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Anesthesia for Diagnostic and Interventional Radiology
Introduction
The continuous advancement in diagnostic and interventional radiology techniques
has led to increased demand for anesthesia services. The anesthesiologist can provide
comfort and safety for the patient and perhaps contribute to the success and efficient
completion of the procedure. This discussion will review the anesthetic
considerations for management of a variety of procedures throughout the radiology
suite.
Diagnostic procedures are often noninvasive or without intense stimulation. Although
some are painful, others may be safely executed with only intravenous sedation.
Some studies may be prolonged with risk associated with movement and are best
performed under general anesthesia. Little is gained from a technique that yields an
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inadequate study. The anesthesiologist must treat each patient as unique and not abide
by routine.
Risk factors associated with sedation complications:
Depth of sedation/anesthesia
Skill and training of practitioner
Age of the patient
Drugs used
Monitors used
Magnetic Resonance Imaging:
MR is utilized for a multitude of diagnostic studies. The excellent resolution of MR
can be severely degraded by any patient movement. In addition, the required intense
magnetic fields create unique problems with the use of physiologic monitors, standard
anesthesia machines, and ventilators.
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Anesthetic Considerations:
Magnetic field disables monitoring equipment
RF interference and risk of burns
Hazards of ferromagnetic projectiles
Patient distance/ inaccessibility
Prolonged studies
Distance from operating room/ post anesthesia care unit
While pediatric patients constitute the largest group requiring sedation, adults with
claustrophobia and critically ill or uncooperative patients may require anesthetic
assistance. The goal of anesthesia for MRI is to provide immobility, safety and
comfort for the patient while achieving the best diagnostic study. MR imaging data is
acquired in 8-10 minute sequences; if patient movement occurs during that time the
entire sequence must be repeated.
Anesthetic techniques include:
Chloral hydrate, given orally or per rectum
Pentobarbital, intravenous or orally administered
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General anesthesia with ETT or LMA
Propofol infusion with spontaneous ventilation /controlled ventilation
Anesthetic technique is determined by the age of the patient, presence or ability to
obtain an intravenous line and available equipment (anesthesia machine, ventilator).
A frequent option is propofol infusion, this is preferable for children over 3 years of
age. A bolus induction dose of 1-2 mg/kg is given followed by continuous infusion
with spontaneous ventilation. The patient is positioned such that the airway remains
open and a regular pattern of respiration is observed without signs of airway
obstruction. The infusion rate of propofol that maintains this state is approximately
75-100 ug/kg/min. Many infusion pumps are rendered inoperable by the magnetic
field or will function only at a considerable distance from the MR scanner (up to 6
feet). An alternative technique is the use of a gravity-fed infusion device or “drip
chamber”. This allows easy titration of a dilute solution of propofol (3-5 mg/cc).
While many consider this technique a form of “deep sedation”, it is actually total
intravenous anesthesia and should be monitored carefully. Monitoring should include
pulse oximetry, capnography, and non-invasive blood pressure.
Interventional Radiology procedures:
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Angiography/embolization
PIC lines, access catheters
Ureteral stents
Trauma
interventional
procedures
Thermography of liver metastases
These are more painful procedures requiring patients to lie supine without movement.
Debilitated patients require careful attention and monitoring. Sedation/analgesia
techniques or general anesthesia are options for management.
TIPS- Transjugular intrahepatic portosystemic shunt
Performed for patients with severe liver disease causing elevated portal venous
pressure
Right int jugular cannulation>catheter through RA to right hepatic vein
* Respiratory motion control during passage into portal vein
* Airway management in face of rapid GI hemorrhage
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* Potential liver capsule laceration with intraperitoneal hemorrhage
Anesthetic technique depends on the severity of disease and degree of ascites.
Interventional Neuroradiology (INR) procedures:
Endovascular embolization of AVM’s
Endovascular treatment of ruptured aneurysms
Sclerotherapy of venous angiomas
Balloon angioplasty of occlusive cerebrovascular
disease
Thrombolysis of acute thromboembolic stroke
Carotid angioplasty with stent
INR procedures are performed electively or urgently for a variety of CNS
pathologies. Despite concern for neurologic evaluation, most neuroradiologists now
prefer general anesthesia (with apneic periods) for optimal imaging of studies and
techniques. Monitoring may include intra-arterial and central venous pressure
catheters as well as neurophysiologic assessment. Additional goals may include
optimizing intracranial dynamics and induction of hypertension/hypotension/asystole
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when
necessary.
A
rapid return to
consciousness
is appreciated
at the end of these procedures.
Aneurysm ablation- Radiology Suite vs. OR
Location/ anatomy of the aneurysm
Age and grade of the patient
Skill of the facility
Luck of the draw
Potential complications:
Contrast reactions
Embolization of particles
Aneurysm perforation
Cerebral ischemia
Obliteration of physiologic arteries
Brain swelling
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Knowledge of the risks and hazards of the
different procedures and close collaboration with
the
neuroradiologist
form
the
basis
for
appropriate management of a potentially fatal ischemic or hemorrhagic complication
that may occur in 1-8% of cases.
Conclusion
The continued success of diagnostic and therapeutic interventional radiology is
dependent upon patient safety and acceptance. The ever-increasing trend toward
minimal invasiveness and ambulatory care mandates that better techniques evolve for
patient recovery and well-being. Adherence to standards of care and development of
safe practice patterns will provide for patient safety and continued scientific
advancement.
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