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Trial registered on ANZCTR
Registration number
ACTRN12612000996864
Ethics application status
Approved
Date submitted
11/09/2012
Date registered
17/09/2012
Date last updated
16/10/2015
Type of registration
Prospectively registered
Titles & IDs
Public title
A randomised study to see if two drugs that increase blood pressure, namely phenylephrine and metaraminol, are equally effective to preventing blood pressure falls and in resulting in a healthy baby, at the time of spinal anaesthesia for elective caesarean section
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Scientific title
A randomised clinical trial at the time of spinal anaesthesia for elective caesarean section to investigate the effect of equipotent phenylephrine and metaraminol infusions on neonatal outcome
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Secondary ID [1]
281135
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Nil
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Universal Trial Number (UTN)
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Trial acronym
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Linked study record
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Health condition
Health condition(s) or problem(s) studied:
Neonatal acid-base status.
287305
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Anaesthesia for elective caesarean section
287428
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Condition category
Condition code
Anaesthesiology
287640
287640
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0
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Anaesthetics
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Reproductive Health and Childbirth
287762
287762
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0
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Complications of newborn
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Intervention/exposure
Study type
Interventional
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Description of intervention(s) / exposure
Metaraminol intravenous infusion at 25 mcg/min commenced at the time of spinal anaesthesia for elective caesarean section and completed at the time of delivery
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Intervention code [1]
285599
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Treatment: Drugs
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Intervention code [2]
285676
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Prevention
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Comparator / control treatment
Active comparitor is a phenylephrine intravenous infusion at 50 mcg/min commenced at the time of spinal anaesthesia for elective caesarean section and completed at the time of delivery
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Control group
Active
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Outcomes
Primary outcome [1]
287895
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Neonatal acid-base status at birth, as determined by uterine artery pH.
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Assessment method [1]
287895
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Timepoint [1]
287895
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Cord blood taken at time of birth.
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Secondary outcome [1]
299001
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Uterine venous pH, pCO2, pO2, standard base excess; p(A-V)CO2 difference, and incidence of umbilical venous pH < 7.20
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Assessment method [1]
299001
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Timepoint [1]
299001
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Cord blood taken at time of birth.
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Secondary outcome [2]
299002
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Incidence of maternal hypotension (defined as a reduction in systolic blood pressure by at least 10% below baseline, using an automated sphygmomanometer).
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Assessment method [2]
299002
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Timepoint [2]
299002
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From injection of spinal anaesthetic drugs until delivery of the neonate
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Secondary outcome [3]
299003
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Incidence of maternal bradycardia (defined as a fall in heart rate below 60 beats per minute, using a pulse oximeter)
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Assessment method [3]
299003
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Timepoint [3]
299003
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From injection of spinal anaesthetic drugs until delivery of the neonate
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Secondary outcome [4]
299004
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Incidence of maternal hypertension (defined as an increase in systolic blood pressure of at least 10% above baseline, using an automated sphygmomanometer).
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Assessment method [4]
299004
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Timepoint [4]
299004
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From injection of spinal anaesthetic drugs until delivery of the neonate
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Secondary outcome [5]
299005
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Neonatal Apgar scores at 1 and 5 minutes.
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Assessment method [5]
299005
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Timepoint [5]
299005
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1 and 5 minutes after birth of the neonate
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Eligibility
Key inclusion criteria
1. Women undergoing elective Caesarean section
under spinal or combined spinal epidural (CSE)
anaesthesia
2. Gestational age > 37 weeks
3. Singleton pregnancy
4. ASA I and II
5. Height between 150 and 190 cm
6. Weight between 50 and 115 kg
7. Body mass index (BMI) between 20 and 35 kg/m2
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Minimum age
18
Years
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Maximum age
No limit
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Sex
Females
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Can healthy volunteers participate?
No
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Key exclusion criteria
1. Contraindication to spinal or CSE anaesthesia
2. Diabetes mellitus
3. Preeclampsia, pregnancy-induced hypertension or
essential hypertension
4. Cardiovascular or cerebrovascular disease
5. Fetal abnormality or intrauterine growth restriction
6. Failure to establish block to cold to T4
7. Supplementary epidural anaesthesia prior to
delivery of the baby
8. Conversion to general anaesthesia
9. Excessive shivering that makes blood pressure
monitoring unreliable
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Study design
Purpose of the study
Prevention
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Allocation to intervention
Randomised controlled trial
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Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Recruitment will take place at pre-admission clinics, in the Labour and Birthing Suite, the Maternal-Fetal Assessment Unit or a hospital ward, as appropriate. Group assignment based on computer generated randomisation sequence will be by sealed opaque envelope, numbered sequentially.
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Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Consenting women will be randomised by computer-generated random number sequence to either phenylephrine (Group P) or metaraminol (Group M).
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Masking / blinding
Blinded (masking used)
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Who is / are masked / blinded?
