Does the Speed of Sternal Retraction Affect Postoperative Pain Outcomes

Study Overview
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Brief Summary
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In North America, almost ½ million people undergo coronary artery bypass graft surgery annually and over 1/3rd develop chronic chest pain. The current study will randomize cardiac surgery patients to undergo slow sternal retraction for heart exposure (over 15 min.) versus standard-of-care (sternal opening over 30 seconds) and examine the incidence and severity of chronic post-sternotomy pain (CPSP) and quality-of life 3, 6 and 12 months post-operatively. The severity of acute post-operative pain will also be measured. Increased retraction time reduces forces required, which should translate to reduced nerve/tissue damage. If effective, this simple change in practice could be readily implemented with a major impact for patients and the health care system overall.

Detailed Description
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The overall objective of the current investigation is to determine whether increasing the time to sternal retraction to 15 minutes (from the standard  30 sec), will result in reduced acute and chronic post-sternotomy pain and an improved quality of life. The hypothesis here is that increased time to sternal retraction will result in: reduced required force, less physical trauma, less inflammation, and less nerve damage. Specifically, the hypothesis is that slow steady sternal retraction (occurring over 15 minutes) will 1) reduce the incidence of CPSP by 40% 2) reduce the severity of acute postoperative pain by at least 20-30% and 3) significantly improve quality of life 6 months postoperatively. The current investigation will be a prospective blinded, randomized, controlled trial. Following institutional ethics approval and signed consent, eligible patients scheduled for elective coronary artery bypass graft surgery will be randomly assigned (stratified by gender and surgeon to ensure equality between groups) either to the Standard group (in which sternal retraction occurs over  30s) or the Slow group in which sternal retraction occurs over 15 minutes. Patients and research personnel performing the postoperative assessments will remain blinded to group assignment until conclusion of the investigation. All other intra-operative variables will be performed as per standard practice by the cardiac surgeons at Kingston General Hospital. The extent of sternal retraction will be to the surgeon's discretion to enable appropriate exposure of the heart to allow safe conduct of the operation but it will be recorded in all cases. The primary outcome measure will be the incidence of chronic post-sternotomy chest pain 6 months following CABG with median sternotomy. However, we will also measure the incidence of CPSP at 3 and 12 months to determine the trajectory. Secondary outcomes will include: Pain intensity (numeric rating scale-NRS) of chest pain (which differs from preoperative) at rest and while coughing daily while in hospital until discharge and at 1 week postoperatively. Analgesic consumption (morphine equivalents) daily while in hospital until discharge, 1 week post-operatively and then at 3, 6, and 12 months postoperatively. Intra-operative data will include time from initiation to full retraction, latency from full retraction to sternal closure, width of sternal opening at full retraction. Pain quality, quality of life, and pain interference with daily function at 3, 6 and 12 months post-operatively. All assessments following discharge from the hospital will be via telephone calls from a research nurse blinded to randomization assignment. In-hospital assessments will also be done by a research nurse blinded to group assignment.

Official Title
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Does the Speed of Sternal Retraction During Coronary Artery Bypass Graft Surgery Affect Postoperative Pain Outcomes: A Randomized Controlled Trial

Conditions
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Chronic Pain

Intervention / Treatment
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* Procedure: slow sternal retraction


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: elective coronary artery bypass graft surgery understand written informed consent ASA I,II or III Exclusion Criteria: revision cardiac surgery current alcohol/substance abuse pre-existing chronic pain requiring chronic analgesic use rest pain in proposed surgical area preoperatively chronic steroid use inability to perform postoperative assessments

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 75 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: slow sternal retraction<br>sternal retraction (which is required for exposure of the heart during coronary artery bypass graft surgery) will be performed gradually over 15 minutes | Procedure: slow sternal retraction<br>* the sternal retraction (which always need to be performed for coronary artery bypass graft surgery) will be achieved over 15 min instead of the usual 30 sec<br>* Other names: slow retraction;|
| No Intervention: standard sternal retraction<br>sternal retraction will be performed as per standard practice (sternum opened rapidly over 30 sec.) | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Incidence of chronic post-sternotomy pain | incidence of chronic post-sternotomy pain 6 months following coronary artery bypass graft surgery | 6 months postoperatively | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Incidence of chronic post-sternotomy pain | incidence of chronic pain | 3 and 12 months postoperatively | 
| severity of chronic postoperative pain | pain on NRS scale | 3 months. 6 months, 1 year | 
| severity of acute postoperative pain at rest and with coughing | pain on NRS scale | daily while an inpatient up to 1 week postoperatively | 
| analgesic consumption |  | daily while an inpatient up to 1 week postoperatively, 1 week postoperatively, 3, 6 and 12 months postoperatively | 
| quality of life with the Modified Brief Pain Inventory (BPI) |  | 3, 6, 12 months postoperatively | 
| pain quality with the Douleur Neuropathique Questionnaire (DN4) |  | 3, 6 and 12 months postoperatively | 
| pain quality with the McGill Pain Questionnaire-short form (MPQ-SF) |  | 3, 6 and 12 months postoperatively |