Download Literature review:

Percentage of successful and unsuccessful oral
Sedation for pediatric in MRI unit
BY
RAWAN HESHAM ABDEEN
A project submitted in partial fulfillment of the requirements
for the degree of BSc. In Diagnostic Image Department
Supervised By
Mr. NABEEL MISHA
Faculty of APPLIED MEDICAL SCIENS
KING ABDUL AZIZ UNIVERSITY
6/1429 A.H – 6/2008 A.G
Percentage of successful and unsuccessful oral
Sedation for pediatric in MRI unit
BY
RAWAN HESHAM ABDEEN
We certify that we have read this project and that in
our opinion is fully adequate in scope and quality as
a project for the degree of BSc.
Project supervisor
Mr. Nabeel Misha
2
Percentage of successful and unsuccessful oral
Sedation for pediatric in MRI unit
BY
RAWAN HESHAM ABDEEN
This project has been approved and accepted in partial
fulfillment of the requirements for the degree of BSc.
Dr.Njlah Mustafa
Examiner
Dr. Seddig D. Jastaniah
Head of exam committee
Dr. Sattam Linjawi
Chairmen of diagnostic image
3
Dedicated to my parents who supported and
encouraged me throughout this work.
To my brothers, cousins and my best friend.
4
ACKNOWLEDGMENT
First of all from the bottom of my heart I want to thanks
ALLALH for complete this project and Thanks for every one
who help me to provide this project, thanks for MANAL (MRI
Technologist) who help me and thanks for Dr. MANAL HAKIM
who explain a lot of things to me. Finally, I would like to say
thanks for all my lovely friends in my group ( Abrar, Afnan,
Lamis, Roa'a.b, Roa'a.j, Reem, Shoroog, Sumaya and Walaa) who
help me at all the time.
5
Content:
1- Abstract.
2- Introduction.
3- Literature review.
4- Definition of sedation.
5- Goals of procedural sedation.
6- Indication and contraindication of sedation.
7- Oral sedation (chloral hydrate).
8- Side effect of sedation.
9- Background.
10- Statistical result.
11- Discussion.
12- Recommendation and conclusion.
13- Appendix.
14- Reference.
6
(7 )
(8 )
(9 )
(10)
(14)
(15)
(16)
(18)
(19)
(24)
(25)
(26)
(27)
(42)
Abstract:
Since MRI is very long procedure and noisy sound, the children
can't stay still inside the magnet to the end of the procedure,
so sedation is essential to ensure the quality of exam
performed in MRI. Most of the children below 10 years need to
be given oral sedation to stay stable inside the magnet during
scanning.
ُ‫بالرنين المغناطيسي إجرا ُء طوي ُل جدا ً وله صوت‬
َ‫ فاألطفال ال َيستطيعون‬،‫صاخب‬
ُ
ّ ‫التصوير‬
‫ي لضمان نوعية‬
ُ ‫ لذا التخدير ضرور‬،‫ال َبقاء داخل المغناطيس مستقرين حتى نهاية اإلجراء‬
‫سنَوات َم ْن‬
ّ ‫الفحص المؤدى في التصوير‬
َ 10 ‫ أغلب األطفال تحت‬.‫بالرنين المغناطيسي‬
ّ ‫تخدير عن طريق الفم ل َبقاءهم مستقر‬
.‫ين داخل المغناطيس أثناء التصوير‬
‫الض َُّروري إعطاءهم‬
َ
Objective:
The objective of this research is to identify the percentage of
successful sedations from the first attempts, the percentage
of successful sedations from second dose, and finally the
percentage of unsuccessful sedations in MRI unit.
Importance:
Since there are so many unsuccessful sedations in MRI unit
which reflects negatively on the quality of service and patient
care, this research will facilitate the ability to measure &
compare the effectiveness of our sedation protocols as it is
directly linked to the quality of MRI imaging services.
Motivation:
Sedation and re-sedation is a common problem in each and
every MRI unit and affecting the proper functionality of the
unit by delaying cases in MRI.