The people receiving the treatment/s
The people administering the treatment/s
The people assessing the outcomes
The people analysing the results/data
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Intervention assignment
Parallel
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Other design features
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Phase
Phase 4
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Type of endpoint/s
Safety/efficacy
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Statistical methods / analysis
Non-inferiority trial
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Recruitment
Recruitment status
Completed
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Date of first participant enrolment
Anticipated
1/11/2012
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Actual
4/02/2013
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Date of last participant enrolment
Anticipated
30/04/2015
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Actual
26/06/2015
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Date of last data collection
Anticipated
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Actual
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Sample size
Target
180
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Accrual to date
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Final
186
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Recruitment in Australia
Recruitment state(s)
WA
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Recruitment postcode(s) [1]
9367
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6168 - Rockingham
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Funding & Sponsors
Funding source category [1]
285924
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Other
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Name [1]
285924
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ANZCA
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Address [1]
285924
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Australian and New Zealand College of Anaesthetists
ANZCA House, 630 St Kilda Road, Melbourne Vic 3004
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Country [1]
285924
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Australia
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Primary sponsor type
Hospital
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Name
King Edward Memorial Hospital for Women
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Address
374 Bagot Rd, Subiaco, WA 6008
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Country
Australia
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Secondary sponsor category [1]
284744
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None
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Name [1]
284744
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Address [1]
284744
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Country [1]
284744
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Ethics approval
Ethics application status
Approved
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Ethics committee name [1]
287950
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Women and Newborn Health Services Ethics Committee
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Ethics committee address [1]
287950
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Room 134 Level 1 Children's Clinical Research Facility Princess Margaret Hospital GPO Box D184 Perth WA 6840
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Ethics committee country [1]
287950
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Australia
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Date submitted for ethics approval [1]
287950
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28/08/2012
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Approval date [1]
287950
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30/01/2013
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Ethics approval number [1]
287950
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Summary
Brief summary
Caesarean section is one of the most commonly performed procedures in Australia and many other countries. Approximately 80-90% of all caesarean sections performed in developed countries are conducted under regional anaesthesia. Due to the high incidence of maternal hypotension after spinal anaesthesia for elective caesarean delivery (approximately 70-80% in the absence of prophylaxis with sympathomimetic drugs), it has become routine practice in many centres worldwide to administer a sympathomimetic drug to support the blood pressure, either prophylactically, which is more effective, or as treatment. Phenylephrine has been extensively investigated and has become the first-line sympathomimetic drug for prophylactic continuous infusion. Spinal anaesthesia induces systemic vasodilation and a mild fall in arterial pressure, accompanied initially by a compensatory rise in heart rate and cardiac output. Preventing reduced maternal cardiac output and a substantial fall in maternal arterial pressure (and possibly prevention of even minor reductions in blood pressure of less than 10% from baseline values) is considered fundamental to avoiding maternal nausea, vomiting, syncope and neonatal hypoxaemia and acidosis. Phenylephrine, which has almost no beta-agonist activity, and in higher doses causes a baroreceptor mediated reflex bradycardia, reduction in stroke volume because of increased afterload, shift of blood into the splanchnic venous circulation decreasing venous return and thus a dose-dependent fall in cardiac output. These factors may, if severe, be detrimental to placental perfusion. An alternative sympathomimetic drug and alpha-adrenergic agonist is metaraminol. This drug differs from phenylephrine in having mixed direct and indirect alpha- and beta-agonist effects (although direct alpha- effects predominate at clinical doses). It is more effective than ephedrine in maintaining arterial pressure and its pharmacological properties suggest it might have advantages over phenylephrine, by maintaining cardiac output more effectively. Limited evaluation shows it is associated with excellent neonatal outcomes and metaraminol is widely used in non-obstetric clinical practice. There are no human data comparing phenylephrine and metaraminol in pregnancy. We have established that the potency ratio between these drugs is approximately 1:4-5, so infusions will be commenced at equipotency, based on a well supported dose of phenylephrine. The rate of metaraminol will be consistent with the only previous human trials, in which it was used at 250 mcg/min initially and maximum rates approached 500 mcg/min. This non-inferiority study will compare these two well-known sympathomimetic drugs with respect to neonatal and maternal outcome. Should metaraminol be found to compare favourably with phenyephrine, it would provide good evidence that it is a suitable option in this setting.
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Trial website
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Trial related presentations / publications
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Public notes
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Contacts
Principal investigator
Name
34650
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Dr Nolan McDonnell
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Address
34650
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Department of Anaesthesia and Pain Medicine King Edward Memorial Hospital Bagot Road Subiaco WA 6008
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Country
34650
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Australia
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Phone
34650
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+61893402222
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Fax
34650
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+61893402227
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Email
34650
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[email protected]
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Contact person for public queries
Name
17897
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Michael Paech
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Address
17897
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Department of Anaesthesia and Pain Medicine
King Edward Memorial Hospital
Bagot Road
Subiaco WA 6008
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Country
17897
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Australia
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Phone
17897
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+61893402222
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Fax
17897
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+61893402227
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Email
17897
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[email protected]
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Contact person for scientific queries
Name
8825
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Michael Paech
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Address
8825
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Department of Anaesthesia and Pain Medicine
King Edward Memorial Hospital
Bagot Road
Subiaco WA 6008
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Country
8825
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Australia
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Phone
8825
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+61893402222
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Fax
8825
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+61893402227
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Email
8825
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[email protected]
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No information has been provided regarding IPD availability
What supporting documents are/will be available?
No Supporting Document Provided
Results publications and other study-related documents
Documents added manually
No documents have been uploaded by study researchers.
Documents added automatically
No additional documents have been identified.
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