Transcript ANAESTHESIA FOR NEURORADIOLOGICAL PROCEDURES

ANESTHESIA FOR
NEURORADIOLOGICAL
PROCEDURES
Dr. Adham A.monem Saleh
M.D. Anesthesia, Intensive care,
and Pain management.
Ain Shams University
COMMON NEURORADIOLOGICAL
PROCEDURES
Computed tomography
Magnetic resonance imaging
Functional brain imaging
Positron emission tomography
Interventional neuroradiology
Gamma knife radiosurgery
PATIENTS REQUIRING SEDATION
OR GENERAL ANESTHESIA FOR
NEURORADIOLOGY, WHY?
Anxiety and panic disorders.
 Claustrophobia.
 Developmental delay and learning difficulties.
 Cerebral palsy.
 Seizure disorders.
 Movement disorders.
 Severe pain.
 Acute trauma with unstable cardiovascular,
respiratory, or neurologic function.
 Significant comorbidity.
 Pediatric age group.

SPECIAL CONSIDERATIONS
FOR
ANESTHESIA IN REMOTE AREAS

Senior anesthesiologist is prefered, not a
trainee.

Anesthesia equipment and the imaging
equipment compete for the already narrow
space of the radiology unit.

The anesthesia workstation and the monitors are
usually the oldest in the facility.

Lack of communication between the
anesthesiologist and the radiology staff.

Inadequate preoperative patient preparation.

Considerations for day case anesthesia (patient
selection, anesthetic techniques, recovery and
discharge).
ASA GUIDELINES FOR
ANESTHESIA OUTSIDE
OPERATING ROOM

Reliable Oxygen source (pipelines – cylinders).

Adequate Suction.

Scavenging system (if inhalational agents are used).


Anesthesia machine with equivalent standards to
that in OR and maintained to same standards.
Adequate monitoring equipments to allow
adherence to ASA standards for basic monitoring.




Electrical outlets :
Sufficient for anesthesia machine and monitors.
Adequate illumination :
Battery operated backups.
Sufficient space :
- For personnel and equipments.
- Easy access to patient, anesthesia machine, and the
monitor.
Resuscitation equipment immediately available
:
- CPR equipments.
- Emergency drugs.
- Defibrillator.
MONITORING

Universal standards :
Standard I : requires a qualified anesthesia
personnel to be present in the room throughout the
conduct of anesthesia.
Standard II : continous evaluation of the patient's
oxygenation, ventilation, circulation, and temperature
( ECG - pulse oximetry - capnography - NIBP ).
ANESTHETIC TECHNIQUES


Techniques vary from no anesthesia / minimal or
deep sedation (i.e. MAC) / up to general
anesthesia.
It depends on :

patient’s medical condition.

desired level of anesthesia.

procedure to be performed.

duration of procedure.
DEFINITION OF GA AND LEVELS OF
SEDATION
Minimal
sedation
Moderate
sedation
( anxiolysis )
( previously called
conscious sedation )
Deep sedation
General
anesthesia
Responsiveness
Normal response Purposeful
to verbal
response to
stimulation
verbal or tactile
stimulations
Purposeful
response
following
repeated or
painful
stimulation
Unarousable
even with painful
stimulation
Airway
Unaffected
No intervention
required
Intervention may
be required
Intervention
required
Spontaneous
ventilation
Unaffected
Adequate
May be
inadequate
Frequently
inadequate
Cardiovascular
function
Unaffected
Usually
maintained
Usually
maintained
May be impaired
MONITORED ANESTHESIA CARE
(MAC)

Administration of drugs with anxiolytic, hypnotic,
analgesic, and amnestic properties either alone or in
combination with local or regional anesthesia.
Preoperative assessment :
 Detailed history & examination of the patient (similar
to that done before GA).
+
 Evaluation of ability of the patient to remain
motionless & if necessary actively cooperate
throughout the procedure.
+
 Fasting status.
The following drugs are used in MAC ( SAFE
drugs ):
Propofol

Sedative / hypnotic.

Short half life.

Extra-hepatic clearance.

Rapid & clear headed recovery.

less incidence of post procedural sedation, drowsiness.

Has anti emetic properties (Subhynotic dose of 10
mg is said to be effective ).
Benzodiazepines
Anxiolytic, amnestic, and hypnotic properties.


Midazolam :

Commonly used for moderate to deep sedation.

Short elimination half life (1 to 4hrs).

Dose : 0.02-0.03 up to 0.1 mg/kg IV.
Diazepam :

Longer elimination half life ( > 20 hrs).

active metabolites (desmethyl diazepam, oxazepam).
Opioids
 Provide analgesia component in balanced anesthesia
technique.
 Disadvantage: do not provide amnesia.
Adverse effects
 Respiratory depression.
 muscle rigidity .
 nausea / vomiting.
 Urinary retention (esp. old age).
Sedation / anesthetic drug interaction :
Opioids + benzodiazepines : synergism in hypnotic /
analgesic / amnestic properties.
TYPICAL ADULT INTRAVENOUS RANGES
Drug
Benzodiazepines
Midazolam
Diazepam
Opioid analgesics
Alfentanil
Fentanyl
Remifentanil
Hyponotics
Propofol
Typical adult IV dose range
1-2 mg (0.02 to 0.1 mg/kg)
2.5-10 mg
5-20 µg/kg bolus 2 min. prior to stimulus
0.5-2.0 µg/kg bolus 2-4 min. prior to stimulus
Infusion 0.1 µg/kg/min. 5 min prior to stimulus
Wean to 0.05 µg/kg/min as tolerated
Adjust up or down in increments of 0.025 µg/kg/min
 Dose accordingly when co-administered with midazolam or propofol
Avoid boluses
250-500 µg/kg boluses
25-75 µg/kg/min infusion
Dexmedetomidine Loading dose: 0.1-1 µg/kg over 10-20 min.
Maintenance infusion: 0.2-0.7 up to 1 µg/kg/h
Recommended doses of drugs for sedation in
pediatric patients :
 Chloral hydrate :
50 to 100 mg/kg PO.
 used in healthy infants & children.
 Can produce mild to moderate hypoxia.

Diazepam : 0.1 mg/kg.
 Midazolam :




Morphine :


0.05mg/kg IV.
0.5 mg/kg PO.
0.05-0.1mg/kg IV.
Ketamine :

0.25- 0.5 mg/kg IV , 2-3 mg/kg IM , 5 mg/kg PO.
GENERAL ANESTHESIA TECHNIQUE

Endotracheal intubation & IPPV, or LMA with
spontaneous breathing / IPPV.

Induction of general anesthesia : Propofol /
Thiopentone.

Maintenance of anesthesia : volatile anesthetics /
TIVA.

At the end of procedure patient is transported to
recovery area where further care is provided by
trained anesthesia personnel.
RADIOLOGY SUITE SHOWING NECESSITY FOR
ANESTHESIA EQUIPMENT AND
ANESTHESIOLOGIST TO BE REMOTE FROM
THE PATIENT'S HEAD
SPECIFIC RADIOLOGIC
PROCEDURES
COMPUTED TOMOGRAPHY

CT is a medical imaging method in which an
image of the inside of an object is generated from
a large series of 2D images taken around a
single axis of rotation.

Used for diagnostic or therapeutic purposes.

Hypodense (dark) areas denote infarction.

Hyperdense (bright) areas denote calcification or
hemorrhage.
Problems faced by anesthesiologist :
•
Inaccessibility to patients.
•
Interference with monitoring.
•
In an intubated patient, care should be taken
that sides of scanning tunnel do not dislodge the
circuit.
•
Adverse effects of contrast media.
•
Exposure to ionizing radiation.
Patient monitoring :
 Basic monitoring standards.
 Monitors should be easily viewed.
Anesthetic considerations
Elective
• Preanesthetic visit
on day of the
procedure.
Emergency
• Head injury patients with
ongoing blood loss or
raised ICP.
• Considered full stomach
patients.
• Either scanned awake or
intubated following rapid
sequence induction.
Contrast media :
Contrast media are often used in CT scan.


Types :

Iodinated : hyperosmolar & toxic.

Non iodinated : low osmolarity & fewer side effects.
Adverse effects :

Nephrotoxicity.

idiosyncratic reactions.

anaphylactic/ anaphylactoid reactions.
Contrast related adverse reactions
Adverse reactions
High-osmolarity
contrast media (%)
Low-osmolarity
contrast media (%)
Nausea and vomiting
6.0
1.0
Urticaria
6.0
0.5
Hoarseness, sneezing, cough,
dyspnea, facial edema
2.6
0.5
Hypotension
0.1
0.01


Treatment: usually supportive ttt

O2

Bronchodilators

Corticosteroids

Epinephrine
Patients with past history of reaction to contrast
media

Prednisolone 50 mg IV, 12 h. & 2 h. prior to the procedure.

