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Anaesthesia or sedation for MR

I in childrenLeonie Schulte-Uentrop and Matthias S. Goepfert

Department of Anaesthesiology, University MedicalCenter Hamburg-Eppendorf, Hamburg, Germany

Correspondence to Leonie Schulte-Uentrop,Department of Anaesthesiology, University MedicalCenter Hamburg-Eppendorf, Martinistrasse 52, 20246Hamburg, GermanyTel: +49 40 15222816109;e-mail: lschulte@uke.uni-hamburg.de

Current Opinion in Anaesthesiology 2010,23:513–517

Purpose of review

The purpose of this review is to focus on recent literature about sedation or anaesthesia

in paediatric MRI. Special features of the MRI working environment, recent studies

about sedation or anaesthesia, and success rates and risk profiles in this setting are

presented. Finally, information for physicians to decide between sedation or

anaesthesia in individual situations is presented.

Recent findings

Owing to advances in MRI and its crucial role in the diagnosis of various diseases, deep

sedation or anaesthesia for MRI in children is requested increasingly. According to

current guidelines maximum patient safety and welfare has to be ensured. Recently

different sedation regimens comparing effectiveness, safety and outcome have been

published. Chloral hydrate, pentobarbital and midazolam are unfavourable for MRI

sedation. Dexmedetomidine appears to be convenient for sedation in patients without

cardiac risk. Propofol can be effectively used for sedation or anaesthesia in the

presence of anaesthesiologists or paediatric intensivists. General anaesthesia should

be preferred in preterm or small children as safety and success are predictable.

Summary

The MRI unit is a work station where all processes have to be well planned and staff

trained to guarantee maximum patient safety, superior quality of imaging and economic

needs. For optimal performance trained, experienced and certified personnel,

appropriate drugs for the individual patient risk profile and sufficient monitoring

equipment are essential.

Keywords

anaesthesia, MRI, paediatric, sedation

Curr Opin Anaesthesiol 23:513–517� 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins0952-7907

Introduction

MRI is a noninvasive, radiation-free diagnostic procedure.

A magnetic field with strength of 1.5–7 T (140 000 times

the Earth’s natural magnetic field) is used to perform MRI

clinically. These magnetic forces orient all protons in the

magnetic field in a longitudinal direction and create a spin.

A high-frequency radio impulse is then applied with the

same frequency as the spin. This triggers the protons to

absorb energy. After stopping the radio frequency, the

protons return to their initial position and emit radio waves

that serve as raw material for the MRI [1�,2].

Depending on the diagnostic needs an MRI scan takes

about 10–30 min, is quite noisy and the patient is moved

into a narrow pipe with limited access. For optimum image

quality enabling precise diagnosis patients have to remain

motionless. Metallic materials have to be removed as they

impair image quality and may induce undesirable side

effects, e.g. warming. The high-frequency radio impulses

can cause damage to or dysfunction of medical devices. For

this reason an anaesthesia workstation in an MRI environ-

ment has to fulfil specific criteria to meet the highly

opyright © Lippincott Williams & Wilkins. Unauth

0952-7907 � 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins

specialized respective needs. Nevertheless, it also has to

perform as any other anaesthesia unit with a ventilator,

anaesthetic gas measurement, capnography, pulse oxime-

try, ECG monitor, blood pressure measurement and respir-

atory frequency monitor.

For paediatric anaesthesia, the ventilator in the MRI

setting has to be equipped with compliance compen-

sation, and resuscitation material has to be within reach.

Finally it must be pointed out that an MRI emergency

stop takes some minutes to be effective and is expensive.

The frequency of MRI scans in children has increased in

recent years owing to significant improvements in MRI

opening up new diagnostic perspectives [3]. If young

patients are unable to cooperate or to be at rest, either

sedation or anaesthesia is required. Most children who

need MRI diagnostic procedures have neurological dis-

eases, vascular malformation or oncological tumour

growth. Epilepsy and spastic or mental retardation are

common symptoms in these patients [4,5��]. These facts

must be taken into account when sedation or anaesthesia

for MRI in children is required. In the end, however, the

orized reproduction of this article is prohibited.

