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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Retrospectively registered

Titles & IDs
Public title
Comparing the efficacy and safety between Propofol And Dexmedetomidine for sedation in claustrophobic Adults undergoing Magnetic resonance imaging (PADAM)
Scientific title
A randomized controlled trial comparing target controlled infusion (TCI) propofol versus dexmedetomidine infusion for the treatment of anxiety in claustrophobic adults undergoing magnetic resonance imaging (MRI)
Secondary ID [1] 287784 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Claustrophobia in adults 296669 0
Condition category
Condition code
Anaesthesiology 296895 296895 0 0
Mental Health 297055 297055 0 0

Study type
Description of intervention(s) / exposure
Recruitment steps:
1. Patients were recruited from the MRI room or registry.
2. Recruited patients were slotted into a designated time for research studies under the bio-imaging department or following their original date and time of appointment depending on which one would be earlier or convenient to the patients.
4. Patients were explained the risks and purpose of study and written informed consent was taken prior to procedure.
5. Following the trial number, patients were randomized to either:

Group A: The attending anaesthetist would administer Propofol (10mg/ml) infusion, using Target Controlled Infusion (TCI) with Schnider’s pharmacokinetic model for target effect site. Drug boluses and infusions are administered according to ideal bodyweight. TCI infusion was started at a rate of 1.5 mcg/kg until the steady state was achieved then titrated with increment of 0.1mcg/kg to achieve Ramsay Sedation Score (RSS) of 3.

Group B: The attending anaesthetist would administer Dexmedetomidine (4mcg/ml) infusion and administered according to ideal bodyweight. Loading dose of 1mcg/kg/min was given within 10 minutes and infusion was started at the rate of 0.2mcg/kg/hr and titrated by increment of 0.1mcg/kg/hr and above to achieve RSS of 3. Dosing was instituted according to the dexmedetomidine (Precedex) guidelines.

It was a double-blinded study whereby both patients and the attending radiographer (the same person who would perform the Spielberg Anxiety and Visual Anxiety Scores).

On the day of the re-scheduled MRI scan:
1. Patient was fasted for at least 6 hours before the scheduled scan.
2. No premed was given.
3. An Intravenous cannula (20-22G) was inserted to start 500mls of crystalloid as fluid maintenance.
4. Patient entered the scanning room for 5 minutes before being asked to answer the Spielberger Straits Traits Anxiety Score and Visual Anxiety Score to determine their anxiety levels pre-examination by the attending radiolographer.
5. Standard monitoring with non-invasive blood pressure (NIBP), heart rate, Pulse Oxymetry and electrocardiogram (ECG) was applied, monitored and recorded throughout the scan.
6. Oxygen 3L/min via nasal prong was given to the subjects.
7. A fully equipped emergency trolley and airway management was on standby in the MRI room vicinity at all times.
8. The sedative agent according to the randomized group was given intravenously and titrated until patient achieved RSS of 3.
9. Time when the drug infusion started and the time taken to achieve RSS score of 3 were recorded.
10. Once RSS of 3 was achieved, patient entered the MRI tunnel.
11. Any failed scans were recorded and reasons documented.
12. Adverse events during the scan such as
i) Drop in blood pressure > 20% from baseline or requires vasopressors
ii) Bradycardia <50 beats per min
iii) Desaturation < 95% requiring airway and ventilation support
iv) Over sedation
were recorded and managed appropriately by the attending anaesthetist.

After the scan:
1. Patient was monitored in the recovery bay.
2. After 5 minutes in recovery, patient was asked again to answer the Spielberger Straits Traits Anxiety Score and Visual Anxiety Score to determine their anxiety levels post examination by the same attending radiographer.
3. Vital signs and sedation scores were recorded for every half an hour until ready for discharge.
4. Any side effects or complications including hypotension, bradycardia or respiratory instability were managed accordingly.
5. The patient will be allowed home by the anaesthetist once all discharge criteria were fulfilled:
v) Fully conscious
vi) Hemodynamically stable
vii) Able to perform physical activity without support or with minimal support.
viii) No nausea or vomiting

6. Before going home, patient was asked to fill in a Patient Satisfaction Score form.
7. All data collected was analyzed statistically using SPSS.
Intervention code [1] 293175 0
Treatment: Drugs
Comparator / control treatment

Control group

Primary outcome [1] 296502 0
Anxiety assessed using the Visual Anxiety Score and Speilberger Straits Test Anxiety Inventory score taken in the MRI scanner and after completing the MRI scan
Timepoint [1] 296502 0
Before the start of the sedation and after completion of procedure.
Primary outcome [2] 296503 0
The number of patients who were unable to complete the MRI
Timepoint [2] 296503 0
anytime from start until completion of MRI
Secondary outcome [1] 318627 0
i) To compare patient’s satisfaction using Visual Satisfaction Score chart.
Timepoint [1] 318627 0
Time just before discharge
Secondary outcome [2] 318628 0
To document number of adverse events in both groups during the scans such as
i) Drop in blood pressure > 20% from baseline or requires vasopressors
ii) Bradycardia <50 beats per min
iii) Desaturation < 95% requiring airway and ventilation support
iv) Over sedation
Timepoint [2] 318628 0
start of sedation until discharge