Antihistaminics immediately before the procedure.
Contrast induced nephropathy :

Acquired ARF.

Incidence is higher with hyperosmolar agents,
especially in dehydrated patients.

For prevention, maintain proper hydration before,
during, and after the procedure.

Usually self limiting & resolves within 2 weeks.

Acetyl Cysteine / Ascorbic acid can be used.


Acetyl cysteine 600 – 1200 mg orally twice daily for 2
days before procedure & 2 days after procedure.
Ascorbic acid 3 gm PO, 2 h before procedure / and 2 gm
twice daily, the day after procedure.
Radiation exposure :

More with CT scan than any other radiological
procedure.


Radiation toxicity :

Somatic effects.

Genetic injury.
Dosimeters: to monitor exposure.

Ionizing Radiation follows Inverse square law.
Radiation exposure decreases proportional to square of
distance from the source.

Radiation exposure is limited by :

lead aprons.

thyroid shields.

using movable leaded glass screens. Anesthesiologist can
stand across the screen & monitor the patient.
MAGNETIC RESONANCE IMAGING

Can differentiate areas of dissimilar anatomy.

Noninvasive.

No ionizing radiation used.

Provides excellent soft tissue contrast.

Can obtain image in any plane.


Differentiates between white & grey matter,
permits resolution of CSF flow.
Disadvantages: Time consuming, patient
movement can produce artifact, Noise > 90db.
CATEGORIES OF PATIENT REQUIRING
ANESTHESIA OR SEDATION IN MRI
Patient Category
Requirement
Pediatric
Sedation / anesthesia
Developmental delay or psychiatric
illness
Education, sedation or anesthesia
Intensive care
Intubation & IPPV
Raised intracranial pressure
Beware of CO2 retention with sedation
CONCERNS IN ANESTHETIC
MANAGEMENT
FOR MRI

Patient accessibility & visibility.

Absolute need to exclude ferromagnetic objects.

Interference / malfunction of equipments caused by
changing magnetic fields.

Potential degradation of images caused by
radiofrequency currents from monitoring
equipments.

Possibility of heat generation within monitoring
Recommendations to prevent thermal injury

Inspection of monitor wires before every use.

Avoid loop formation of monitoring wires,
keeping them straight.

Avoid conductors touching the patient at
more than one location.

To avoid above listed problems , anesthesiologist
must be involved in planning & construction of
MRI suites.
MRI COMPATIBLE MONITORING
EQUIPMENT





ECG: liquid crystal screens, high impedance
graphite electrodes & leads.
Blood pressure: oscillometer with nonferrous
guage.
Respiratory gas: side stream sampling with
long sampling line.
Temperature: skin temperature sensing strips
(burns reported with probes).
Pulse oximeter: non-ferromagnetic model
MRI COMPATIBLE ANESTHETIC
EQUIPMENT





Laryngoscope: plastic scopes with paper or
aluminium covered lithium cells.
Stylet: copper model available.
Endotracheal tube: spring within cuff valve
may distort images; nonmagnetic version is
available, avoid metal reinforced tubes & metal
connectors.
Laryngeal mask airway: spring within cuff
valve may distort images; nonmagnetic version is
available.
Ventilators: compatible versions are available.

Anesthetic machine: nonmagnetic machine,
aluminium cylinders required ( e.g. Aestiva-5 MRI
workstation from Datex Ohmeda).

Infusion pumps: extensions are needed.

Self inflating bags: valveless with no magnetic parts.

Suction: wall mounted with a 10 m tubing.

Defibrillators: resuscitation usually carried out
outside magnetic field (We don’t perform CPR on
MRI table).

Implanted devices or objects representing a
contraindication to MRI :

Cardiac pacemaker.

Some artificial cardiac valves.

Metal eye splinter.

Vascular clips.

Interventional radiology device.

