MONITORED ANESTHESIA CARE

1. MAC FOR MRI/CT
SCAN
DR TSHERING P. BHUTIA,
SENIOR RESIDENT,
DEPARTMENT OF ANAESTHESIOLOGY ,
SIKKIM MANIPAL INSTITUTE OF MEDICAL
SCIENCE,
GANGTOK,SIKKIM.

2. Special problem of NORA
 Limited working place
 limited access to the patient
 Electrical interference with monitors and
phones, lighting and temperature inadequacy,
 Use of outdated ,old equipment
 Unfamiliar environment that are far removed
from surgical suites.
 Lack of skilled assistant, drugs and supplies.

3. Basic principles for NORA
PATIENT
1. Comorbidity
2. Airway
3. Fasting
status
4. Monitoring
ENVIROMENT
AL
1. Anaesthesia
equipment
2. Emergency
equipment
3. Magnetic/rad
iation
hazards
PROCEDURE
1. Duration
2. Level of
discomfort
3. Patient
position
4. Surgical
support.

4. ASA GUIDELINES
( ASA October 17, 2018)
1. Reliable O2 source with
backup
2. Suction apparatus
3. Waste gas scavenging
4. Adequate monitoring
equipment
5. Safe electrical outlets
6. Adequate
illumination,battery
backup
7. Sufficient space for
anaesthesia
personnel,equipments
8. Emergency
cart,defibrillator,drugs
9. Reliabe means of two-
way communicaton
10. Applicable facility and
safety codes met
11. Appropiate post
anaesthesia
management.

5. Anaphylaxis pack
1. Adrenaline 1:1000 for IM injection
2. Chlorpheniramine
3. Hydrocortisone
4. Blood tubes for tryptase to confirm diagnosis.
5. Readily available clearly displayed
emergency response plans(wall charts)for
cardiovascular collapse,over
sadeation,anaphylaxis.

6. HAZARDS AND SAFETY CONSIDERATIONS
FOR PATIENTS AND STAFF IN THE MRI UNIT

7. 1) A strong magnetic field
 Local heating and may interfere with monitoring
equipment.
 Movement of blood around the body will also
result in the generation of electric potentials and
current causing symptoms such as nausea and
vertigo.
 Current recommendations suggest that an
average exposure of 200mT over any 8-hour
period should not be exceeded by healthcare
personnel.

8. 2) The projectile effect
 All ferromagnetic items must be excluded from
the area of magnet.Eg-O2 tanks,watches,mobile
 All anaesthesia equipment must be compatible
with the magnet in use.
 Patients must be free of implants that could
interact with magnets such as
pacemakers,vascular clips,ICDs,infusion pumps,
cochlear implants,intra-ocular metallic foreign
bodies

9. 3) Implants and foreign bodies
 Implanted ferromagnetic objects may also heat
up significantly during the MR examination
causing local tissue damage-ABSOLUTE
CONTRAINDICATION.
 Most modern patient implants, including metal
prostheses, are non-ferromagnetic.
 General surgical clips, artificial heart valves and
sternal wires are usually deemed safe since they
are fixed by fibrous tissue

10. 4) Equipment and monitoring
issues
 MRI safe or MRI compatible ??
 longer ETCO2 sampling lines
 All alarms should be visual.
 Pulse oximeter cables should be insulated and
placed as far from the scanner as possible.
 Non-invasive blood pressure monitoring is
possible if connectors are changed to plastic.

11. 5) Restricted access of the
environment
 Patient is effectively enclosed within a narrow
tube to which access is extremely limited
 Obese patient may not fit.
 Claustrophobia…..
 Newer designs include open C shaped magnets
that are less claustrophobic.
 Arrangements and backup plan for any critical
incident during MRI should be available.

