ANESTHESIA OUTSIDE THE OPERATING ROOM

General Considerations/Safety

•  Thorough preoperative evaluation of every pt is essential

•  All patients receiving any form of anesthesia must have ASA monitors during anesthesia care

•  Transport equipment should be available (bag-valve-mask with O₂ tank)

•  Emergency drugs should be available & IV access assessed

•  Postop care & standards are the same as for OR-based anesthesia

•  Pay attention to possible allergies to contrast dye

CT/MRI/INTERVENTIONAL NEURORADIOLOGY

CT: General Considerations

•  Pt should wear lead with thyroid shield at all times while in CT scanner

CT: Monitors

•  Regular OR anesthesia monitors may be used

• Standard ASA monitors required if any anesthesia given

CT: Anesthetic Considerations

•  Anesthetic options range from mild sedation to general anesthesia

•  Patient factors to consider: Pt cooperation, claustrophobia, comorbidities, age, mental status, length of scan

•  Ensure adequate length of IV lines, anesthesia circuit, monitoring wires

Special Procedures in the CT Suite

Stereotactic Brain Biopsy

•  Metal frame placed to perform procedure (usu with local + benzodiazepine)

•  Technique: MAC, titrate sedation carefully to avoid airway compromise if GA necessary, awake fiberoptic intubation may be the safest technique

Percutaneous Vertebroplasty

•  Indication: Reverse vertebral collapse in osteoporotic patients

•  Technique: Usually MAC (or GA if pt in excessive pain)

•  Patient is in prone position → consider pelvic/chest support to avoid impinging on abdomen and interfering with ventilation

MRI: General Considerations

•  Indications for anesthesia care: Children, mentally challenged, claustrophobic pts, pts with resp difficulty, hemodynamically unstable pts, chronic pain pts

•  Distinct features of anesthesia in MRI:

• Powerful magnet

• Remove ferromagnetic equipment: Stethoscopes, credit cards, USB drives, pens, keys, IDs, beepers, cell phones

• Metals safe: Beryllium, nickel, stainless steel, tantalum, & titanium

• Difficulty accessing airway

• Carefully titrate sedatives & have monitors facing clinician at all times

MRI: Monitors

•  Nonferrous monitoring equipment needed

•  Nonmagnetic laryngoscopes for emergencies

•  Ensure adequate length of IV lines, anesthesia circuit, monitoring wires

Interventional Neuroradiology

General Considerations

•  Standard ASA monitors; if arterial line necessary, can be radial or through femoral sheath

• Femoral sheath a-lines → only MAP is useful

•  Technique: GA if motionless state required; sedation if rapid neurologic testing essential or for most diagnostic scans

Deliberate Hypertension

•  May be necessary to help radiology catheters flow to desired location

•  Usually 20–40% above baseline; phenylephrine infusion may be useful

Deliberate Hypotension

•  May be required in carotid endarterectomy/arteriovenous malformation (AVM) procedures

•  Various approaches may be used (↑ anesthesia, labetalol, vasodilators—nitroprusside/nitroglycerin/hydralazine)

Embolization of Arteriovenous Malformation (AVM)

•  Polyvinyl alcohol (PVA) injected into feeding vessels of AVM

•  Approach: MAC (can continuously monitor neuro status) or GA

•  Systemic heparinization may be required

•  Complications: Hemorrhage 2° to anticoagulation (can reverse with protamine), hemorrhage 2° to thrombus (can ↑ BP by 20–40 mm Hg); ↑ ICP (treat with hyperventilation, head ↑, mannitol, furosemide)

Cerebral Aneurysms

•  Uses balloons, coils, or liquid polymer solution to endovascularly treat the aneurysm

•  Usually performed under general anesthesia, a-line should be placed

•  Important to have OR available in case of rupture & urgent need for surgical repair

Central Intraarterial Thrombolysis

•  Treatment of stroke if <6 hrs from onset of symptoms

•  Usually performed under MAC (neurologic assessment is desirable)

Endoscopy & ERCP (Endoscopic Retrograde Cholangiopancreatography)

General Considerations

•  Most upper and lower endoscopies are performed without an anesthesiologist

•  Lateral position for lower endoscopy; lateral/supine for upper endoscopy

•  Important to have access to airway at all times

Technique

•  Anesthetic options range from mild sedation to general anesthesia

• For anesthesia sedation cases: Midazolam/fentanyl/propofol combination often used

•  Patient factors to consider: Pt cooperation, comorbidities, age, mental status, length of procedure

•  Upper endoscopy: Consider pharyngeal topical anesthesia (lidocaine, benzocaine) prior to endoscope insertion

•  Postop pain: Relatively low, usually from air used for inflation

•  ERCP: May be performed in supine, lateral, or prone position; pt can have significant pain during bile duct dilatation