Orthopedic device (prosthetic joint , wires , plates , screws).
ANESTHESIA FOR INTERVENTIONAL
NEURORADIOLOGICAL PROCEDURES
Most commonly :

Occlusive procedures:

Embolization of cerebral & dural AVM.

Coiling of cerebral aneurysms.

Opening procedures:

Thrombolysis of thromboembolic stroke.

Ballon dilatation of vessels.
Vascular access:
Femoral / carotid / brachial artery.
ANESTHETIC GOALS

Maintenance of patient’s immobility.

Physiologic stability.

Manipulation of regional & systemic blood
flow.

Evaluation of coagulation profile.

Treating complications that can occur during
the procedure.

Rapid transition between sedation & awake
responsive state.

Providing brain protecting measures.
ANESTHETIC MANAGEMENT


Pre-procedural anesthetic evaluation, careful
neurologic examination (preexisting deficits
& Glasgow Coma Score).
Airway examination (better to secure airway
early in patients with risk of airway
compromise).

Adequate intravenous access established.

Standard anesthesia monitoring established.

Invasive arterial blood pressure monitoring

Deliberate hypotension

During embolization of AVM - coiling of aneurysm.

Drugs used as esmolol - SNP - labetolol.


Deliberate hypertension

To increase collateral flow to ischemic areas.

Drugs used are phenylephrine - vasopressin.
Urinary catheter: use of large amounts of radiologic contrast
media & osmotic diuretic agents.

Sedation: combination of BZD & opioids.

GA: accomplished by volatile agents or TIVA (considering
desirability of fast emergence for neurologic evaluation).

Padding of pressure points.

Antiemetic can be given.

Heparin is used in some procedures: 70 units/Kg, to
achieve ACT 2-3 times the normal range.

Protamine can be used to reverse heparin effect at the end
of the procedure.

Complications of Liquid embolic agents:
e.g. Cyanoacrylate glue (rapidly polymerizing)

The polymerization process results in heat liberation
into the surrounding tissues during embolization.

Systemic absorption leading to acute hemorrhage and
pulmonary embolism.
COMPLICATIONS OF INTERVENTIONAL
NEURORADIOLOGICAL PROCEDURES
CNS :
 Hemorrhagic
a) aneurysm perforation.
b) intracranial vessel injury.
 Occlusive
a) thromboembolic phenomenon.
b) displacement of coil.
c) vasospasm.
OTHERS :
- Contrast reaction.
- Contrast nephropathy.
- Hemorrhage at puncture site - groin hematoma.
MANAGEMENT OF COMPLICATIONS

Initial resuscitation.

Communicate with radiologist.

Call for help.

Secure the airway & ventilate with 100% O2.

Determine whether problem is hemorrhagic or
occlusive :

If hemorrhagic: immediate heparin reversal, deliberate
hypotension.


If occlusive: delibrate hypertension.
Consider Mannitol , dexamethasone , anticonvulsants.
GAMMA KNIFE RADIOSURGERY


Definition :
Gamma knife radiosurgery is a type of radiation
therapy used to treat tumors and other
abnormalities in the brain (e.g. AVM , Trigeminal
neualgia).
In Gamma knife radiosurgery, specialized
equipment focuses as many as 200 tiny beams of
radiation on a tumor or other target. Although
each beam has very little effect on the brain
tissue it passes through, a strong dose of
radiation is delivered to the site where all the
beams meet.

The accuracy of Gamma knife radiosurgery
results in minimal damage to healthy tissues
surrounding the target and, in some cases, a
lower risk of side effects compared with other
types of radiation therapy. Also, gamma-knife
radiosurgery is often a safer option than
traditional brain surgery.

Gamma knife radiosurgery is usually a one
session therapy completed in a single day.
REFERENCES

Miller’s Anaesthesia, 7th ed.

Wylie and Churchill Davidson’s. 7th ed.

Morgan. Clinical Anaesthesiology, 4th ed.

Barash .Clinical Anaesthesia , 6th ed.



Varma M.K , Price .K , Kessell.G , Manickam.B .Anaesthetic
considerations for interventional neuroradiology .Br J Anaesth
2007;99:75-85
Pannu N,Wiebe N , Tonelli M.prophlaxis strategies for contrast
induced nephropathy. JAMA,June 21, 2006- Vol295,No.23
Practice advisory on anaesthetic care for magnetic resonance
imaging .Anaesthesiology 2009; 110:459 – 79