DOI:10.1097/ACO.0b013e32833bb524

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514 Anesthesia outside the operating room

main goals to be achieved are maximum patient safety,

successful scanning and paramount image quality.

Sedation for MRIUsually the Observer’s Assessment of Alertness and

Sedation (OAAS) scale or the Ramsey score are used to

describe sedation depth clinically [6]. For children the

American Academy of Pediatrics defined four sedation

steps: anxiolysis, conscious sedation, deep sedation and

anaesthesia [7]. Goals of sedation in the paediatric patient

for diagnostic and therapeutic procedures are defined as:

guard the patient’s safety and welfare; minimize physical

discomfort and pain; control anxiety, minimize psycho-

logical trauma, and maximize the potential for amnesia;

control behaviour and/or movement to allow the safe

completion of the procedure; and return the patient to a

state in which safe discharge from medical supervision, as

determined by recognized criteria, is possible. These goals

can be achieved by selecting the lowest dose of one drug

with the highest therapeutic index for the procedure.

Concerning children and MRI, because of noise and tube

narrowness, deep sedation is the required depth for

examination in most cases. Stopping an MRI scan is

expensive and ineffective, thus the failure rate has to

be minimized.

Prerequisites for sedation are the same as for general

anaesthesia: fasting, intravenous access, vital signs

monitoring, emergency equipment and physicians who

are experienced in using the technical equipment and

trained in paediatric airway management.

In this context it must be pointed out that disabled

children do not need higher doses of sedatives but are

three times more at risk of hypoxia under sedation [5��].

As the view of and access to the patient are limited in the

MRI setting, the physician has to be very experienced in

paediatric medication and airway management in new-

borns and children. If hypoventilation occurs, stopping

the scan, pulling the scan desk outside the tube and

attending to the patient in this special surrounding is time

consuming and needs to be practised. In newborns and

infants immediately after oxygen desaturation occurs

bradycardia starts. This has to be kept in mind when

choosing a suitable procedure and monitoring for our

paediatric patients.

A very safe and simple technique for newborns is the

‘feed and scan’ technique in which children are fed and

one has to wait until the young patient falls asleep.

Remarkable disadvantages of this technique are the

unpredictable ‘induction times’ and the high failure rates

of the scanning procedure. This time-consuming pro-

cedure therefore seems not to be practicable in most

opyright © Lippincott Williams & Wilkins. Unautho

modern medical centres. In 2008 Beauve and colleagues

compared the feed and scan technique with moderate

chloral hydrate sedation in neonates. The MRI failure

rate was similar, but the time until MRI was started was

shorter for chloral hydrate sedation [8]. As still only a few

studies exist on the exact mode of action of different

sedative drugs in paediatric patients and off-label use has

to be performed in many cases the feed and scan tech-

nique has to be considered as a relevant alternative [9].

In another investigation melatonin was used for sleep

induction before MRI. The success of this sleep induc-

tion concept was not convincing. Nevertheless high doses

of this substance combined with sleep withdrawal might

have an effect but needs further proof [10,11].

Who should perform sedation, a physician or a specially

trained nurse? In most countries in Europe and overseas,

anaesthesiologists are responsible or indispensable owing

to regulatory frameworks. In the UK or France, however,

sedation is also provided by trained nurses. This topic has

been discussed controversially [12]. Krauss et al. [13]

described the advantages and disadvantages of the US

model, which has helped to make sedation and analgesia

significantly safer and more professional than procedures

performed 20 years ago in the United States.

The Paediatric Sedation Research Consortium recently

reported on 49 836 sedation or anaesthesia cases involving

propofol over a 3-year period. Two cardiac arrests, four

aspiration events, and no deaths were among this cohort.

