ANESTHESIA FOR MRI AND CT SCANs .pptx

1. ANESTHESIA FOR MRI AND CT
SCAN
Dr.zikrullah mallick

2. HEADINGS
 Introduction.
 Radiological Suits requiring
Sedation/Anesthesia
 Indications for sedation/Anaesthesia.
 Problems in Radiological suite.
 Types of anaesthesia.
 Anaesthesia for CT.
 Anaesthesia for MRI.
 Practice guidelines for sedation and
anaesthesia.

3. INTRODUCTION
 Anesthesiologists are increasingly being asked to
provide anesthetic care in locations outside of the
OT.
 Key to efficient and safe remote anesthetic depends
on open communication between the
anesthesiologist and non-operating room personnel.
 Because remote locations have different safety
concerns, such as radiation and powerful magnetic
fields

4. Radiological Suits requiring
Sedation/Anesthesia
 Magnetic Resonance imaging(MRI)
 Computed Tomography
 Interventional Neuroradiology
 Ultrasound guided percut. tissue Ablation
 PET Scan/SPECT Scan
 Endoscopy suites
 Cardiac Angiography
 Psychiatric unit for electroconvulsive therapy
 Renal unit for lithotripsy

5. PROCEDURES
 Plain CT
 Contrast CT
 MRI
 MRI Angiography
 Functional MRI

6. Functional MRI
fMRI is the use of MRI to measure the haemodynamic
response related to neural activity in the brain

7. INDICATIONS FOR
SEDATION/ANESTHESIA
 Infants or uncooperative children
 Children or adults with psychological problems
 Children or adults with Movement disorder
 Intubated critically ill patients

8. PROBLEMS IN RADIOLOGY SUITE
Patient
Anesthetist
Environme
nt
Procedure

9. PROBLEM FOR PATIENTS
 Too cold/hot enviornment
 Immobility
 Noise
 Anxiety
 Claustrophobia

10. ENVIORNMENTAL
PROBLEMS
 Dark/Dim light
 Inadequate Space
 Untrained staff
 Cylinder Supply
 Non availability
Drug
Monitors
Equipment
 Lack of Direct observation

11. CHALLENGES FOR
ANESTHESIST
 Developmental delay
 Epilepsy
 Malignancy
 Psychiatric Patient
 CNS disease
 Cardiac
 Respiratory
 Acute trauma with unstable Cardiovascular, Respiratory
or Neurological function

12. CHALLENGES OF
PROCEDURE
 Reaction to iodinated contrast media
 Patient positioning
 Limited access to patient/airway
 Exclusion of ferromagnetic objects in MRI
 Radiation hazard to the Anesthesiologist

13. TYPES OF ANESTHESIA
 Monitoring only
 General Anesthesia
 Using ET Tube and IPPV
 Using LMA
 Conscious Sedation
 TIVA

14. AIMS OF THE
ANAESTHETIST
 Safety of the patient is the overiding goal of
anaesthesia in remote locations and the standard of
care should not differ from that offered in the
operating theatre.
 Rapid recovery from anaestheisa or sedation is
beneficial.
 Anesthetic implications of patient’s medical
conditions do not vary with location

15. ANAESTHESIA FOR CT
 Anaesthetist can remain in the room wearing X-ray protection or
view the patient and monitors from the control room
 The CT scanner does not interfere with monitoring equipment.
 The scans are short and can be interrupted
 The patient couch moves during examination
 Temporarily interruption of ventilation to improve image quality –
immediately re-ventilate
 Patient positioning

16. ANESTHESIA FOR MRI
 MRI has superceded CT for the examination of CNS
and many orthopaedic conditions
 MRI uses a static magnetic field which is
permanently on and super-imposed rapidly
changing magnetic fields and radio-frequency
currents
 Low ionising radiation is used and there are no
known ill effects
 Everyone must be screened before entering
magnetic area and all ferro-magnetic items removed
 MRI can last over an hour and an individual scan
can last upto 20 minutes

17. UNIQUE PROBLEMS OF MRI
 High magnetic field which is always on
 The bore of the magnet is narrow, noisy and
claustrophobic.
 Access to the patient is difficult so airway must be
secured
 Monitoring equipment can introduce stray
radiofrequency current causing degradation of the
image

18. MONITORING
CONSIDERATIONS
 ECG
 Rapidly changing magnetic fields produce artifact, ST
and T wave abnormality…may mimic arrhythmia
 If ECG wires are in loop, the magnetic field may heat the
wires and leads, thus leading to thermal injury (antenna
coupling effect)
 PULSE OXIMETRY
 Like ECG wires, antenna effect may produce thermal
injury
 CAPNOGRAPHY
 BLOOD PRESSURE