7
Introduction:
With its safety and versatility, magnetic resonance imaging (MRI)
should be an ideal modality for body imaging in children. However,
its use is not as universal as expected. Most MRI equipment
manufacturers have not committed adequate resources to produce
hardware and software that are specifically designed to meet the
needs of children. Another problem is the necessity to sedate the
uncooperative young children and infants, often demanding deep
sedation or formal general anesthesia. In the recent few years,
major technical advancements especially the development of
ultrafast imaging techniques and artifact suppression methods, have
led to improvement of image quality and wider applicability. MRI has
become accepted as an important extra-cranial cross-sectional
technique for children in many areas of body imaging, rivaling or
superseding computed tomography (CT) which utilizes ionizing
radiation. (1)
8
Literature review:
MRI has become the imaging modality of choice for many
pathological cases especially in pediatric conditions since it is noninvasive and provides multi-planar imaging ability, high-contrast
images, particularly of the central nervous system (CNS). However,
the image quality can be compromised by patient motion and
cooperation from young children is difficult. Sedation or general
anesthesia is therefore required to keep the patients still inside
the magnet during MRI scanning (2). (To more information see appendix
1)
Infant or child movement during an MR study results in inadequate
signal registration and image degrade, especially at the onset of a
pulse sequence causes image artifact or distortion. This can prolong
the examination, perhaps causing a misdiagnosis because of poor
quality imaging. For this reason, infants and kids are need medicine
to help them sleep so they will lie still during MRI studies (3). The
type of sedation your child needs depends on your child's age and
medical condition some children have a sedative by mouth and
others will receive a general anesthetic. Procedural sedation should
be administered by anesthesia department staff or properly trained
and credentialed NICU clinicians (4). Sedation itself poses safety
risks to infants. Those administering sedatives must carefully
assess and monitor the sedated patient and be prepared to
intervene if patient health condition becomes compromised (5). In
fact, monitoring the sedated infant and kids for potential adverse
events are more challenging in the MR environment than in the
NICU. (To more information see appendix 2).
9
Definition of sedation:
Sedation is the act of lowering the conscious state for purpose of a
procedure or surgery, usually by using drugs called sedative.
Sedation is the use of anesthetics to cause loss of awareness
allowing patients to complete scans safely and comfortably. Infants
and children often need sedation prior to imaging due to an inability
to be still for more than a few moments, affecting the quality of
the scan.
The sedation of children is different from the sedation of adults.
Sedation in children is often administered to control behavior to
allow the safe completion of a procedure. A child’s ability to control
his or her own behavior to cooperate for a procedure depends both
on his or her chronologic and developmental age. Often, children
younger than 6 years and those with developmental delay require
deep levels of sedation to gain control of their behavior (6).
Therefore, the need for deep sedation should be anticipated.
Children in this age group are particularly vulnerable to the sedating
medication’s effects on respiratory drive, patency of the airway,
and protective reflexes (7). For older and cooperative children,
other modalities, such as parental presence, hypnosis, distraction,
10
topical local anesthetics, and guided imagery, may reduce the need
for or the needed depth of pharmacologic sedation. (8,9)
Many people will need to be sedated for MRI technique. It is
critical that sedation be performed safely and by experienced
personnel, but also that it be sufficient for the patient to remain
asleep throughout the entire procedure. Taking mild sedatives
prescribed by a family doctor are almost always inadequate. In fact
many people become more anxious or agitated when they receive
such a medicine. MRI scans infants and young children are often
sedated with an oral medicine called chloral hydrate. Older children
usually need intravenous sedation. Certain people may require an
anesthesiologist to be safely and adequately sedated. Whatever
technique is employed it is important to be sure that the staff at
the scanning facility are thoroughly trained and able to handle any
problems that may arise. This is particularly true for infants and
children (10).
11
Sedation for MRI is usually required for patients who are aged 6
years or less. Occasionally, older children who are mentally retarded
or in an irritated state may also require sedation. It is departmental
policy for children younger than 6 years to be sedated before they
come to the MRI suite. (11) (To more information see appendix 3)
Sedation may be administered by many routes: oral, rectal,
intramuscular or intravenous.(more information see appendix 4). The
recommendation of the American Academy of Pediatrics is that
infants are kept nil per ora (NPO) for at least 4 hours prior to deep
sedation; older children NPO for 6 hours. Sleep deprivation before
the procedure is a good practice. Intravenous line is required to be
set up before sedation. In our hospital, oral choral hydrate (initial
dose of 50mg/kg) is used as first line drug. If oral sedation fails,
intravenous midazolam (Dormican, 0.2mg/kg) is used as second line
drug. (12)
The ideal sedation protocol is one that has an easy route of
administration, with little or no adverse reactions and allows for a
quick, complete recovery. The sedation regimen for each individual
patient is determined (and administered) by the referring
clinicians/pediatricians, based on their own preference and
familiarity with the sedating drugs available.(13)
Sedation can be used for both ventilated and non-ventilated infants
scheduled for MRI. Agents used in infants include chloral hydrate,
fentanyl, and midazolam; (5). A recent Cochrane Neonatal Review
does question the safety of intravenous midazolam in the neonate.
(14) In preterm infants, midazolam can also cause hypotension and a
concomitant drop in middle cerebral artery blood flow velocity.
12
Before administering sedatives or analgesics, appropriate
physiologic monitoring should be initiated, including cardiac,
respiratory, pulse oximetry, noninvasive blood pressure, and endtidal carbon dioxide monitoring for both ventilated and
nonventilated patients (14).Vital signs should be recorded every 5
minutes during procedural sedation of the neonate (15). A sedation
scoring tool, such as the Neonatal Pain, Agitation and Sedation
Scale, can be used to evaluate the infant's level of sedation.(16)
All children undergoing MRI with sedation should not have any risk
factors for aspiration and should not have any illnesses at the time
of the scan. Milk, formula, or solids may be taken up to 6 hours
before the administration of sedatives. Oral medications may be
administered up to the time of sedation. Clear liquids may be taken
up to 2 hours before the administration of sedatives. Children with
a history of gastroesophageal reflux or other GI motility disorders
should have nothing to eat or drink, except for medications, 6 hours
prior to the procedure. (17) (to more information see appendix 5).
