Literature review: - kau



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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

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

Dedicated to my parents who supported and encouraged me throughout this work.

To my brothers, cousins and my best friend.

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.

Content:

1- Abstract. (7 )

2- Introduction. (8 )

3- Literature review. (9 )

4- Definition of sedation. (10)

5- Goals of procedural sedation. (14)

6- Indication and contraindication of sedation. (15)

7- Oral sedation (chloral hydrate). (16)

8- Side effect of sedation. (18)

9- Background. (19)

10- Statistical result. (24)

11- Discussion. (25)

12- Recommendation and conclusion. (26)

13- Appendix. (27)

14- Reference. (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.

التصوير بالرّنين المغناطيسي إجراءُ طويلُ جداً وله صوتُ صاخبُ، فالأطفال لا يَستطيعونَ البَقاء داخل المغناطيسِ مستقرين حتى نهاية الإجراءِ، لذا التخدير ضروريُ لضمان نوعيةِ الفحص المؤدى في التصوير بالرّنين المغناطيسي. أغلب الأطفالِ تحت 10 سَنَواتِ مَنْ الضَّرُوري إعطاءهم تخديرَ عن طريق الفم لبَقاءهم مستقرينِّ داخل المغناطيسِ أثناء التصوير.

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.

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)

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Literature review:

MRI has become the imaging modality of choice for many pathological cases especially in pediatric conditions since it is non-invasive 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).

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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.

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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, topical local anesthetics, and guided imagery, may reduce the need for or the needed depth of pharmacologic sedation. (8,9)

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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).

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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.

Before administering sedatives or analgesics, appropriate physiologic monitoring should be initiated, including cardiac, respiratory, pulse oximetry, noninvasive blood pressure, and end-tidal 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)

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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).

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).

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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.

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.

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.

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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 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.

Side effect of sedation:

The most common side effect of sedation is respiratory depression manifested by apnea, hypoventilation, or hypoxemia (15). An MR-compatible 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)

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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.

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).

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.

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

4th year medical technology.

Supervised by:

Mr. Nabeel Mishah.

The percentage of successful and unsuccessful oral sedation for pediatric patient in MRI unit

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The percentage of successful sedation from the second dose for pediatric patient in MRI unit

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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.

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 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.

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Appendix:

1-Magnetic Resonance Imaging (MRI)

|Neurological MRI - Sagittal View |

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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 x-ray 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).

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).

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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).

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.

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

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 |Deep sedation |General |

| |sedation |sedation/analgesia | |anesthesia |

| | |(Conscious sedation) | | |

|Responsiveness |Normal response to |Purposeful response to verbal or |Purposeful response |Unarousable, even with |

| |verbal stimulation |tactile stimulation |following repeated or |painful stimulus |

|  |  | |painful stimulation | |

|Airway |Unaffected |No intervention |Intervention may |Intervention |

|  |  |required |be required |often required |

|Spontaneous |Unaffected |Adequate |May be inadequate |Frequently |

|ventilation |  | | |inadequate |

|Cardiovascular |Unaffected |Usually maintained |Usually maintained |May be |

|function |  |  |  |impaired |

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).

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.

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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 Pacemaker

o Aneurysm clips

o Inner ear implants

o Bone or neuro stimulations

o Metal shavings and / or BB's in your eyes

o Permanent eyeliner

o Some physical limitations

o 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).

Preparation instructions vary by the age of the child:

Having an empty stomach before sedation is very important to your child's safety.

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.

o 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.

o Children under 6 weeks and premature newborns - Call the hospital MRI department for special instructions.

o 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.

o 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.

o Bring your child's most recent x-ray, CT or MRI scans. Bring your child's health insurance information and any necessary forms.

o Bring a bottle or snacks for young children to drink / eat after the examination is complete.

o 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.

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).

Monitoring During MRI 6-

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 MRI-compatible 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 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).

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).

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:

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).

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52- .

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