One in 65 sedations was associated with stridor or lar-

yngospasm or airway obstruction or expiratory wheezing

or central apnea [14��].

In this context it has to be pointed out that chest excursions

cannot be observed easily and saturation might fall late

after cessation of breathing, particularly if oxygen is insuf-

flated. For this reason end-tidal CO2 monitoring is indis-

pensable in MRI sedation and anaesthesia procedures.

Long-distance ventilator or capnometry tubes are often

used in the MRI setting. Therefore there are significant

drawbacks in using these devices. Another alternative to

measure respiratory excursions is a special respiratory belt

that monitors chest excursions during MRI scanning.

There is a variety of drugs available for sedation. Which

of these substances are favourable for MRI sedation?

When choosing an adequate sedative for MRI in children

the review of Krauss et al. [15] about procedural sedation

and analgesia is helpful.

Chloral hydrateChloral hydrate is a sedative and hypnotic drug with

barbiturate-like features. Onset time if applied orally is

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Anaesthesia or sedation for MRI in children Schulte-Uentrop and Goepfert 515

15–30 min, and duration is 60–120 min. If given in thera-

peutic doses it has only a slight effect on ventilation and

blood pressure, but its therapeutic index is small. Dosing

is between 25 and 100 mg/kg [15].

A recent review analysed chloral hydrate sedations

in term and preterm infants. The occurrence of post-

procedural oxyhaemoglobin desaturation was directly

correlated with younger chronological age in term infants

and younger postconceptional age in preterm infants

[16��].

Cortellazzi et al. [17] reported on 1104 chloral hydrate

sedations. In 20% MRI scan could not be finished suc-

cessfully, airway obstruction was seen in 2.8%, oxygen

saturation<90% occurred in 0.4%; no assisted ventilation

was necessary [17]. Low et al. [18] examined 36 children

aged<1 year when oral chloral hydrate was used for MRI

sedation. The success rate for MRI was 86%. No respir-

atory complications occurred [18].

In conclusion chloral hydrate seems to be a safe sedative,

but its side effects such as nausea and vomiting, long

recovery times and postoperative agitation have to be

considered. High failure rates of successful MRI scanning

could not prove this substance to be cost effective and

time saving in this context.

PentobarbitalPentobarbital is a short-acting barbiturate. Its reputation

has suffered as it was involved in euthanasia discussions.

Oral or rectal dosing is 3–6 mg/kg. Time until onset of

sedation is 15–60 min, and duration is 60–240 min [15].

Rooks et al. [19] compared pentobarbital and chloral

hydrate sedation for MRI in 498 children. No relevant

differences were observed between the groups. In further

studies pentobarbital showed a better acceptance by

children and parents [20], fewer adverse events [21]

but more paradoxical reactions and motion artefacts

[22] than those in the chloral hydrate group. When using

pentobarbital, potential relevant cardiovascular and

respiratory depression and the contraindications in

patients with porphyria have to be considered.

KetamineKetamine is commonly ignored as a sedative for MRI as it

has an analgesic component which is not necessary for

MRI. Dosing is 1–1.5 mg/kg when applied intravenously

or 4–5 mg/kg when injected intramuscularly. Onset time

is 1–3 min, and duration is 15–30 min [15].

In 2009 Green et al. [23��] reviewed the airway and

respiratory adverse events when ketamine was used as

opyright © Lippincott Williams & Wilkins. Unauth

sedative. In 8282 cases an overall risk of airway problems

for ketamine of 3.9% was reported. Risk factors for these

problems were age below 2 and over 13 years, high

intravenous dosing, coadministration of anticholinergics

or benzodiazepines [23��].

Vardy et al. [24] compared ketamine with midazolam and

propofol for procedural sedation. In this investigation

there was a similar overall complication rate, but in the

case of ketamine more hypertonicity, hypertension and

re-emerge phenomena occurred [24]. This characterizes

the special attribute of this drug that distinguishes it from

most other sedatives. In conclusion, ketamine used alone

may be useful for sedation in patients with respiratory

risk factors.