13
During sedation monitored is State-of-the-art equipment is used to
monitor blood pressure, heart rate, oxygen saturation, respiration
and exhaled carbon dioxide to ensure patient safety while under
anesthesia. (To more information see appendix 6).
Goals of procedural sedation:
The goals may vary depending on the specific situation.
Nevertheless, an ideal procedural sedation plan often attempts to
achieve the following goals (18):
1. Allay anxiety and fear
2. Obtain cooperation to perform procedure
3. Achieve immobilization
4. Produce unawareness and amnesia
5. Reduce or eliminate pain
6. Keep the child safe during and immediately after sedation
7. Minimizing the residual effects of sedation after the
procedure is over.
14
Indications of sedation:
The most important indication of sedation is for any situation
requiring anxiolysis and analgesia to comfort the child. Also,
sedation potentiates the effect of narcotics, thereby ensuring
better comfort and analgesia. Sedation is a mandatory prerequisite
prior to and during administration of neuromuscular blocker.(19) The
patient should never be subjected to paralysis without sedation. An
additional benefit of sedatives like propofol and benzodiazepines is
that of amnesia and opiates provide analgesia in addition to
sedation.
Contraindication of sedation:
The contra-indications to sedation should be considered in every
case. Monitors should be routinely in place when sedation is applied.
Some clinically relevant contraindications to sedation (20):






conditions with an increased risk of pulmonary aspiration
possibility of airway obstruction or respiratory irregularities
raised intracranial pressure, or other conditions where
increased PaCO2 could be dangerous
conditions where respiratory center is desensitized to carbon
dioxide
renal or hepatic dysfunction, which may alter drug kinetics
Unpredictable drug effect, as sedatives may increase
restlessness.
15
Oral sedation (chloral hydrate):
Chloral hydrate was introduced into medical use by Liebreich in
1869 as the first synthetic sedative-hypnotic. Unlike opioids, it
produces sedation without significant adverse effects on
cardiovascular or respiratory function at therapeutic doses. As
early as 1894, chloral hydrate was being used in children.(21) Despite
the availability of newer agents, chloral hydrate remains a common
choice. In a 2003 survey of pediatric critical care fellowship
training programs in the United States, chloral hydrate was the
seventh most frequently used drug for sedation and analgesia (22).
Chloral hydrate is used principally as an oral/rectal hypnotic in the
treatment of insomnia. It is effective as hypnotic only for short
term use. It may also be used as a routine oral sedative agent. The
drug is used pre-operatively to allay anxiety and produce sedation.
In post operative cases it may be a useful adjunct to opiates and
analgesics. Dosage is the same for oral and rectal administration
and must be individualized for each patient.(23) For children, the
hypnotic dosage of chloral hydrate is 50mg/kg.
Chloral hydrate is most effective in infants and young children one
of the main advantages of chloral hydrate is its lack of associated
respiratory depression. Although rare, the potential for respiratory
depression does exist however, and is most marked when the drug is
16
combined with opioids or other sedatives but has a relatively slow
onset and an unpleasant taste (24). Toxicity can manifest as
gastritis, Skin eruptions or parenchymatous renal damage may
develop following prolonged administration of chloral hydrate.
Prolonged use may also produce tolerance and physical dependence.
Chloral hydrate over dosage produces symptoms which are similar to
those of barbiturate over dosage like coma, hypotension,
hypothermia, respiratory depression and cardiac arrhythmias.
Meiosis, vomiting, a reflexes, muscle flaccidity, esophageal
stricture, gastric necrosis, perforation and gastrointestinal
hemorrhage
have
been
reported.
Treatment of chloral hydrate intoxication consists of general
supportive therapy including maintenance of adequate airway,
assisted respiration, oxygen administration and maintaining body
temperature and circulation. (23)
Chloral hydrate is well established as an agent for sedation in
painless procedures such as diagnostic radiology-usefulness in
painful procedures is limited by patient movement and agitation
even when sedated especially in the young (less than one year old)
child. (to more information see appendix 8).
The ideal pediatric sedating agent must be safe and effective. The
sedation should have rapid onset and recovery, have minimal adverse
effects, and be reversible (25,26). A number of sedation protocols
have been successful. Chloral hydrate administered orally is the
drug used most commonly for pediatric sedation.
17
Side effect of sedation:
The most common side effect of sedation is respiratory depression
manifested by apnea, hypoventilation, or hypoxemia (15). An MRcompatible bag and mask attached to a fixed (wall) oxygen source
should be available for assisted ventilation if the infant becomes
apneic. Standard oxygen tanks should not be brought into the
magnet room. Nonferromagnetic gas cylinders, made of aluminum,
can be purchased for MR room use, but even these should be
tethered to the ground to prevent accidents in the event of an
erroneous cylinder exchange. (27)
To avoid the dangers associated with sedation in infants, an obvious
alternative is to conduct MRI examinations without sedation. Some
centers report success in acquiring a neonatal MRI series without
using sedation. (28) Testing is usually conducted during natural sleep
immediately following a feeding, and careful attention is given to
details such as noise and light reduction, sensor placement to avoid
stimulation, warmth, swaddling, and positioning to minimize
movement(29). Pacifiers are not used because they produce motion
artifact. Obtaining a full MRI series in an unsedated infant usually
takes more time, although administering sedation, managing adverse
sedation reactions, and recovering infants from sedation are time
consuming as well.
18
Background:
As per KAUH policy and procedure all pediatric patients undergoing
MR imaging procedure must be sedated through daycare unit in
order to complete the examination with optimum image quality.
Patient must be admitted to daycare unit early morning on the
appointment day to arrange for sedation. Children should be NPO
for 4 hour prior to sedation procedure. The physician will review the
patient's file and determine the sedation dose according to the
recommended dose for painless procedure that requires
immobilization.
For Neonates at KAUH gives Chloral hydrate 50 mg/kg (PO).
Children < 5 years will be given Chloral hydrate 75 mg/kg (PO) 30
minutes before the procedure + a top-up dose of 25 mg/kg for the
second attempt of sedation for unsuccessful cases.
Children > 5 years will be given Midazolam 0.2 mg/kg (IV) with
additional doses of 0.1 mg/kg at 2 to 3 minutes intervals up to a
maximum of o.5 mg/kg
Or in children with no pre-existing central nervous system
depression give Pentobarbital 2 mg/kg (IV) in 30 second with
further doses titrated against sleepiness up to a maximum of
5 mg/kg.
The physician will make sure that no contraindications are present
for sedation. The nurse will administrate the sedation dose, the
child will be sedated approximately 45 minutes prior to their scan
time, the nurse will wait for the child to fall asleep which varies
from patient to patient. When the child is asleep the nurse will
transport them to the Radiology Department for their scan.
The radiology nurse will enter the sedated patient to MRI room,
then the technologist will position the patient and perform the
exam successfully. The scan will be approximately 45 minutes and
the child's heart rate and oxygen levels will be monitored by one of
the Radiology Nurses.(to more information see appendix 9).
19
In case the patient didn't response to the first dose after 30
minutes from administration then the nurse in daycare will give the
second dose which is the half of the first one under the physician
supervisor then patient will be back the MRI department and the
exam will perform for the sedated patient successfully.
If patient took the maximum dose and didn't get sedated, a result
is the patient will have unsuccessfully MRI exam and should be
arranged for another appointment. If failed again the referring
physician will decide wither to go for general anesthesia or not.
Material and Methods:
I collected the statistical information at KAUH from records
covering the period from 19/4/2008 to 10/5/2008.
The sample group includes 30 infant and children (22 male, 8
female) their age group started from 10 days to 9 years of age
sedated with oral Chloral hydrate. The maximum total dose
administrated was 1.5g of Chloral hydrate which limited the study
to children who weighted 20 kg or less.
20
Statistical information about the successful and
unsuccessful oral sedation for pediatric cases in
MRI unit
Case # …………………
Patient age: ……………
Sex: …………………
Exam name: …………………………………
Type of the sedation: ……………………………………………………
Dose of the sedation:
- First dose:……………………………………………………
- Second dose:………………………………………………
Is there any adverse reaction?
Yes

No

Successful sedation from the first dose

Successful sedation from the second dose
Unsuccessful sedation


Research Conducted by:
Rawan Hesham Abdeen
th
4 year medical technology.
Supervised by:
Mr. Nabeel Mishah.
21
The percentage of successful and unsuccessful oral
sedation for pediatric patient in MRI unit
30
successful
sedation from
1st dose
25
20
20
successful
sedation from
2nd dose
15
10
6
5
4
0
unsuccessful
sedation dose
successful
sedation from
1st dose
13%
20%
67%
successful
sedation from
2nd dose
unsuccessful
sedation dose
22
The percentage of successful sedation from the
second dose for pediatric patient in MRI unit
7
6
successful
sedation
from 2nd
dose
6
5
4
unsuccessful
sedation
fron 2nd
dose
3
2
1
1
0
successful
sedation
from 2nd
dose
14%
unsuccessful
sedation
from 2nd
dose
86%
23
Result:
Sedation with chloral hydrate was successful in 26 of 30 children
which represent (87%) of the total sample group. 20 out of 26
children was successful sedation from the first dose which
represent (67%) of total sample group, 6 out of 26 children was
successful sedation from the second dose which represent (20%) of
total sample group and it was unsuccessful in 4 of 30 children which
represent (13%) of total sample group. While we noticed that the
percentage of adverse reaction resulting from sedation agent is
equal to zero%.
