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Volume 32, 12 Issues, 2022
  Original Article     November 2022  

Comparative Sedation with Sevoflurane and Thiopental in Children Undergoing MR Imaging

By Nurettin Kurt1, Duygu Karakose Caliskan2, Haci Yusuf Gunes1


  1. Department of Anaesthesiology and Reanimation, Faculty of Medicine, Van Yuzuncu Yil University, Van, Turkey
  2. Department of Anaesthesiology and Reanimation, SBU Van Training and Research Hospital, Van, Turkey
doi: 10.29271/jcpsp.2022.11.1381

Objective: To compare the use of propofol and thiopental in children undergoing MRI.
Study Design: Descriptive, comparative study.
Place and Duration of Study: University of Health Sciences, Van Training and Research Hospital, Van, Turkey, between January 01 and December 31, 2019.
Methodology: One thousand two hundred and twenty two paediatric patients having MRI were included and divided into two groups. Patients aged 2-18 years who were administered Propofol were classified as Group I, and the patients under the age of 2 years who were administered Thiopental were classified as group II. All patients received Sevoflurane insufflation via face mask after induction agent. Patient’s demographic data, ASA scores, anaesthesia-procedure-recovery times, comorbidities, type of MRI examination and complications were recorded.
Results: Age, body weight and ASA score of the patients in Group I were higher than Group II (p<0.05). Epilepsy, cerebral palsy, mental retardation, speech retardation and autism were more prevalent in Group I than in Group II (p<0.05). Neuromuscular growth retardation, hydrocephalus, and metabolic disease were less common in Group I than in Group II (p<0.05). With this Apnea and desaturation was higher in Group I, and bradycardia was higher in Group II.
Conclusion: Sevoflurane insufflation with a face mask can be safely used in children after induction of anaesthesia with propofol or thiopental.

Key Words: Sedation, Paediatric  patients, Propofol, Thiopental, Sevoflurane.


Today, various invasive and non-invasive interventions have been put into practice in non-operating room environments for the purpose of diagnosis and treatment of patients. With these Non-Operating Room Anaesthesia (NORA) applications, the need for sedation or sedoanalgesia and general anaesthesia have emerged. NORA applications are most commonly seen in diagnostic and interventional radiology, dentistry, gastroenterology, cardiology, urology for paediatric cases, and magnetic resonance imaging (MRI) is the most frequently used diagnostic/follow-up imaging method in NORA applications for paediatric patients.1,2

Sedation  applications  that  are  performed  outside  the  operating  room  are  riskier  when  compared  to  operating  room  conditions.  For example, anaesthesiologists have difficulty in reaching a patient's airway during an MRI procedure. MRIs  are  one  of  the  most  critical  procedures  that  require  anaesthesia  for  children. During  the  MRI  procedure,  the  most  common  problems  are  related  to  monitoring.  In  addition,  mental  retardation,  cerebral  palsy,  epilepsy,  and  limitations  of  the  anaesthesia  environment  accompanying  the  cases  are  added  to  these  problems.3 Therefore,  the  prepared  guidelines  recommend  providing  appropriate  monitoring  and  adequate  equipment,  prioritising  patient safety.4

Ideal sedation in NORA applications for patients in the paediatric  age group state that it should reduce anxiety, awareness and fear, provide immobility and early recovery from the procedure, increase amnesia and ensure patient safety.5,6 The effects of anaesthetic drugs used for this purpose, which affect the respiratory, cardiovascular, haematological and neurological systems, should be minimal, and the patient should be recovered as soon as possible.7 For NORA applications, there are different sedation applications used for children. Since the satisfaction, side effects and complication rates of these applications are different, there is no consensus on which application is better.8

The aim of this study was to compare, according to the drug combinations used, the side effect profiles, complications and discharge status of paediatric patients who were sedated during MRI.


After obtaining ethics committee approval, number 2021/01 and dated 07.01.2021, at the University of Health Sciences Van Training and Research Hospital, the anaesthesia forms of 1,222 paediatric  patients, who had undergone an MRI procedure under anaesthesia between January 01, 2019, and December 31, 2019, were analysed using the hospital’s automated database and anaesthesia follow-up form. All paediatric patients under the age of 18 years who underwent an MRI under anaesthesia with full and complete data available included study. Cases whose data could not be accessed from either the anaesthesia follow-up form or from the hospital’s automated database were excluded from the study.

The anaesthetic agents used, age, gender, ASA (American Society of Anaesthesiologists) score, comorbidities, organs examined, demographic data, discharge status, duration of the procedure, duration of anaesthesia, and complications (apnea, hypoxia, bradycardia, cardiac arrest) were recorded.

A 25% decrease in heart rate from normal was considered as bradycardia and was intervened with 0.02 mg/kg atropine. It was accepted as hypoxia when peripheral oxygen saturation decreased below 90% at any time during the study. In case of hypoxia, intervention was to change the patient's head position, increasing the oxygen flow or switching to mask ventilation. It was determined that the patients who were scheduled for MRI were evaluated in the outpatient clinic before the procedure and written consent was obtained from their parents. It was seen in the patient consent files that the fasting periods were indicated as 2 hours for clear liquids, 4 hours for breast milk, 6 hours for formula, and 8 hours for solid foods before the MRI scan.

On the morning of the procedure, vascular access was established with a 22G or 24G cannula, and the patients were routinely monitored, followed by blood pressure, heart rate, and SpO2. To prevent carbon dioxide retention, 4 L/minute oxygen was given with a face mask. All patients were routinely administered 0.05 mg/minute midazolam as premedication. The files of the patients were examined, and the patients were divided into two groups according to the drug combinations used for the MRI procedure. The patients aged 2-18 years who were administered propofol were classified as Group I (n=884), and the patients under the age of 2 years who were administered thiopental were classified as Group II (n=338).

All patients were taken to the room where the MRI was going to be taken and monitored, and then administered 0.05 mg/kg midazolam. After the anaesthetic agent (propofol or thiopental) was administered, 2 MAC (Minimum Alveolar Concentration) sevoflurane insufflation via a face mask and 4L/min oxygen was opened for all patients. Sevoflurane insufflation via a face mask was turned off 2 minutes before the end of the imaging procedure. At the end of the procedure, the patients were transferred to the post anaesthesia care unit (PACU). Recovery time was defined as the time between the end of the procedure and the patient’s admission to the PACU.

Statistical analyses were done with SPSS 15.5 for Windows package program. In the descriptive statistics of the data, mean, standard deviation, median minimum, maximum, frequency, and percentage values ​​were used. The distribution of variables was measured with the Kolmogorov-Smirnov test. The Mann-Whitney U-test was used in the analysis of quantitative non-normally distributed data. The chi-square test was used in the analysis of qualitative independent data. Type-I error level was accepted as 0.05 in all analyses.


For the 1,222 paediatric  patients who underwent NORA for an MRI procedure between January and December 2019 at the Health Sciences University in the Van Training and Research Hospital, the gender distribution was 705 (57.7%) males, 517 (42.3%) females, the median age was 3.0 years and the interquartile ratio (IQR) was 1.0 – 5.0, the median weight was 13.0 kilograms and the IQR was 9.0 – 18.0, the median anaesthesia time was 12.0 minutes and the IQR was 11.0 – 14.0, the median procedure time was 11.0 minutes and the IQR was 10.0 – 13.0. Of the 1,222 paediatric patients, 545 (44.6%) were ASA I and 677 (55.4%) were ASA II.

While age, body weight, and ASA score of the patients in Group I were statistically higher than Group II (p<0.05), their gender distribution and comorbidity rates did not differ (p<0.05, Table I).

The most common region scanned with MRI was the brain, followed by spine imaging (Table II).

Intubation was not applied to any of the sedated patients. Apnea and desaturation rates were higher in Group I, and bradycardia rates were higher in Group II (p<0.05). However, discharge rates did not differ between groups (p<0.05, Table II).


Choosing the sedation agent to be used for radiological imaging in the paediatric age group is quite challenging for clinicians. The selected agent should induce immobilisation but not cause respiratory depression. The ideal sedative agent should be effective, provide rapid onset and recovery, and have no side effects. For this purpose, many agents such as chloralhydrate, midazolam, ketamine, propofol, thiopental, dexmedetomidine, and sevoflurane are used singly or in combinations. Even in the use of short-acting sedatives, one should be prepared for the unexpected, prolonged effects of the drug.9,10

Table I: Demographic and procedural data of patients by group.


Group I

(Median / IQR / n%)

Group II

(Median / IQR / n%)


Age (years)

4.0 / 3.0-6.0

1.0 / 0.0-1.0


Weight (Kg)

16.0 / 12.0-21.0

7.0 / 6.0- 9.0




522 / 59.0%

183 / 54.1%



362 / 41.0%

155 / 45.9%




366 / 41.4%

179 / 53.0%



518 / 58.6%

 159 / 47.0%

Anaesthesia duration (min)

12.0  / 11.0-0.13.0

13.0 / 12.0-15.0


Procedure duration (min)

11.0  / 10.0-12.0

12.0 / 11.0-13.0


Recovery time (min)

1.0 / 1.0-2.0

1.0 / 1.0-2.0




819 / 92.6%

319 / 94.4%



65 / 7.4%

19 / 5.6%


47 / 5.3%

12 / 3.5%



18 / 2.0%

7 / 2.1%


m Mann-Whitney u test / Ki-kare test.

Table II: Scanned region complications and discharge status for each group.