MidazolamMidazolam used alone is not suitable for MRI sedation

as its duration is too short for a successful procedure of

20–30 min. It has to be either re-injected or used in

combination with fentanyl or pentobarbital or ketamine.

As shown in the review by Green et al. [23��] the com-

bination of sedatives is a risk factor for respiratory com-

plications.

Combined sedation drug use in children is not acceptable

because the effects are hardly predictable and therefore

risky.

PropofolPropofol seems to be a perfect drug for sedation because

it is effective, has a short recovery time and can easily be

titrated to the required sedation level. Dosing is normally

2–5 mg/kg/h intravenous. Machata et al. [25] observed 53

infants and 447 children for an ambulatory MRI pro-

cedure. In 1% mild respiratory complications occurred

(no intubation). Short induction and a recovery time of

8 min are convincing advantages of propofol use [25].

Dalal [26] compared chloral hydrate and pentobarbital

with propofol for MRI sedation use. In this investigation

propofol was associated with shortest ready to scan and

discharge times. But in 13.6% cardiorespiratory events

were reported [26]. Patel et al. [27] evaluated the success

and dosing requirements of propofol in children for

prolonged procedural sedation by a nonanaesthesiol-

ogy-based sedation service. Two hundred and forty-nine

patients with a mean age of 4.8 years were included. All

sedations were successful and unanticipated adverse

effects rare (<1%) [2].

When using propofol only for sedation purposes the low

therapeutic tolerance has to be stressed. Consequently the

physician must monitor the respiratory rate and manage

the paediatric airway. Under these circumstances, propofol

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516 Anesthesia outside the operating room

can be used to provide comfortable and adequate sedation

for MRI scanning.

DexmedetomidineDexmedetomidine is a selective alpha-2 agonist which is

declared by the ASA to be sedative which can be used by

nonanaesthesiologists. No relevant respiratory effects of

this drug are known. Haemodynamic side-effects such as

low blood pressure and low heart rate are common.

A loading dose of 2–3 mg/kg over 10 min followed by

1–2 mg/kg/h as an infusion for sedation maintenance is

recommended. Life-threatening complications have to

be expected if dexmedetomidine is used in combination

with digoxin [28,29]. Because of these side-effects the

drug is not suitable for patients with cardiac compromise.

Several studies investigating dexmedetomidine for seda-

tion have been published recently. Mason and colleagues

[30] reported MRI procedures for 747 children and

showed successful imaging in 97.6%. Cardiovascular si-

de-effects (bradycardia never exceeding a 20% range

from standard values) were seen in 16%. Oxygen satur-

ation was always above 95% [30]. In children with

obstructive sleep apnoea syndrome a comparison

between dexmedetomidine and propofol for MRI sleep

induction revealed effective sedation without the need

for additional airway equipment in 88.5 versus 70% of

scans [31��]. Some other investigations found no differ-

ence in successful scanning between dexmedetomidine

and propofol in 60 children between 1 and 7 years old but

propofol showed advantages in induction, recovery and

discharge time. No oxygen desaturation was seen in the

dexmetedomidine-sedated children [32]. Similar results

were reported by Heard and collegues [33], who com-

pared a midazolam–dexmedetomidine combination with

propofol for sedation. Lubisch et al. [34] published a

retrospective study of children with autism and other

neurobehavioural disorders. Three hundred and fifteen

patients with a mean age of 3.9 years were sedated with

dexmedetomidine, most commonly for MRI, while 90%

of patients received concomitant midazolam. Seven

patients required intervention for cardiac events and

one for a respiratory event. There were two episodes

of recovery-related agitation; 98.7% of sedations were

successfully completed [34].

In summary, dexmedetomidine could, if one takes

account of the contraindication of cardiovascular comor-

bidity, be a favourable sedative drug for MRI scanning.