Sedation with second dose of chloral hydrate was successful in 6 of
7 children which represent (86%) of total children which required
to the second dose and it was unsuccessful in 1 of 7 children which
represent (14%) of total children which required to the second
dose.
Comparison to Other Similar Study Results:
By WCW Chu, WWM Lam,
Department of Diagnostic Radiology and Organ Imaging, Prince of
Wales Hospital, Hong Kong
105 patients (87.5%) were successfully sedated compared with 15
(12.5%) who were not. In the successful sedation group, 68 patients
(65%) required the use of only a single agent via the oral,
intravenous, or intramuscular route. Thirty six patients (34%)
required the use of 2 agents and 1 patient (1%) required the use of
3 agents. Twelve patients (12%) had successful, but delayed,
sedation. A total of 82 children were given oral chloral hydrate. Of
these, 44 (54%) were successfully sedated with chloral hydrate
alone, and a further 29(35%) were successfully sedated with an
additional sedation agent. Over 50% of children younger than 8
years were successfully sedated by chloral hydrate alone.
24
Discussion:
Recently, there has been a considerable increase in the number of
diagnostic MRI scans performed in pediatric patients. Most of the
younger children require heavy sedation or general anesthesia to
obtain good images.
Sedation was considered successful if the imaging study was
completed and motion artifacts were minimal or absent. 26 of 30
children were successful to oral chloral hydrate which is represent
the high success rate (87%) of total study group, 20 children was
success directly from the initiate dose with no adverse reaction was
probably to the patient with group age ( 10 days to 3 years ) which
represent (67%)of total study group. This high percentage due to
that the physician is following the policy and procedure for this
group age. So this group age will do the MRI successfully.
7 of 30 children with group age (1 year to 5 years) their response to
sedation agent was delay which required to the second dose. 6 of 30
children was successful sedation from the second dose which
represent (20%) of total study group.
The same sedation agent used for second dose, the only thing is
they decrease the dose by 50% of initiate dose.
The group which was required to the second dose includes 7
children. 6 of 7 children were response to the second dose which
represented (86%) of total sedated children from the second dose
and only 1 of 7 children wasn't response to the second dose which
represented (14%) of total sedated children from the second dose.
The high percentage of response to the second dose will indicate
that is a good technique to give the patient the second dose (half of
initiate dose) to be sedated and the technologist can perform the
MRI examination successfully.
The final group age (5 years to 9 years) include 4 children was
unsuccessfully sedated by oral Chloral hydrate which represent
(13%) of total study group, most of failures occurred in older
children. According to the policy and procedure the older children
25
above 5 years must give them Midazolam 0.2 mg/kg (IV) instead of
Chloral hydrate (PO) to complete the MRI exam successfully.
So because the physician gives this group oral Chloral hydrate not
as per policy and procedure, the children didn't response to it and
the result is unsuccessful oral sedation for this group.
Recommendation:
Due to unsuccessful oral Chloral hydrate sedation for children
above 5 years which will waste the time in MRI unit, the physician
must follow the policy and procedure to give this group age
Midazolam 0.2 mg/kg (IV) with additional doses of 0.1 mg/kg at 2 to
3 minutes intervals up to a maximum of o.5 mg/kg to be sedated
directly and MRI examination can be performed successfully.
Conclusion:
The policy and procedure for pediatric sedation in KAUH have to
follow correctly by the physician to ensure good sedation for
pediatric patient in MRI unit and the rate of unsuccessful sedation
will be minimized.
26
27
Appendix:
1-Magnetic Resonance
Imaging (MRI)
Neurological MRI - Sagittal View
Magnetic resonance imaging
(MRI) is a type of diagnostic
imaging. The MRI machine
scans the brain in “slices” to
produce images. Each image
shows a different “slice” or
level of the brain. They are
also called cross-sectional
images. These images or scans
are
interpreted
by
a
specialized doctor called a
radiologist. Pediatric MRI is a
very useful type of diagnostic
exam and can be used for a
variety of reasons. The sensitivity of MRI to changes in soft tissue,
as well as its very high resolution, allow for the visualization of
changes that may not be seen in other imaging exams, such as an xray or CT scan. An MRI machine does not use ionizing radiation or
X-rays. It generates images based on the amount of water in the
body tissues, using a very strong magnet and radio waves, and a
computer are used to create the pictures. An MRI scan is fairly
noisy but does not hurt. A number of short scans make up a
complete MRI study. Each sequence takes from 1 to 10 minutes. The
total time for a complete MRI study is about 45 minutes. An MRI
can be done on any area of the body (30).
Some MRI scans require the use of a contrast medium, also
referred to as gadolinium. Gadolinium, which is given intravenously,
highlights certain body parts so the radiologist can better see any
abnormalities (31).
28
An MRI (Magnetic Resonance Imaging) scan is used to provide clear
pictures of parts of the body that are surrounded by tissue and
bone. It can also be used to examine joints, the spine and also the
soft organs of your body including the liver, the kidneys and the
spleen. Depending on what part of their body your child is having
scanned, their scan will typically take approximately 45 minutes (32).
The scan is not painful and there are no known dangers or side
effects associated with having an MRI scan and because ionizing
radiation is not used it means the procedure can be repeated
without problems if necessary. Since you will be exposed to a
powerful magnetic field during the scan it is important that you
don't wear any jewelly or have any other metallic objects on your
person (32).
29
Reasons for having an MRI:
MRI is used for imaging many parts of the body. MRI can be used to
evaluate the cause of seizures, developmental delays, headaches,
back pain, and joint injuries. MRI is also frequently used to image
the abdominal and pelvic organs. MRI may be used as a tool to make
an initial diagnosis, or it can be used to follow an existing illness or
injury (31) .
2- Reasons for having sedation during MRI examination:
Child needs to remain very still during the exam. Because of the
size of the equipment and length of the exams, even the most
cooperative kids may have difficulty holding still. Therefore, child
may be given a small dose of short-acting sedation. The medication
is mild enough that the child can be easily aroused. Most children
under the age of 6 years will need to be sedated to complete the
exam. If the child requires sedation, the medical imaging nurse will
administrated the sedation.
Some children require general anesthesia because of certain
medical conditions. General anesthesia is provided to the child by
the pediatric anesthesiologists. The suites are designed to
accommodate the anesthesia equipment within the magnetic
resonance environment (33).
3- Definition of sedation:
Sedation is a continuum of states ranging from Minimal Sedation
through General Anesthesia. Professional organizations have
sedation in different ways According to the American Society of
Anesthesiologists (34).
Sedation means that we give children medicine to help them fall
asleep before the procedure. We also give medicine to relieve pain
when it is needed.
30
Minimal Sedation*: (previously referred to as conscious sedation)
A medically controlled state of depressed consciousness that
- allows protective reflexes to be maintained.
- retains the patient's ability to maintain a patent airway
independently and continuously.
- Permits appropriate response by the patient to physical
stimulation or verbal command e.g., "open your eyes.” Although
cognitive function and coordination may be impaired,
ventilatory and cardiovascular functions are unaffected .
Moderate sedation/analgesia
A drug-induced depression of consciousness during which patients
respond purposefully to verbal commands, either alone or
accompanied by light tactile stimulation. No interventions are
required to maintain a patent airway, and spontaneous ventilation is
adequate. Cardiovascular function is usually maintained.
Deep Sedation
A medically controlled state of depressed consciousness or
unconsciousness from which the patient is not easily aroused.
It may be accompanied by a partial or complete loss of protective
reflexes, and includes the inability to maintain a patent airway
independently and respond purposefully to physical stimulation or
verbal command. Patients may require assistance in maintaining a
patent airway and spontaneous ventilation may be inadequate.
Cardiovascular function is usually maintained.
General Anesthesia
Consists of general anesthesia and spinal or major regional
anesthesia. It does not include local anesthesia. General anesthesia
is a drug-induced loss of consciousness during which patients are
31
not arousable, even by painful stimulation. Patients often require
assistance in maintaining a patent airway, and positive pressure
ventilation may be required because of depressed spontaneous
ventilation or drug-induced depression of neuromuscular function
Cardiovascular function may be impaired (34).
Levels of Sedation (35)
Minimal
Moderate
sedation sedation/analgesia
(Conscious
sedation)
Deep
sedation
General
anesthesia
Responsiveness Normal
Purposeful
Purposeful Unarousable,
response to response to verbal response
even with
verbal
or tactile
following
painful
stimulation stimulation
repeated or stimulus
painful
stimulation
Airway
Unaffected No intervention
Intervention Intervention
required
may
often
be required required
Spontaneous
ventilation
Unaffected Adequate
May be
Frequently
inadequate inadequate
Cardiovascular Unaffected Usually maintained Usually
May be
function
maintained impaired
32
Equipment required for all levels of sedation
(36)
-Positive-pressure oxygen delivery system capable of
administering greater than 90% oxygen at 15 L/minute flow
for at least 60 minutes.
- Appropriate sized masks and oral airways.
- Appropriate drug reversal agents.
- Suction apparatus with suction catheters.
- Monitors capable of measuring oxygenation (pulse
oximeter), blood pressure, heart rate (electrocardiogram or
pulse oximeter), and temperature (thermometer).
- ECG and defibrillator.
- Warming devices.
- Appropriate intravenous equipment.
- Emergency resuscitation equipment.
- Telephone or other device for summoning emergency
assistance.
Main goals of sedation:
Sedation is given to achieve the following goals:
i) To attenuate fear and anxiety.
ii) To potentiate analgesia.
iii) To reduce unnecessary recall (amnesia).
In addition, sedatives are used to reduce metabolic demands
particularly during circulatory shock; to facilitate tolerance to
procedures and as a mandatory adjunct to neuromuscular blockade
(37).
33
4- Routes of sedations:
There are two broad categories of routes commonly used for
sedating a child.
i. Oral/Rectal route
ii. Intravenous (IV) / Intramuscular (IM) route
Oral/Rectal route is best used for premedication before IV
sedation as well as for short painless procedures such as CT scan.
For longer noisy procedures such as MRI with contrast, IV sedation
is invariably required.
IV sedation is delivered by two methods:
a) as a continuous IV infusion, or
b) as intermittent bolus injection.
Continuous IV infusion has the advantage of providing a more stable
level of sedation which is more comfortable for the patient and
more convenient for the nursing staff. However, over sedation can
easily occur if larger amount of drug are cumulatively given. It may
also increase the need for prolonged mechanical ventilation(38).
Bolus injection is usually given in response to patient arousal
therefore less drug may be given over time. However it potentially
exposes the patient to uncomfortable subtherapeutic troughs of
the drug as well as toxic peak levels.
34
5- Prepare Child for Most MRI Exams - Child (Under 6
Years of Age)
Please call the hospital department if you think your child has a
condition that might prevent a MRI exam.
The physician will make sure that no contraindication that might
prevent the MRI exam like(39):
o
o
o
o
o
o
o
o
Pacemaker
Aneurysm clips
Inner ear implants
Bone or neuro stimulations
Metal shavings and / or BB's in your eyes
Permanent eyeliner
Some physical limitations
Recent surgery.
If patient didn't have any contraindication the physician should
check before giving chloral hydrate if patient have any:










heart disease or heart rhythm problems;
ulcer, colitis, or other stomach disorders;
adenoids, sleep apnea, or other breathing disorders;
porphyria;
depression or mental illness;
thoughts of suicide;
a history of drug abuse or dependence;
severe kidney or liver disease.
Raised intracranial pressure.
Neuromuscular disease.
If the child has any of these conditions, the child may not be able
to use chloral hydrate, or the child may need a dosage adjustment
or special tests during treatment (40).
35
Preparation instructions vary by the age of the child:
Having an empty stomach before sedation is very important to your
child's safety.
o
o
o
o
o
o
o
o
Children 2 years of age and older - Do not eat for 8
hours before a MRI exam. Drinking clear liquids is okay
up to 3 hours before the procedure.
Children between age 6 weeks and 2 years - Do not eat
for 6 hours before a MRI exam. Drinking clear liquids is
okay up to 3 hours before the procedure.
Children under 6 weeks and premature newborns - Call
the hospital MRI department for special instructions.
MRI examinations are best performed when children
are sleepy. We recommend keeping your child awake as
late as possible the night the before the test and
waking them very early on the morning of their exam.
For this reason, early Morning appointments are
recommended. Please arrive 30 minutes prior to your
child's scheduled appointment time to register at the
radiology reception desk.
Leave valuables and metal objects at home. MRI
examinations involve very strong magnetic fields.
Remove keys and watches. The magnet can erase the
information on credit cards.
Bring your child's most recent x-ray, CT or MRI scans.
Bring your child's health insurance information and any
necessary forms.
Bring a bottle or snacks for young children to drink /
eat after the examination is complete.
Plan for at least 2 hours to complete the exam. The
length of your child's scan will depend on the type of
procedure, level of sedation and monitoring required.
Very young children (under 6 weeks or premature
newborns) require longer monitoring. This will include an
overnight hospital stay.
36
Most children having MRI scans will be given a needle. Children who
are being sedated or are having a general anesthetic will in most
cases need to get a needle. Some MRI scans give the doctor more
information when they are done with a special liquid called a
contrast medium. This clear, colorless fluid is given to your child
through a small tube or needle inserted into a vein in the hand or
arm (intravenous or IV). The liquid is quite safe. If the radiologist
feels that the child’s scan would be better with this liquid, it will be
given partway through the study (39).
6- Monitoring During MRI
The powerful magnetic field and the generation of radiofrequency
emissions necessitate the use of special equipment to provide
continuous patient monitoring throughout the MRI scanning
procedure. Pulse oximeters capable of continuous function during
scanning should be used in any sedated or restrained pediatric
patient. Thermal injuries can result if appropriate precautions are
not taken; avoid coiling the oximeter wire and place the probe as far
from the magnetic coil as possible to diminish the possibility of
injury. Electrocardiogram monitoring during magnetic resonance
imaging has been associated with thermal injury; special MRIcompatible ECG pads are essential to allow safe monitoring(41-42).
Expired carbon dioxide monitoring is strongly encouraged in this
setting.
7- Drugs for sedation:


Chloral hydrate seems to be very useful and safe when
administered both orally or rectally. We have used it in
children weighing up to 10 kilograms with good effect.
The short acting benzodiazepine midazolam is frequently used
for IV-sedation in adults and children. It appears to have
much greater potential for respiratory depression in the
elderly than in children. It should be used with great caution
together with opioids. It is important to know that its
37

sedative action is also increased when given at the same time
as erythromycin.