12. 6) High level acoustic noise
 Noise levels above the safe level of 85 decibels
can be produced during MRI due to the rapid
switching of the gradient coils
 Wearing earplugs to be made mandatory for staff
and patient, whether anaesthetized or not
 Sound alarms to be accompanied with visual
alarms

13. 7)Hazards of MRI during
pregnancy
 The MRI unit may pose hazards to the
developing foetus,including exposure to strong
magnetic fields, high noise levels and
unscavenged anaesthetic gases.
 Currently recommended that pregnant women
should ideally not be scanned during the first
trimester of pregnancy
 Pregnant staff working within the MRI unit should
be advised of the risks.

14. 8) Contrast agents
 Minor side effects including nausea, vomiting and
pain on injection.
 Rare complications called nephrogenic systemic
fibrosis or nephrogenic fibrosing dermopathy, seen
in association with renal impairment
 Anaphylactoid reaction reported.

15. 9) Maintenance of body
temperature
 A theoretical problem during sedation or
anaesthesia of infants and neonates for MRI is
the maintenance of body temperature within this
cooled environment.
 Passive heat loss should be prevented by
minimizing exposure and by returning the infant
to a warm environment as soon as possible
 Radiofrequency radiation produced by the MR
scanner,absorbed by the patient causes an
increase in body temperature, suggesting that
active heating is unnecessary and may in fact

16. Zones in MRI
1. Zone One -accessible to
the general public
2. Zone Two- acts as a
buffer between Zone One
and the more restrictive
Zone Three. Here,
patients are under the
general supervision of
MR personnel
3. Zone Three- should be
restricted by a physical
barrier. Only approved
MR personnel and
questionnaire and
interview are allowed
inside Zone Three.The
MR control room and/or
computer room are
located within Zone Three
4. Zone four-is strictly the
area within the walls of
the MR scanner room,
sometimes called the
magnet room. Access into
the MR scanner room
should only be available
by passing through Zone

18. What is acceptable and what is
not.
 No matter what type or level of anaesthesia care is
provided,an anaesthesia machine should be
present or readily available in all NORA
locations because conversion to general
anaesthesia is always a possibility.
 Adequate prepocedure and postprocedure
space should be available .
 It is certainly the standard of care that an
anaesthesiologist should be available during
recovery period.

19. PREPROCEDURAL
EVALUATION-Additional
considerations.
1. Preprocedure evaluation is a MUST regardless of
where/who is performing the procedure.
2. Assessment of ASA status
3. Factors that may indicate sensitivity to sedation
eg.sleep apnea,COPD,smoking,alcohol
abuse,obesity and renal/hepatic impairment should
be identified.
4. Drug history/allergies
5. Anaesthetic history/airway assessment.
6. Positioning-Patient should be assesed to ensure

20. NPO GUIDELINES
 2HRS-CLEAR FLUID
 4HRS-BREAST MILK
 6HRS-A LIGHT MEAL,INFANT FORMULA,NON
HUMAN MILK
 8HRS-FULL MEAL
 Timely prepocedure evaluation and enforcement of
clear standards for NPO can prevent mishaps and
unnecesary cancelations.
 Educating the proceduralist and their staff is
required.

21.  Consent /Safety checklist
 Preprocedure baseline
parameters(HR,BP,SpO2,RR,Chest)should be
documented.
 Ht/wt measurement-dose calculation.
 Advice on regular medications.
 Reliable IV Cannula
 BEFORE EVERY CASE FORMAL
CONFIRMATION THAT ALL APPROPIATE
EQUIPMENT IS AVAILABLE/WORKING & ITS
LOCATION.

22. Monitoring Considerations
1. ECG
‐rapidly changing magnetic fields produce artifact, ST and
Twave abnormalities, and may mimic arrhythmias,if ECG
wires are in a loop, a the magnetic field may heat the wires
and leads, thus leading to thermal injury (antenna coupling
effect)
2. Pulse oximetry
like ECG wires, the antenna effect may produce thermal injury
3. Capnography
‐increased length of sampling line may have prolonged time
delay
4. Blood pressure
‐need for plastic components
5. Temparature

23. During procedure patient care
 Intravenous(IV)access should be maintained.
 Record of all the drugs given with dose,time &
route.
 Maintain normothermia
 Monitoring vitals should be recorded on a chart.
 Prevent pressure and position related injury
 Patient may be transferred to the recovery area
with same level of care and staffing.
 Proper post procedure orders and time to
discharge should be recorded.

24. Defination of level of sedation
MINIMAL
SEDATION
(ANXIOLYSIS)
MODERATE
SEDATION(CON
SIOUCS
SEDATION)
DEEP
SEDATION
GENERAL
ANAESTHESIA
RESPONSIV
ENESS
NORMAL
RESPONSE TO
VERBAL
STIMULATION
PURPOSEFUL
RESPONSE TO
VERBAL/TACTIL
E STIMULATION
PURPOSEFUL
RESPONSE
TO
REPEATED/PAI
NFUL STIMULI
UNAROUSABL
E EVEN TO
PAINFUL
STIMULI
AIRWAY UNAFFECTED NO
INTERVENTION
REQUIRED
INTERVENTIO
N MAY BE
REQUIRED
INTERVENTIO
N USUALLY
REQUIRED
SPONTANE
OUS
VENTILATIO
N
UNAFFECTED ADEQUATE MAY BE
IMPAIRED/ASI
STANCE MAY
BE REQUIRED
FREQUENTLY
IMPAIRED/ASS
ISTANCE
REQUIRED
CARDIOVAS UNAFFECTED USUALLY USUALLY MAY BE

25. Goals of MAC
1. Maintain patient safety and sense of well
being
2. Alleviate pain and minimize discomfort
3. Minimize psychological response-anxiolysis,
analgesia, amnesia
4. To return to the prepocedural state
5. Safe discharge
6. Drugs should have rapid/complete recovery
7. Minimal nausea and vomiting

26. Drug interactions in MAC
1. No single IV anaesthetic drug can provide all
the components of MAC.
2. Combination of drug act synergistically.eg-
opoid-BZD achieve-
hypnosis,amnesia,analgesia
3. Continous infusion are superior to intermittant
bolus-less fluctuation in drug conc..prompt
recovery.

27. Propofol
1. Short context sensitive half life
2. Doesn’t possess analgesic property-so
LA/opoid
3. Antiemetic property
4. Infusion of 25-50mcg/kg/min
5. Remifentanyl 0.01-0.05mcg/kg/min
6. OR alfentanyl infusion of 0.2-0.4 mcg/kg/min

29. BENZODIAZEPINES
1. Anxiolysis,amnesia,&hypnotic property
2. Midazolam has many advantages over
diazepam.
3. There is often significant and prolonged
psychomotor impairment following conscious
sedation.

30. 30 of 6430 of 64

31. CLONIDINE &
DEXMEDETOMIDINE
 Both are alpha2
agonist.
 Sedative,analgesic and
sympatholytic property
 Dexmedetomidine is
more selective to
alpha2
receptor.alpha1:alpha2
1:1600 as compared to
clonidine which has
selctivity ratio of 1:200
 Shorter half life 2-3hrs
as compared to
clonidine which has12-
24hrs.
 Decreased shivering
 Side effects-
hypotension,bradycardi
a

32. KETAMINE
1. Excellent analgesia
2. Sympathetic property- +effect on
haemodynamic stabiliy
3. Respiratory reflexes intact
4. CNS-bad dreams and hallucinations.
5. Dose-1-2mg/kg(iv)

34. Sedative and protective airway
reflexes
 Complete recovery of swallowing reflex occurs
~15min after return of consciosness from
Propofol anesthesia
 It is depressed for upto 2hrs after midazolam.
 Hypoventilation secondary to opiod-hence
supplemental O2 is required .

35. IT IS IMPORTANT TO REMEMBER THAT
THE SAME BASIC STANDARDS OF
ANAESTHESIA CARE NEED TO BE MET
REGARDLESS OF THE LOCATION.
-THANK YOU.