ANZCTR - Registration

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Trial registered on ANZCTR

Registration number

ACTRN12617000830392

Ethics application status

Approved

Date submitted

31/05/2017

Date registered

6/06/2017

Date last updated

7/05/2018

Type of registration

Prospectively registered

Titles & IDs

Public title

Effect of intraoperative magnesium on the incidence of chronic post surgical pain after thoracotomy

Scientific title

Effect of intraoperative magnesium on the incidence of chronic post surgical pain after thoracotomy

Secondary ID [1]

None

Universal Trial Number (UTN)

U1111-1197-1970

Trial acronym

Linked study record

Health condition

Health condition(s) or problem(s) studied:

Chronic post-thoracotomy pain

Condition category

Condition code

Surgery

Other surgery

Anaesthesiology

Pain management

Intervention/exposure

Study type

Interventional

Description of intervention(s) / exposure

The aim of this study is to investigate the effects of intraoperative systemic magnesium on chronic postsurgical pain in patients undergoing thoracotomy. A bolus dose of 50mg/kg of magnesium (magnesium sulfate) will be administered for 15 minutes immediately after induction and prior to skin incision, followed by infusion at 10mg/kg/hr which will be continued until the patient has been transferred to the Post Anaesthesia Care Unit (PACU).

Intervention code [1]

Treatment: Drugs

Comparator / control treatment

Patients in the control group will be administered and infused the same volume of isotonic saline.

Control group

Placebo

Outcomes

Primary outcome [1]

Assess the incidence of chronic post surgical pain at 2 and 6 months post thoracotomy.

This will be done via a telephone call from a pain nurse at 2 and 6 months post thoracotomy. A simple yes/no categorical outcome will be used and patients reporting pain will be asked to present to a chronic pain clinic for further assessment by an anaesthetist. At this visit, a 0-10 point numeric rating scale (NRS) will be used to measure the degree of pain intensity.

Timepoint [1]

2 and 6 months post operation

2 months post operation is the primary endpoint

Secondary outcome [1]

Evaluate the duration of hospital stay

Timepoint [1]

At hospital discharge

Secondary outcome [2]

Evaluate intraoperative opioid requirements (in morphine equivalents) by reviewing the anaesthetic record.

Timepoint [2]

At surgery completion

Secondary outcome [3]

Evaluate opioid/local anaesthetic requirements (converted to morphine and ropivacaine equivalents).

This will be done by evaluating analgesic requirements which will have been documented on standard hospital pain protocol forms.

Timepoint [3]

Opioid/local anaesthetic requirements will be assessed at 24 and 48 hours post surgery

Secondary outcome [4]

Characterise the intensity and type of CPSP. This is a composite secondary outcome. A 0-10 point numeric rating scale (NRS) will be used to measure the degree of pain intensity. Type of CPSP will be assessed using the Neuropathic Pain Questionnaire (NPQ).

Timepoint [4]

2 and 6 months post thoracotomy

Secondary outcome [5]

Evaluate postoperative pain scores. Pain scores will be measured using a 0-10 point numeric rating scale (NRS).

Timepoint [5]

This will be done at 24 and 48 hours post surgery.

Secondary outcome [6]

Health related quality of life

This will be assessed using the Medical Outcome Study 36-Item Short Form (SF-36). This form will be sent to all participants. The SF-36 is a widely used instrument that is standardized and validated. It assesses eight scales: physical functioning, role functioning-physical, bodily pain, general health, energy, social functioning, role functioning-emotional, and mental health.

Timepoint [6]

6 months post thoracotomy

Eligibility

Key inclusion criteria

18 to 80 years of age, male or female gender, scheduled for elective thoracotomy surgery, ASA physical status class I to III, body mass index <40kg/cm2

Minimum age

18 Years

Maximum age

80 Years

Sex

Both males and females

Can healthy volunteers participate?

Key exclusion criteria

Allergy to magnesium sulfate, major hepatic or renal failure, presence of neurologic disease, second or third degree atrioventricular block, pre-existing treatment with magnesium or calcium channel blockers. Patients with chronic neuropathic pain due to any cause will also be excluded from this clinical trial.

Study design

Purpose of the study

Treatment

Allocation to intervention

Randomised controlled trial

Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)

Block randomisation and sealed envelope method

Methods used to generate the sequence in which subjects will be randomised (sequence generation)

Permuted block randomisation

Masking / blinding

Blinded (masking used)

Who is / are masked / blinded?

The people receiving the treatment/s
The people administering the treatment/s

Intervention assignment

Parallel

Other design features

Phase

Type of endpoint/s

Statistical methods / analysis

Recruitment

Recruitment status

Recruiting

Date of first participant enrolment

Anticipated

1/08/2017

Actual

7/05/2018

Date of last participant enrolment

Anticipated

1/08/2018

Actual

Date of last data collection

Anticipated

14/11/2019

Actual

Sample size

Target

200

Accrual to date

Final

Recruitment in Australia

Recruitment state(s)

QLD

Recruitment hospital [1]

The Townsville Hospital - Douglas

Recruitment postcode(s) [1]

4814 - Douglas

Funding & Sponsors

Funding source category [1]

Government body

Name [1]

Queensland Health

Address [1]

Townsville Hospital
100 Angus Smith Drive
Douglas 4814
QLD

Country [1]

Australia

Primary sponsor type

Individual

Name

Antimony Mar

Address

Townsville Hospital
100 Angus Smith Drive
Douglas 4814
QLD

Country

Australia

Secondary sponsor category [1]

None

Name [1]

None

Address [1]

None

Country [1]

Ethics approval

Ethics application status

Approved

Ethics committee name [1]

Townsville Hospital

Ethics committee address [1]

Ethics committee country [1]

Australia

Date submitted for ethics approval [1]

26/05/2017

Approval date [1]

21/09/2017

Ethics approval number [1]

Summary

Brief summary

Chronic post surgical pain (CPSP) is a recognised and adverse outcome of many surgical procedures. It was first reported by Macrae and Davis and is defined as “pain persisting for at least two months duration following a surgical procedure”. Other causes for the pain and the possibility that the pain is from a pre-existing condition should be excluded before classifying the pain as CPSP. The prevalence of CPSP varies depending on the operation with higher rates observed after major thoracic surgery. In fact, patients undergoing thoracotomy have one of the greatest incidences of CPSP among all surgical procedures.

The etiology of chronic post-thoracotomy pain is not understood fully. It is thought to result from potential intercostal nerve damage.  As there is also a component of neuropathic pain, rather than inflammatory or nociceptive pain, central sensitisation is likely involved. Central sensitisation relies on N-methyl-D-aspartate (NMDA) receptor activation by excitatory neurotransmitters, such as glutamate and aspartate. Studies have shown that NMDA receptor antagonists, such as ketamine, can decrease CPSP.  In theory, magnesium, which is a physiologic antagonist of NMDA receptors, should prevent central sensitisation and therefore reduce the incidence of CPSP.


The aim of this study is to investigate the effects of intraoperative systemic magnesium on chronic postsurgical pain in patients undergoing thoracotomy. We propose to perform a single centre, prospective, double-blind, placebo-controlled study over the period of one year. Our hypothesis is that intra-operative systemic administration of magnesium will reduce the incidence of CPSP in patients undergoing thoracotomy. 

On the morning of surgery, block randomisation and sealed envelope method will be used to assign patients to one of the two groups: magnesium group or control group. The anaesthetist, surgeon, patient and those assessing outcomes will be blinded to the group assignment. A bolus dose of 50mg/kg of magnesium (magnesium sulfate) will be administered for 15 minutes immediately after induction and prior to skin incision, followed by infusion at 10mg/kg/hr. Patients in the control group will be administered the same volume of isotonic saline.

Patients will be assessed on postoperative day 1 and 2 by a pain team (includes anaesthetist and pain nurse). A 0-10 point numeric rating scale (NRS) will be used to measure the degree of pain intensity. Higher scores indicate a higher degree of pain. Postoperative opioid consumption (24 hours and 48 hours) will also be recorded by converting to the equivalent dose of intravenous morphine. 

Patients will be assessed at 2 and 6 months post surgery. This will be done via a telephone call from a pain nurse. Patients reporting pain will be asked to present to a chronic pain clinic for assessment by an anaesthetist. All patients will be asked to complete a Medical Outcome Study 36-Item Short Form to assess health related quality of life.

Trial website

Trial related presentations / publications

Public notes

Attachments [1]

/AnzctrAttachments/373060-SSA_17_QTHS_149_1 Approval.pdf (Supplementary information)

Attachments [2]

/AnzctrAttachments/373060-HREC17QTHS102_4 AM01.pdf (Ethics approval)

Contacts

Principal investigator

Name

Dr Christopher Butler

Address

Townsville Hospital
100 Angus Smith Drive
Douglas 4814
QLD

Country

Australia

Phone

+61744331111

Fax

Chris.Butler@health.qld.gov.au

Contact person for public queries

Name

Antimony Mar

Address

Townsville Hospital
100 Angus Smith Drive
Douglas 4814
QLD

Country

Australia

Phone

+61744331111

Fax

Antimony.Mar@health.qld.gov.au

Contact person for scientific queries

Name

Antimony Mar

Address

Townsville Hospital
100 Angus Smith Drive
Douglas 4814
QLD

Country

Australia

Phone

+61744331111

Fax

Antimony.Mar@health.qld.gov.au

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

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No additional documents have been identified.

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