Flumazenil is the antidote to benzodiazepines, a competitive
inhibitor in a similar manner like naloxone for opioids. It has
been advised not to use it routinely to "reverse" sedation. It
is good to bear in mind that the effect of flumazenil is
generally shorter than the potential effect of the sedative
drugs. Hence, prolonged observation of the patient is
necessary (43).
8- Chloral hydrate (oral sedation)
This drug may be used effectively in the infant and toddler
population for brief procedures (44). Chloral hydrate may be given
by mouth or per rectum. Onset is within 15 minutes and duration can
be as long as 2 hours. The half-life of the drug is prolonged. This
may necessitate longer observation and may prevent the patient
from safely undergoing sedation within the next 24 hours if
additional studies are needed. Side effects include respiratory
depression and hypoxia. Despite the wide-spread belief that chloral
hydrate is a very safe drug, administration has resulted in a number
of deaths (45,46). One must also remember that no reversal agent
exists for chloral hydrate.
Although chloral hydrate is a safe sedative to use, it has inherent
problems and for this reason, newer drugs may be preferred. When
given orally, there is a delay in its onset of action. This delay is
usually in the range of 15-30 minutes. About 5% of patients may
vomit, resulting in no sedation. In addition, 5% of patients may have
abnormal reaction to the use of chloral hydrate, resulting in a more
excited child than a sedated one. Also, chloral hydrate has been
noted to have significant cardiac side effects, though rare. This
mainly includes cardiac arrhythmias in susceptible patients. In
addition, large studies have noted a 5% decrease in saturation in
the cyanotic patient (47).
38
Pharmacology of chloral hydrate
Chloral hydrate is the first synthetic neurodepressant and was
introduced into therapeutics more than 120 years ago (48). It is
rapidly and extensively metabolized in the liver and erythrocytes by
alcohol dehydrogenase to its major active metabolite,
trichloroethanol, which is thought to be the vital substance in
producing sleep (49). Together with its less active metabolite,
trichloroacetic acid, they are excreted in the urine and bile in free
or conjugated form. However the precise mode of action on the
nervous system remains unknown. The average half-life of
trichloroethanol in adults is 8 hours. The half-life is prolonged in
children (10 hours), preterm neonates (37 hours) and term neonates
(28 hours). Trichloroethanol is 70% to 80% bound to plasma
proteins and is widely distributed to all body tissues including
cerebrospinal fluid, breast milk and placenta. The half life of
trichloroacetic acid is longer, up to 100 hours. It is highly plasma
protein bound (94%), primarily to albumin and may be responsible
for interactions with other highly protein bound drugs. Upon
multiple dosing, due to the prolonged half-lives of the metabolites,
trichloracetic acid can displace bilirubin or warfarin from binding
sites. Its accumulation can cause excessive CNS, respiratory and
vasomotor depression. Therefore monitoring is required during
sedation.
Chloral hydrate is not recommended for use in infants and children
when repetitive dosing would be necessary (50). With repeated
dosing, accumulation of the trichloroethanol and trichloroacetic acid
metabolites may increase the potential for excessive CNS
depression, predispose neonates to conjugated and nonconjugated
hyperbilirubinemia, decrease albumin binding of bilirubin, and
contribute to metabolic acidosis (51).
39
The possible side effects of chloral hydrate:
Get emergency medical help if you have any of these signs of an
allergic reaction: hives; difficulty breathing; swelling of your
face, lips, tongue, or throat.
Call your doctor at once if you have any of these serious side
effects:





uneven heartbeats;
feeling light-headed, fainting;
shallow breathing;
weakness, lack of coordination; or
a red, blistering, peeling skin rash.
Other less serious side effects are more likely to occur, such as:







drowsiness, deep sleep;
headache, or hangover feeling;
nausea, vomiting, indigestion, gas, stomach pain;
redness or drooping of your eyelids;
excitement or confusion;
mild itching or skin rash; or
unpleasant taste in your mouth;
Side effects other than those listed here may also occur. Talk to
your doctor about any side effect that seems unusual or that is
especially bothersome (40).
9-After the scan
Be prepared to stay in the department until your child is fully awake
and has had something to eat and drink. Most families are able to go
home a couple of hours or so afterwards. The nurses will tell you
what sort of sedation your child had in case of later side effects.
The following information should help you care for your child when
you first go home:
40
Children are generally sleepier than usual for 24 hours after an MRI
scan with sedation. This is because the effects of the sedative last
for about a day.
If your child is unduly sleepy or difficult to rouse, make sure he or
she is in a safe position on their side.
Make sure that your child can tolerate a juice drink before offering
anything to eat. Give milk only if your child does not feel sick or
vomit.
Your child may have mood changes which can make him or her
irritable. This is temporary.
Keep a close watch on your child until he or she is back to normal.
Do not leave him or her with an inexperienced carer.
If your child is on any medication, give this as normal (52).
41
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47