Anaesthesia for MRIAn apparent advantage of general anaesthesia for MRI

scanning is that it is independent of a child’s ability to

cooperate. The whole process, including preparation and

scan time, is more predictable, and the scan quality may

opyright © Lippincott Williams & Wilkins. Unautho

benefit because the child is immobilized and scan inter-

ruptions due to sedation side-effects are minimized.

In addition, it is possible to perform breath-holding

manoeuvres for images that need complete immobiliz-

ation. Anaesthesia is an effective and quality-guarantee-

ing method in this setting [35]. In newborns and infants at

risk from very short times of respiratory insufficiency due

to hypoxia and bradycardia general anaesthesia should be

performed for safety reasons.

In principle all types of general anaesthesia techniques

can be used in MRI. If the ventilator is equipped with a

vaporizer, sevoflurane is an ideal inhalative narcotic for

children. On the other hand, propofol can be used for

total intravenous anaesthesia. Laryngeal masks and

tracheal tubes can be used in the MRI setting. The

decision should depend on comorbidities, anatomy and

fasting status in the individual case.

In a group of 200 children with neurodevelopmental

disorders and comedication with anticonvulsive and psy-

chotropic drugs sevoflurane was compared with propofol

for successful MRI procedures. In the sevoflurane group a

92% scan success rate was achieved compared with an

80% success rate in the propofol group. No difference in

respiratory complications was noted [36�].

Compared with propofol sedation using this drug as a

narcotic in combination with tracheal intubation, atelec-

tasis was seen more often in intubated children after the

MRI scan. In 26 young patients at the end of anaesthesia

the difference in the atelectasis rate was 82–94%. Atelec-

tasis had already occurred in the early stage of scanning

in intubated children and in those who were ventilated

with intermittent positive-pressure ventilation [37,38].

ConclusionAnaesthesia or sedation for MRI procedures in children is

the question we help to answer here. It is obvious that the

decision has to be made on a case-by-case basis, taking

into account all characteristics of the individual child.

A fully equipped anaesthesia workstation is strictly

required for both sedation and anaesthesia. Airway

management and resuscitation equipment have to be

prepared and directly available. Adequate training in

paediatric airway and emergency management in this

setting with a restricted view of and access to the patient

is essential for anaesthesiologists or paediatric ICU

physicians. As drug permission is variable in different

countries, off-label use is performed in some situations.

In children older than 3 years or with a body weight of

more than 10 kg sedation might be a safe alternative to

anaesthesia if no specific airway abnormalities or comor-

bidities are present. In infants younger than 3 years or in

the presence of major comorbidities that may aggravate

rized reproduction of this article is prohibited.

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Anaesthesia or sedation for MRI in children Schulte-Uentrop and Goepfert 517

airway management or the clinical procedure, general

anaesthesia is the preferred choice and implies a pre-

dictable clinical process.

AcknowledgementThe authors affirm that there does not exist any conflict of interestor sponsorship.

References and recommended readingPapers of particular interest, published within the annual period of review, havebeen highlighted as:� of special interest�� of outstanding interest

Additional references related to this topic can also be found in the CurrentWorld Literature section in this issue (p. 537).

1

�Bryson E, Frost EAM. Anesthesia in remote locations: radiology and beyond,international anesthesiology clinics CT and MRI. Int Anesthesiol Clin 2009;47:11–19.

Describes the characteristics of anaesthesia in radiology units.

2 Paczynski S, Braun KP, Muller-Forell W, Werner C. Fallgruben in der magne-tresonanztomographie. Anaesthesist 2007; 56:797–804.

3 MacManus B. Editorial. Trained nurses can provide safe and effective seda-tion of MRI in pediatric patients. Can J Anesth 2000; 47:197–200.

4 Funk W, Hoerauf K, Held P, Taeger K. Anasthesie zur Magnetresonanztomo-graphie bei Neonaten, Sauglingen und Kleinkindern. Radiologe 1997; 37:159–164.

5

��Kannikeswaran N, Mahajan P, Sethurman U, et al. Sedation medication receivedand adverse events related to sedation for brain MRI in children with and withoutdevelopmentally disabilities. Paediatr Anaesth 2009; 19:250–256.

A review about adverse events in sedation for MRI in disabled children. Shows thatdevelopmentally disabled children have similar requirements for sedative drugs,but are more likely to experience hypoxia

6 Schmidt GN, Mueller J, Bischoff P. Messung der Narkosetiefe. Anaesthesist2008; 57:9–36.

7 American Academy of Pediatrics, American Academy of Pediatric Dentistry,Charles J. Cote, Stephen Wilson the Work Group on Sedation. Guidelines formonitoring and management of paediatric patients during and after sedationfor diagnostic and therapeutic procedures: an update. Pediatrics 2006;118:2587–2602.

8 Beauve B, Dearlove O. Sedation of children under 4 weeks of age for MRIexamination. Paediatr Anaesth 2008; 18:892–893.

9 Anand KJS, Hall RW. Pharmacological therapy for analgesia and sedation inthe Newborn. Arch Dis Child Fetal Neonatal Ed 2006; 91:F448–F453.

10 Sury MRJ, Fairweather K. The effect of melatonin on sedation of childrenundergoing magnetic resonance imaging. Br J Anaesth 2006; 97:220–225.

11 Wassmer E, Fogarty M, Page A, et al. Melatonin as a sedation substitute fordiagnostic procedures: MRI and EEG. Dev Med Child Neurol 2001; 43:136.

12 Hertzog JH, Havidich JE. Nonanaesthesiologists-provided pediatric proce-dural sedation: an update. Curr Opin Anaesthesiol 2007; 20:365–372.

13 Krauss B, Green SM. Training and credentialing in procedural sedation andanalgesia in children: lessons from the United States model. Paediatr Anaesth2008; 18:30–35.

14

��Cravero JP. The incidence and nature of adverse events during pediatricsedation/anesthesia with propofol for procedures outside the operating room:a report from the Pediatric Sedation Research Consortium. Paediatr Anesthe-siol 2009; 108:795–804.

Review of a large database of prospectively collected data on sedations withpropofol outside the operating room. It indicates that sedation or anaesthesia withpropofol is unlikely to yield serious adverse outcomes in a collection of institutionswith highly motivated and organized sedation or anaesthesia services.

15 Krauss B, Green SM. Procedural sedation and analgesia in children. Lancet2006; 367:766–780.

16

��Litman R, Soin K, Salam A. Chloral hydrate sedation in term and preterm infants:an analysis of efficacy and complications. Anesth Analg 2010; 3:739–746.

A study that analyses chloral hydrate sedations in infants and showed that theoccurrence of postprocedural desaturation was correlated with younger age interm infants and younger postconceptional age in preterm infants.

opyright © Lippincott Williams & Wilkins. Unauth

17 Cortellazzi P, Lamperti M, Minati L, et al. Sedation of neurologically impairedchildren undergoing MRI: a sequential approach. Paediatr Anaesth 2007;17:630–636.

18 Low E, O’Driscoll M, MacEneaney P, O’Mahony O. Sedation with oral chloralhydrate in children undergoing MRI scanning. Ir Med J 2008; 101:80–82.

19 Rooks V, Chung T, Connor L, et al. Comparison of oral pentobarbital sodium(Nembutal) and oral chloral hydrate for sedation of infants during radiologicimaging: preliminary results. Am J Roentgenol 2003; 180:1125–1128.

20 Chung T, Hoffer FA, Connor L, et al. The use of oral pentobarbital sodium(Nembutal) versus oral chloral hydrate in infants undergoing CT and MRimaging: a pilot study. Pediatr Radiol 2000; 30:332–335.

21 Mason KP, Sanborn P, Zurakowski D, et al. Superiority of pentobarbital versuschloral hydrate for sedation in infants during imaging. Radiology 2004;230:537–542.