19. Equipment for MRI
 Specialized MRI compatible equipment within scan
room or conventional equipment outside scanner
magnetic field
 Non magnetic tipping trolley
 Piped gases, scavenging & suction in both induction
area & control room
 Respiratory gas side stream analyzer with capnograph
with extended sampling line
 MRI compatible pulse oximeter- Fibreoptic patient
probe & shielded cable
 ECG with MRI compatible carbon fibre leads &
electrodes

20. SOLUTIONS…
 MRI compatible anaesthetic equipment or non-MRI
compatible anaesthetic equipment kept outside the
magnetic field
Monitoring during MRI
 To minimize interference, use of Faraday cage and low
band filters
 Capnography:- for monitoring of adequacy of
ventilation and has a disconnection alarm
 Blood pressure-automated blood pressure recording
can be performed using extended cable and nylon
threads on cuff attachment. Invasive blood pressure
measurements need long extension tubing

21. PROBLEMS FOR
ANESTHESIST
 Unfamiliar/outdated Equipments
 Isolated - support services
 No piped gases, no suction
 Moving away from patient
 Difficult to resuscitate

22. The particular goals to consider
when sedating patients
 Guard the patient’s safety and welfare
 Minimize physical discomfort and pain
 Control anxiety, minimize psychological trauma and
maximize the potential for amnesia
 Control movement to allow safe completion of the
procedure
 Return the patient to a state in which safe discharge
from medical supervision is possible.

23. Practice Guidelines for Sedation
and Anesthesia
 Patient must be evaluated before the procedure by
qualified personnel to ensure that patients are not
compromised by coexisting medical conditions
 Appropriate NPO status
 Informed consent
 During the procedure, the level of consciousness,
ventilation, oxygenation, and hemodynamics are to
be evaluated with standard monitors by a designated
individual who should be trained to recognize
complications of analgesia and sedation

24. Practice Guidelines for Sedation
and Anesthesia
 At least one individual trained in basic life support
skills should be present continuously when moderate
or deep sedation is used
 Supplemental oxygen should be used for moderate
and deep sedation, and emergency equipment,
including pharmacologic antagonists, should be
available
 Adequate recovery care should be provided, with the
patient observed in an adequately staffed and
equipped recovery area

25. MRI ZONES

26. PRACTICE ADVISORY ON
ANESTHETIC CARE
 I. Education
 1. MRI education for magnet hazards
 2. MRI education for monitoring limitations
 3. MRI education for long-term health hazards
 II. Screening of Anesthesia Care Providers
and Ancillary Support Personnel
 4. Mandatory screening of all personnel entering
zone III or IV

27.  III. Patient Screening
 5. Patient-related risks for adverse outcomes related
to MRI
 6. Equipment-related risks for adverse outcomes
related to MRI
 IV. Preparation
 7. Planning for the anesthetic care of the patient for
the scan
 8. Planning for rapidly summoning additional
personnel in the event of an emergency

28.  V. Patient Management during MRI
 9. Monitoring during MRI
 10. Anesthetic care during MRI
 11. Airway management during MRI
 VI. Management of Emergencies
 12. Medical emergencies
 13. Environmental emergencies

29.  VII. Post procedure Care
 14. Post procedure care consistent with that
provided for other areas of the institution

30. Sedating agent
 Most children younger than the age of 5 years
and many as old as age 11 require sedation or
general anesthesia to tolerate MRI
 Oral sedation techniques, if appropriately
administered, have a success rate of 93%
 Oral chloral hydrate is a popular agent ( 25-50
mg/kg for infants younger than 4 months, 50
mg/kg for older children)

31.  Benzodiazepines such as midazolam
administered either orally (0.25 to 0.75 mg/kg)
or intravenously (0.05 to 0.15 mg/kg) are also
commonly used for sedation
 Deep sedation with propofol, oxygen
administration via nasal cannula, and end-tidal
carbon dioxide monitoring is a successful
technique

32.  Children are initially sedated with incremental
propofol boluses up to 3 mg/kg with or without
midazolam, 0.03 to 0.05 mg/kg, and then
maintained with an infusion rate of propofol, 1
to 3 mg/kg/hr, with supplemental boluses of 1
mg/kg for movement
 In the case of an emergency , the MRI
technicians should be notified, the scan
sequence stopped, and the patient rapidly
removed

33.  Anaphylaxis to iodinated dyes is possible. All
the drugs for management of anaphylaxis
should always be immediately available
 Resuscitation attempts should take place
outside the scanner because equipment such
as laryngoscopes, oxygen cylinders, and
cardiac defibrillators cannot be taken close to
the magnet

34. SUMMARY
Patient
Environme
nt
Procedure
Anaestheti
st

35. SUMMARY
 These require sedation/Anaesthesia ::
o Infants and uncooperative children.
o People with movement disorders.
o People with psychological disorders.
o Intubated critically ill patients.
 MRI compatible equipment's are required.
 Propofol, Midazolam and Thiopentone are
commonly used.