the ICU also accompanies the patient to the IR suite. In a very
While it is possible to perform the procedure using only US guidance at practical sense, it is impossible for an interventional radiologist to both
bedside, sonographic visualization of needles, wires, dilators, and tubes competently perform an image-guided procedure while simultaneously
may be limited, particularly in large patients. Portable fluoroscopy units directing supportive therapy in a critically ill patient unfamiliar to him
are typically inadequate because they are awkward, have a small field of or her. Optimal patient care dictates constant communication and close
view, and provide no meaningful radiation shielding. Second, and more cooperation between the ICU and IR services throughout this process.
importantly, an interventional radiologist has a limited ability to recog-
nize and treat any complication that occurs during a bedside procedure. PERCUTANEOUS ABSCESS DRAINAGE
Complications that may prove lethal at bedside may be easily handled in
an IR suite given the superior imaging and immediate access to special- KEY POINTS
ized catheters and other equipment. One common dilemma involves the
patient who needs an IR therapy but is “too unstable” to travel to the IR • Percutaneous abscess drainage is the treatment of choice for
suite. In our collective experience, as a rule of thumb, patients that are infected, well-defined fluid collections.
too unstable to travel are usually also too unstable to undergo IR therapy

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