22 Malviya S, Voepel-Lewis T, Tait A, et al. Pentobarbital vs chloral hydrate forsedation of children undergoing MRI: efficacy and recovery characteristics.Paediatr Anaesth 2004; 14:589–595.

23

��Green SM, Roback MG, Krauss B, et al. Predictors of airway and respiratoryadverse events with ketamine sedation in the emergency department: anindividual-patient data meta-analysis of 8282 children. Ann Emerg Med 2009;54:171–180.

An interesting review of former studies with ketamine sedation. Shows that the riskof airway problems for ketamine is more frequent in children<2 and>13 years old.

24 Vardy JM, Dignon N, Mukherjee N, et al. Audit of the safety and effectivenessof ketamine for procedural sedation in the emergency department. EmergMed J 2008; 25:579–582.

25 Machata A, Willschke H, Kabon B, et al. Propofol-based sedation regimen forinfants and children undergoing ambulatory magnetic resonance imaging. Br JAnaesth 2008; 101:239–243.

26 Dalal P. Sedation and anesthesia protocols used for magnetic resonanceimaging studies in infants: provider and pharmacologic considerations.Anesth Analg 2006; 103:863–868.

27 Patel KN, Simon HK, Stockwell CA, et al. Pediatric procedural sedation bya dedicated nonanesthesiology pediatric sedation service using propofol.Pediatr Emerg Care 2009; 25:133–138.

28 Ingersoll-Weng E, Manecke GR Jr, Thistlethwaite PA. Dexmedetomidine andcardiac arrest. Anesthesiology 2004; 100:738–739.

29 Berkenbosch JW, Tobias JD. Development of bradycardia during sedationwith dexmedetomidine in an infant concurrently receiving digoxin. Pediatr CritCare Med 2003; 4:203–205.

30 Mason K, Zurakowski D, Zgleszewski S, et al. High dose dexmedetomidine asthe sole sedative for pediatric MRI. Paediatr Anaesth 2008; 18:403–411.

31

��Mahmoud M, Gunter J, Donnelly L, et al. A comparison of dexmedetomidinewith propofol for magnetic resonance imaging sleep studies in children.Anesth Analg 2009; 109:745–753.

In this interesting sleep study 82 children with obstructive sleep apnoea wereexamined by MRI with sedation. The need for an artificial airway was significantlyless with dexmedetomidine than with propofol.

32 Koroglu A, Teksan A, Sagir O, et al. Comparison of the sedative, hemody-namic, and respiratory effects of dexmedetomidine and propofol in childrenundergoing magnetic resonance imaging. Anesth Analg 2006; 103:63–67.

33 Heard C. A comparison of dexmedetomidine–midazolam with propofol formaintenance of anesthesia in children undergoing magnetic resonanceimaging. Paediatr Anesthesiol 2008; 107:1832–1839.

34 Lubisch N, Roskos R, Berkenbosch JW. Dexmedetomidine for proceduralsedation in children with autism and other behaviour disorders. Pediatr Neurol2009; 41:88–94.

35 Allen JG, Sury M. Sedation of children undergoing magnetic resonanceimaging. Br J Anaesth 2007; 98:548–549.

36

�Bryan Y, Hoke L, Taghon T, et al. A randomized trial comparing sevofluraneand propofol in children undergoing MRI scans. Paediatr Anaesth 2009;19:672–681.

Study that compared three primary outcomes (pausing the MRI scan, emergencequality and respiratory complications for propofol and sevoflurane). The propofolgroup had more pausing and less agitation than the sevoflurane group.

37 Lutterbey G, Wattjes G, Doerr D, et al. Atelectasis in children undergoingeither propofol infusion or positive pressure ventilation anesthesia for mag-netic resonance imaging. Paediatr Anaesth 2007; 17:121–125.

38 Blitman N, Lee H, Jain VR, et al. Pulmonary atelectasis in children anesthetizedfor cardiothoracic MR: evaluation of risk factors. J Comput Assist Tomogr2007; 31:789–794.

orized reproduction of this article is prohibited.