Group I (n/%)

Group II (n/%)


Brain MRI


787 / 89.0%


306 / 90.5%



Brain + total spine MRI


42 / 4.8%  


13 / 3.8%


Lumbar spine MRI


17 / 1.9%  


7 / 2.1%   


Joint MRI


23 / 2.6%


6 / 1.8%  




15 / 1.7%


6 / 1.8%   



Not required

884 / 100.0%


33 / 100.0%




0 / 0.0%


0 / 0.0%



848 / 95.9%


322 / 95.3%




36 / 4.1%


16 / 4.7%


24 / 2.7%


5 / 1.5%




10  1.1%


3 / 0.9%




2 / 0.2%


8 / 2.4%



Discharge status


878 / 99.3%


335 / 99.1%




5 / 0.6%


2 / 0.6%



Intensive care

1 / 0.1%


1 / 0.3%



Ki-kare test         

In this study, thiopental was used in patients under 2 years of age and propofol was used in patients 2 to 18 years. In addition to the IV anaesthetic agent used, sevoflurane insufflation via face mask of 2 MAC (with 4 L/min Oxygen) was used for maintenance in all patients. No additional doses of an IV anaesthetic agent were used in any of the patients.

In this study comparing propofol and thiopental, no difference was found between the duration of anaesthesia in the propofol Group I and thiopental Group II patients. The incidence of apnea and desaturation in the propofol-administered patients were higher, while bradycardia rates were higher in the thiopental-administered group. There was no need for intubation and cardiac arrest did not develop in any of the cases, and discharge rates were similar. Especially since a homogeneous age was not planned for the groups in this study, it can be said that the complications developed are not only affected by the anaesthetic agent used but also by the age of the patient.

In a study, the authors stated that propofol alone could not provide the immobilisation required for an MRI procedure and that it required repeated doses, while repeated doses caused respiratory depression and the loss of protective airway reflexes.11 Unlike this study, sevoflurane insufflation was used, instead of repeated doses of propofol, for maintenance after a single dose of propofol or thiopental was used. In this way, it was observed that less respiratory depression and less loss of airway reflexes were encountered.

To avoid the possible side effects of propofol, paediatric anaesthesiologists combine it with various agents such as midazolam and dexmedetomidine, although this prolongs the recovery period of the patient.12,13 In this study, 0.05 mg/min midazolam was administered to all patients for premedication.

In a case-control study conducted by Tith et al., with patients who underwent a non-cardiac MRI, 10% of sedated patients experienced complications, of which 96% of the complications experienced were reported as minor complications such as airway obstruction and transient oxygen desaturation requiring intervention. It has been emphasised that the combined use of propofol and thiopental reduces the risk of complications compared to the use of only propofol or repeated doses of the drug.14 The authors believe that the lower complication rate (4.3%) in this study is due to the absence of repeated dose use and the use of sevoflurane insufflation via face mask for maintenance instead. It is also supported by other studies that propofol in paediatric diagnostic imaging procedures causes more respiratory side effects and physiological changes compared to other drugs.15,16 However, these respiratory effects can often be successfully managed with simple airway interventions.17

In the study of Kim et al., in which they examined the risk factors for unplanned intubation during sedation-guided MRI, a high ASA score, prematurity, presence of gastroesophageal reflux and congenital heart disease were found to be risk factors for unplanned intubation during MRI.18 Although comorbidities such as epilepsy, cerebral palsy, and motor mental retardation were found in this study, no complications that would cause unplanned intubation were observed.

In a study conducted by Mallory et al., they compared the use of propofol and thiopental in paediatric patients undergoing an MRI under sedation and found vomiting and allergic reactions were more common in patients that were administered thiopental, and the need for antiemetic drugs increased. They emphasised that this situation prolongs the recovery period and reduces parental satisfaction.16

In a study in which the combination of propofol and remifentanil was compared with the use of sevoflurane, it was reported that the use of propofol plus remifentanil provided faster recovery and caused less delirium but stated that an additional dose was needed due to movement in children during the imaging.19 In this study, using an IV anaesthetic only in induction, not using it in repetitive doses, and using sevoflurane insufflation in maintenance, it was observed that this caused fewer complications in patients and does not require additional anaesthetic by causing less movement in children during imaging.

This study has several limitations. First, this study was designed retrospectively. The data was obtained from the anaesthesia follow-up form and the hospital’s automated database, which may lead to suspicions of bias. Moreover, additional monitoring, such as bispectral index monitoring, to help evaluate the depth of sedation, could not be performed on the patients.


Since MRI is a long scan, it has been observed that a single dose IV anaesthetic agent is insufficient, and that additional anaesthetic drugs are needed for maintenance, as well as sevoflurane insufflation, which is used as an additional anaesthetic drug for this purpose and provides sufficient immobility in patients. Sevoflurane insufflation can be used safely after induction of anaesthesia with propofol or thiopental and it reduces recovery times.

The study was approved by Health Sciences University in the Van Training and Research Hospital, Clinical Research Ethics Committee (Approval No. 07.01.2021/01).

The study was conducted in accordance with the principles of the Declaration of Helsinki.

The authors declared no competing interest.

NK: The acquisition, analysis and interpretation of data for the work, drafting and revising the manuscript critically for important intellectual content.
DKC, HYG: The acquisition and analysis of data for the work.
All authors approved the final version of the manuscript to be published.


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