Key inclusion criteria
1. ASA I - II according to American Society of Anaesthesiologist guidelines.
2. Patients age 18 - 70 years old.
3. Known case of claustrophobia or history of anxiety/panic attack during an MRI study
4. Patients who were scheduled to undergo an MRI scan for a medical or surgical problem
Minimum age
18 Years
Maximum age
70 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
1. Patient related - Patient refusal
BMI >30
Hypotension due to any reasons. (Systolic less than 90 mmHg)
Bradycardia (heart rate less than 50 bpm)
Concurrent medication which increase vagal tone or delay AV conduction (e.g.. digoxin / beta blocker)
Chronic lung disease with saturation on room air <91%
Obstructive sleep apnoea
Requires general anaesthesia
2. Drug related - Allergic history to propofol or dexmedetomidine or related compound
3. MRI related - Any contraindications to MRI
Emergency MRI
Interventional procedures

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
A research assistant will organize the randomization for 30 subjects using an online randomization table, label the group numbers 1 or 2 and seal the numbers in opaque envelopes.
An anaesthetist will screen for suitable subjects and once consent was obtained, the sealed envelopes will be opened prior to starting the MRI procedure.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s

The people assessing the outcomes
The people analysing the results/data
Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
Sample Size:
A total of 30 patients as subjects with n=15 in each arm were recruited. Calculation of sample size was done using G Power Software by UCLA University. The effect size difference was estimated at 0.6 using a dependent t-test based on objective 1. To achieve a=0.05 and power (1-ß) >80%, total sample size calculated was 24. An estimation of 20% drop out rate made the total sample size to be a final 30.

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment outside Australia
Country [1] 7291 0
State/province [1] 7291 0
Kuala Lumpur

Funding & Sponsors
Funding source category [1] 292317 0
Name [1] 292317 0
Postgraduate Research Fund University of Malaya
Address [1] 292317 0
Institute of Postgraduate Studies
University of Malaya
50603 Kuala Lumpur
Country [1] 292317 0
Primary sponsor type
Pui-San Loh
Department of Anaesthesiology,
Faculty of Medicine
University Malaya
Lembah Pantai
50603 Kuala Lumpur
Secondary sponsor category [1] 290995 0
Name [1] 290995 0
Address [1] 290995 0
Country [1] 290995 0

Ethics approval
Ethics application status
Ethics committee name [1] 293789 0
Ethics committee address [1] 293789 0
Ethics committee country [1] 293789 0
Date submitted for ethics approval [1] 293789 0
Approval date [1] 293789 0
Ethics approval number [1] 293789 0
MECID NO:20148-432 , NMRR 14-1260-22799

Brief summary
Magnetic Resonant Imaging (MRI) is now widely used in clinical investigations. However, because of the design of MRI, patients are required to lie still in an enclosed tunnel like machine for some time. This poses a great challenge to patients who are claustrophobic. Most of these individuals will require sedation to reduce their anxiety in order to tolerate and complete the scan. Traditionally, benzodiazepines are the most frequently used dugs for sedation but now, more drugs with reliable and predictable pharmacological profiles are available such as propofol and dexmedetomidine.
The aim of this study is to compare the efficacy and safety of propofol and dexmedetomidine as sedation to reduce the anxiety levels of claustrophobic adults undergoing MRI. This is a prospective randomized double-blinded study involving 30 adult claustrophobic patients planned for elective MRI for a medical or surgical reason in University Malaya Medical Center, Malaysia. Each group will be equal in numbers with group A receiving Propofol via Target Controlled Infusion using Schneider Model and Group B receiving Dexmedetomidine given by the attending anaesthetist. Anxiety levels will be assessed with Visual Anxiety Score (VAS) and Spielberger Straits Test Anxiety (STAI) Score taken before the drug was given and after completing the MRI scan. Adverse effects occurring during the sedation will be documented together with patient satisfaction scores before they go home.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 61306 0
Dr Pui-San Loh
Address 61306 0
Department of Anaesthesiology,
Faculty of Medicine,
University of Malaya,
Lembah Pantai,
50603 Kuala Lumpur,
Country 61306 0
Phone 61306 0
Fax 61306 0
Email 61306 0
Contact person for public queries
Name 61307 0
Dr Mohamad Azlan bin Ariffin
Address 61307 0
Department of Anaesthesiology,
Faculty of Medicine,
University of Malaya,
Lembah Pantai,
50603 Kuala Lumpur,
Country 61307 0
Phone 61307 0
Fax 61307 0
Email 61307 0
Contact person for scientific queries
Name 61308 0
Dr Pui-San Loh
Address 61308 0
Department of Anaesthesiology,
Faculty of Medicine,
University of Malaya,
Lembah Pantai,
50603 Kuala Lumpur,
Country 61308 0
Phone 61308 0
Fax 61308 0
Email 61308 0

No information has been provided regarding IPD availability
Summary results
Have study results been published in a peer-reviewed journal?
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary