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Anesthesia for Diagnostic and Interventional Radiology

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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

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.



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

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:

Angiography/embolization

PIC lines, access catheters

Ureteral stents

Trauma interventional procedures

Thermography of liver 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

     * 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

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



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.



References:
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 Sanderson PM. A survey of pentobarbital sedation for children undergoing abdominal

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 Lefever EB, Potter PS, Seeley NR. Propofol sedation for pediatric MRI. Anesth

Analg 76:919-20, (letter) 1993.



Frankville DD, Spear RM, Dyck JB. The dose of propofol required to prevent children

from moving during magnetic resonance imaging. Anesthesiology 79:953:1993.



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 Scand 40:561, 1996.



 Bloomfield E, Intravenous sedation for MR imaging of the brain and spine in

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 Langton JA, Wilson I, Fell D. Use of the laryngeal mask during magnetic resonance

imaging. Letter. Anaesth 47, 6:532, 1992.



 American Academy of Pediatrics, Committee on Drugs, Section on Anesthesiology.

Guidelines for monitoring of pediatric patients during and after sedation for diagnostic

and therapeutic procedures. Pediatrics 89:1110, 1992.



 Morello FP, Donaldson JS, Saker MC, et al. Air embolism during tunneled catheter

 placement performed without general anesthesia in children: a potentially serious

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 Jordan WD, Voelinger DC, Fisher WS, et al. A comparison of carotid angioplasty

 with stenting versus endarterectomy with regional anesthesia. J Vasc Surg 29(4):757,

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44:26-30, 1997



Edmonds-Seal J, du Boulay G, Bostick T: The effect of intermittent positive pressure

ventilation upon cerebral angiography with special reference to the quality of the

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Young WL, Pile-Spellman J. Anesthetic considerations for interventional

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Vinuela F, Duckwiler G, Mawad M. Guglielmi detatchable coil embolization of acute

intracranial aneurysm: perioperative anatomical and clinical outcome in 403 patients.

J Neurosurg 86(3):475-82, 1997.



Pile-Spellman J, Young WL, Joshi S, Duong DH, Vang MC, Hartmann A, Kahn RA,

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report. Neurosurgery 44:881-6; discussion 886-7, 1999.

				
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